From what I can judge it seems that accurate long range backcasting of the climate is no more possible than accurate long range forecasting is; precisely because of the chaos effect. Similarly, it does not seem possible to distinguish cause and effect in chaotic systems except in the most general terms. Which is not a lot of help.
But I'm not too sure if it even matters anymore whether global warming is anthropogenic or not, even if it is possible to discern the truth of the matter. From what I can gather, it is not possible to regulate chaotic systems as one would, say, an amplifier. Flips happen with no going back. If we're flipping we're flipping.
Which is not to say that we can happily continue to destroy the environment at our pleasure. It might be wise, for instance, to have lots of oceans chock full of fish as insurance against an ice age . ISTM our planning and science should therefore be directed towards surviving the flip.
Re:The Flipping Point
« Reply #31 on: 2006-07-27 13:41:48 »
On the one hand, heating has happened. This is made apparent less by the huge number of things which have changed recently (polar bear drownings, starving birds due to their prey pupating before the nesting season, mosquito migration into formerly temperate and even alpine climatic zones, thining arctic ice, shrinking Greenland and Antarctic ice masses, vanishing glaciers, 500 year droughts, heatwaves, etc) than by the clear and measurable rise in night time temperatures, which clearly validate the predictions of the scientists who early proposed CO2 warming relationships.
I suspect that there may be a number of factors which can trigger an earth-climate race condition, i.e. which provide positive feedback leading to runaway acceleration of the heating effect. If this is correct, as some climatologists are predicting, we could get a lot hotter than most projections have indicated. I am not completely persuaded that this necessarily means that a global cooling cycle will be triggered; although it is quite certain that the Europeans will get a lot cooler if the density-driven Atlantic tropical warmth conveyor shuts down. The fact that even though it has clearly weakened, hasn't resulted in this happening yet might give them some slight grounds for hope.
On the other hand, I am reasonably sure that the sun's output is scheduled to drop by perhaps 15% to 30% by the mid 2030s if the solar cycles we have identified are accurate. This correlates well with the fact that we are reaching the end of the longest period of climate stability we have been able to identify from historic data. This reduction of input energy, could well have a much stronger impact on earth than the anthropic warming cycle we are currently experiencing. So I don't know, and I don't think that anybody knows, whether we are going to end up a lot hotter or in an ice-age. Until we do know the answer, I don't think that we should be disturbing things we don't sufficiently comprehend.
An additional factor is that we have passed peak oil, and have extracted over 50% of all the fossil energy that was available on this planet. So cheap energy - and thus fertilizer - is no more. In addition, we have extracted over 80% of all known 'fossil water' from the planet, meaning that farming and food production seem to be about to suffer from massive increases in cost - or massive drops in output, or more likely both at once. This just as transport becomes problematic (especially in the USA which has largely destroyed its non-freight railways) and management of thermal excursions in houses also becomes a survivability issue. Given the removal of fuel and food from the US CPI just as fuel and food soared, this process will likely be massively progressed before people become particularly alarmed about it, and that by that point it may be too late in the day to be able to afford technological solutions.
I am reaching a point of thinking that rather than obtuseness or stupidity that this may be a keystone of the Bush administration's thinking (if we can dignify it with that name). In other words, if they can stall long enough, "Jesus" will come and "save" everyone who deserves it - while the famines and wars over diminishing resources triggered by the lack of alternatives will dispose of the rest. Just like it says in their babble.
The aforegoing makes it very difficult for a rational person to plan anything. Especially relating to where one should be thinking about moving (and if survival is considered important, and living near any major population center, moving would probably be a good thing to think about), preferably before transport becomes much more difficult (as in expensive and dangerous) than it is already. After all, if warming is coming, the equatorial South Pacific Islands as far from the shipping lanes as possible will be a bad idea (they don't have the needed height ASL), but New Zealand might be very attractive indeed - as might the still largely virginal Antarctic. If cooling is on the cards, the equatorial South Pacific Islands beckon as New Zealand is likely to get cold enough to place strict limits on crop raising. In either case, staying away from populated areas where large numbers of travellers pass and refugees might cluster, would be very sensible. Which suggests that large amounts of bullion and the willingness to move fast would be good things - perhaps the only things - other than a sizeable - and well provisioned - sailing vessel that might save a group from immediate disaster if used shortly before the bubble bursts (afterwards it would likely be too late courtesy of state or private property seizure and border controls).
<snip> The aforegoing makes it very difficult for a rational person to plan anything. Especially relating to where one should be thinking about moving (and if survival is considered important, and living near any major population center, moving would probably be a good thing to think about)</snip>
[Blunderov] Yes I agree. The prognosis looks extremely ominous.
The appended document from the Pentagon, dated 2003, makes for arresting reading. Please excuse my sad incompetence at including the pictures with the text. The full package is available for download as a Word document at http://mapcruzin.com/globalchange21/
An Abrupt Climate Change Scenario and Its Implications for United States National Security October 2003
By Peter Schwartz and Doug Randall
Imagining the Unthinkable
The purpose of this report is to imagine the unthinkable – to push the boundaries of current research on climate change so we may better understand the potential implications on United States national security.
We have interviewed leading climate change scientists, conducted additional research, and reviewed several iterations of the scenario with these experts. The scientists support this project, but caution that the scenario depicted is extreme in two fundamental ways. First, they suggest the occurrences we outline would most likely happen in a few regions, rather than on globally. Second, they say the magnitude of the event may be considerably smaller.
We have created a climate change scenario that although not the most likely, is plausible, and would challenge United States national security in ways that should be considered immediately.
Executive Summary There is substantial evidence to indicate that significant global warming will occur during the 21st century. Because changes have been gradual so far, and are projected to be similarly gradual in the future, the effects of global warming have the potential to be manageable for most nations. Recent research, however, suggests that there is a possibility that this gradual global warming could lead to a relatively abrupt slowing of the ocean’s thermohaline conveyor, which could lead to harsher winter weather conditions, sharply reduced soil moisture, and more intense winds in certain regions that currently provide a significant fraction of the world’s food production. With inadequate preparation, the result could be a significant drop in the human carrying capacity of the Earth’s environment.
The research suggests that once temperature rises above some threshold, adverse weather conditions could develop relatively abruptly, with persistent changes in the atmospheric circulation causing drops in some regions of 5-10 degrees Fahrenheit in a single decade. Paleoclimatic evidence suggests that altered climatic patterns could last for as much as a century, as they did when the ocean conveyor collapsed 8,200 years ago, or, at the extreme, could last as long as 1,000 years as they did during the Younger Dryas, which began about 12,700 years ago.
In this report, as an alternative to the scenarios of gradual climatic warming that are so common, we outline an abrupt climate change scenario patterned after the 100-year event that occurred about 8,200 years ago. This abrupt change scenario is characterized by the following conditions:
• Annual average temperatures drop by up to 5 degrees Fahrenheit over Asia and North America and 6 degrees Fahrenheit in northern Europe • Annual average temperatures increase by up to 4 degrees Fahrenheit in key areas throughout Australia, South America, and southern Africa. • Drought persists for most of the decade in critical agricultural regions and in the water resource regions for major population centers in Europe and eastern North America. • Winter storms and winds intensify, amplifying the impacts of the changes. Western Europe and the North Pacific experience enhanced winds.
The report explores how such an abrupt climate change scenario could potentially de-stabilize the geo-political environment, leading to skirmishes, battles, and even war due to resource constraints such as:
1) Food shortages due to decreases in net global agricultural production 2) Decreased availability and quality of fresh water in key regions due to shifted precipitation patters, causing more frequent floods and droughts 3) Disrupted access to energy supplies due to extensive sea ice and storminess
As global and local carrying capacities are reduced, tensions could mount around the world, leading to two fundamental strategies: defensive and offensive. Nations with the resources to do so may build virtual fortresses around their countries, preserving resources for themselves. Less fortunate nations especially those with ancient enmities with their neighbors, may initiate in struggles for access to food, clean water, or energy. Unlikely alliances could be formed as defense priorities shift and the goal is resources for survival rather than religion, ideology, or national honor.
This scenario poses new challenges for the United States, and suggests several steps to be taken:
• Improve predictive climate models to allow investigation of a wider range of scenarios and to anticipate how and where changes could occur • Assemble comprehensive predictive models of the potential impacts of abrupt climate change to improve projections of how climate could influence food, water, and energy • Create vulnerability metrics to anticipate which countries are most vulnerable to climate change and therefore, could contribute materially to an increasingly disorderly and potentially violent world. • Identify no-regrets strategies such as enhancing capabilities for water management • Rehearse adaptive responses • Explore local implications • Explore geo-engineering options that control the climate.
There are some indications today that global warming has reached the threshold where the thermohaline circulation could start to be significantly impacted. These indications include observations documenting that the North Atlantic is increasingly being freshened by melting glaciers, increased precipitation, and fresh water runoff making it substantially less salty over the past 40 years.
This report suggests that, because of the potentially dire consequences, the risk of abrupt climate change, although uncertain and quite possibly small, should be elevated beyond a scientific debate to a U.S. national security concern.
An Abrupt Climate Change Scenario and Its Implications for United States National Security October 2003
Introduction When most people think about climate change, they imagine gradual increases in temperature and only marginal changes in other climatic conditions, continuing indefinitely or even leveling off at some time in the future. The conventional wisdom is that modern civilization will either adapt to whatever weather conditions we face and that the pace of climate change will not overwhelm the adaptive capacity of society, or that our efforts such as those embodied in the Kyoto protocol will be sufficient to mitigate the impacts. The IPCC documents the threat of gradual climate change and its impact to food supplies and other resources of importance to humans will not be so severe as to create security threats. Optimists assert that the benefits from technological innovation will be able to outpace the negative effects of climate change.
Climatically, the gradual change view of the future assumes that agriculture will continue to thrive and growing seasons will lengthen. Northern Europe, Russia, and North America will prosper agriculturally while southern Europe, Africa, and Central and South America will suffer from increased dryness, heat, water shortages, and reduced production. Overall, global food production under many typical climate scenarios increases. This view of climate change may be a dangerous act of self-deception, as increasingly we are facing weather related disasters -- more hurricanes, monsoons, floods, and dry-spells – in regions around the world.
Weather-related events have an enormous impact on society, as they influence food supply, conditions in cities and communities, as well as access to clean water and energy. For example, a recent report by the Climate Action Network of Australia projects that climate change is likely to reduce rainfall in the rangelands, which could lead to a 15 per cent drop in grass productivity. This, in turn, could lead to reductions in the average weight of cattle by 12 per cent, significantly reducing beef supply. Under such conditions, dairy cows are projected to produce 30% less milk, and new pests are likely to spread in fruit-growing areas. Additionally, such conditions are projected to lead to 10% less water for drinking. Based on model projections of coming change conditions such as these could occur in several food producing regions around the world at the same time within the next 15-30years, challenging the notion that society’s ability to adapt will make climate change manageable.
With over 400 million people living in drier, subtropical, often over-populated and economically poor regions today, climate change and its follow-on effects pose a severe risk to political, economic, and social stability. In less prosperous regions, where countries lack the resources and capabilities required to adapt quickly to more severe conditions, the problem is very likely to be exacerbated. For some countries, climate change could become such a challenge that mass emigration results as the desperate peoples seek better lives in regions such as the United States that have the resources to adaptation.
Because the prevailing scenarios of gradual global warming could cause effects like the ones described above, an increasing number of business leaders, economists, policy makers, and politicians are concerned about the projections for further change and are working to limit human influences on the climate. But, these efforts may not be sufficient or be implemented soon enough.
Rather than decades or even centuries of gradual warming, recent evidence suggests the possibility that a more dire climate scenario may actually be unfolding. This is why GBN is working with OSD to develop a plausible scenario for abrupt climate change that can be used to explore implications for food supply, health and disease, commerce and trade, and their consequences for national security.
While future weather patterns and the specific details of abrupt climate change cannot be predicted accurately or with great assurance, the actual history of climate change provides some useful guides. Our goal is merely to portray a plausible scenario, similar to one which has already occurred in human experieince, for which there is reasonable evidence so that we may further explore potential implications for United States national security.
Creating the Scenario: Reviewing History
The above graphic, derived from sampling of an ice core in Greenland, shows a historical tendency for particular regions to experience periods of abrupt cooling within periods of general warming.
The Cooling Event 8,200 Years Ago The climate change scenario outlined in this report is modeled on a century-long climate event that records from an ice core in Greenland indicate occurred 8,200 years ago. Immediately following an extended period of warming, much like the phase we appear to be in today, there was a sudden cooling . Average annual temperatures in Greenland dropped by roughly 5 degrees Fahrenheit, and temperature decreases nearly this large are likely to have occurred throughout the North Atlantic region. During the 8,200 event severe winters in Europe and some other areas caused glaciers to advance, rivers to freeze, and agricultural lands to be less productive. Scientific evidence suggests that this event was associated with, and perhaps caused by, a collapse of the ocean’s conveyor following a period of gradual warming.
Longer ice core and oceanic records suggest that there may have been as many as eight rapid cooling episodes in the past 730,000 years, and sharp reductions in the ocean conveyer--a phenomenon that may well be on the horizon – are a likely suspect in causing such shifts in climate.
The Younger Dryas About 12,700 years ago, also associated with an apparent collapse of the thermohaline circulation, there was a cooling of at least 27 degrees Fahrenheit in Greenland, and substantial change throughout the North Atlantic region as well, this time lasting 1,300 years. The remarkable feature of the Younger Dryas event was that it happened in a series of decadal drops of around 5 degrees, and then the cold, dry weather persisted for over 1,000 years. While this event had an enormous effect on the ocean and land surrounding Europe (causing icebergs to be found as far south as the coast of Portugal), its impact would be more severe today – in our densely populated society. It is the more recent periods of cooling that appear to be intimately connected with changes to civilization, unrest, inhabitability of once desirable land, and even the demise of certain populations.
The Little Ice Age Beginning in the 14th century, the North Atlantic region experienced a cooling that lasted until the mid-19th century. This cooling may have been caused by a significant slowing of the ocean conveyor, although it is more generally thought that reduced solar output and/or volcanic eruptions may have prompted the oceanic changes. This period, often referred to as the Little Ice Age, which lasted from 1300 to 1850, brought severe winters, sudden climatic shifts, and profound agricultural, economic, and political impacts to Europe.
The period was marked by persistent crop failures, famine, disease, and population migration, perhaps most dramatically felt by the Norse, also known as the Vikings, who inhabited Iceland and later Greenland. Ice formations along the coast of Greenland prevented merchants from getting their boats to Greenland and fisherman from getting fish for entire winters. As a result, farmers were forced to slaughter their poorly fed livestock -- because of a lack of food both for the animals and themselves -- but without fish, vegetables, and grains, there was not enough food to feed the population.
Famine, caused in part by the more severe climatic conditions, is reported to have caused tens of thousands of deaths between 1315 and 1319 alone. The general cooling also apparently drove the Vikings out of Greenland -- and some say was a contributing cause for that society’s demise.
While climate crises like the Little Ice Age aren’t solely responsible for the death of civilizations, it’s undeniable that they have a large impact on society. It has been less than 175 years since 1 million people died due to the Irish Potato famine, which also was induced in part by climate change.
A Climate Change Scenario For the Future The past examples of abrupt climate change suggest that it is prudent to consider an abrupt climate change scenario for the future as plausible, especially because some recent scientific findings suggest that we could be on the cusp of such an event. The future scenario that we have constructed is based on the 8,200 years before present event, which was much warmer and far briefer than the Younger Dryas, but more severe than the Little Ice Age. This scenario makes plausible assumptions about which parts of the globe are likely to be colder, drier, and windier. Although intensified research could help to refine the assumptions, there is no way to confirm the assumptions on the basis of present models.
Rather than predicting how climate change will happen, our intent is to dramatize the impact climate change could have on society if we are unprepared for it. Where we describe concrete weather conditions and implications, our aim is to further the strategic conversation rather than to accurately forecast what is likely to happen with a high degree of certainty. Even the most sophisticated models cannot predict the details of how the climate change will unfold, which regions will be impacted in which ways, and how governments and society might respond. However, there appears to be general agreement in the scientific community that an extreme case like the one depicted below is not implausible. Many scientists would regard this scenario as extreme both in how soon it develops, how large, rapid and ubiquitous the climate changes are. But history tells us that sometimes the extreme cases do occur, there is evidence that it might be and it is DOD’s job to consider such scenarios.
Keep in mind that the duration of this event could be decades, centuries, or millennia and it could begin this year or many years in the future. In the climate change disruption scenario proposed here, we consider a period of gradual warming leading to 2010 and then outline the following ten years, when like in the 8,200 event, an abrupt change toward cooling in the pattern of weather conditions change is assumed to occur.
Warming Up to 2010 Following the most rapid century of warming experienced by modern civilization, the first ten years of the 21st century see an acceleration of atmospheric warming, as average temperatures worldwide rise by .5 degrees Fahrenheit per decade and by as much as 2 degrees Fahrenheit per decade in the harder hit regions. Such temperature changes would vary both by region and by season over the globe, with these finer scale variations being larger or smaller than the average change. What would be very clear is that the planet is continuing the warming trend of the late 20th century.
Most of North America, Europe, and parts of South America experience 30% more days with peak temperatures over 90 degrees Fahrenheit than they did a century ago, with far fewer days below freezing. In addition to the warming, there are erratic weather patterns: more floods, particularly in mountainous regions, and prolonged droughts in grain-producing and coastal-agricultural areas. In general, the climate shift is an economic nuisance, generally affecting local areas as storms, droughts, and hot spells impact agriculture and other climate-dependent activities. (More French doctors remain on duty in August, for example.) The weather pattern, though, is not yet severe enough or widespread enough to threaten the interconnected global society or United States national security.
Warming Feedback Loops As temperatures rise throughout the 20th century and into the early 2000s potent positive feedback loops kick-in, accelerating the warming from .2 degrees Fahrenheit, to .4 and eventually .5 degrees Fahrenheit per year in some locations. As the surface warms, the hydrologic cycle (evaporation, precipitation, and runoff) accelerates causing temperatures to rise even higher. Water vapor, the most powerful natural greenhouse gas, traps additional heat and brings average surface air temperatures up. As evaporation increases, higher surface air temperatures cause drying in forests and grasslands, where animals graze and farmers grow grain. As trees die and burn, forests absorb less carbon dioxide, again leading to higher surface air temperatures as well as fierce and uncontrollable forest fires Further, warmer temperatures melt snow cover in mountains, open fields, high-latitude tundra areas, and permafrost throughout forests in cold-weather areas. With the ground absorbing more and reflecting less of the sun’s rays, temperatures increase even higher.
By 2005 the climatic impact of the shift is felt more intensely in certain regions around the world. More severe storms and typhoons bring about higher storm surges and floods in low-lying islands such as Tarawa and Tuvalu (near New Zealand). In 2007, a particularly severe storm causes the ocean to break through levees in the Netherlands making a few key coastal cities such as The Hague unlivable. Failures of the delta island levees in the Sacramento River region in the Central Valley of California creates an inland sea and disrupts the aqueduct system transporting water from northern to southern California because salt water can no longer be kept out of the area during the dry season. Melting along the Himalayan glaciers accelerates, causing some Tibetan people to relocate. Floating ice in the northern polar seas, which had already lost 40% of its mass from 1970 to 2003, is mostly gone during summer by 2010. As glacial ice melts, sea levels rise and as wintertime sea extent decreases, ocean waves increase in intensity, damaging coastal cities. Additionally millions of people are put at risk of flooding around the globe (roughly 4 times 2003 levels), and fisheries are disrupted as water temperature changes cause fish to migrate to new locations and habitats, increasing tensions over fishing rights.
Each of these local disasters caused by severe weather impacts surrounding areas whose natural, human, and economic resources are tapped to aid in recovery. The positive feedback loops and acceleration of the warming pattern begin to trigger responses that weren’t previously imagined, as natural disasters and stormy weather occur in both developed and lesser-developed nations. Their impacts are greatest in less-resilient developing nations, which do not have the capacity built into their social, economic, and agricultural systems to absorb change.
As melting of the Greenland ice sheet exceeds the annual snowfall, and there is increasing freshwater runoff from high latitude precipitation, the freshening of waters in the North Atlantic Ocean and the seas between Greenland and Europe increases. The lower densities of these freshened waters in turn pave the way for a sharp slowing of the thermohaline circulation system.
The Period from 2010 to 2020
Thermohaline Circulation Collapse After roughly 60 years of slow freshening, the thermohaline collapse begins in 2010, disrupting the temperate climate of Europe, which is made possible by the warm flows of the Gulf Stream (the North Atlantic arm of the global thermohaline conveyor). Ocean circulation patterns change, bringing less warm water north and causing an immediate shift in the weather in Northern Europe and eastern North America. The North Atlantic Ocean continues to be affected by fresh water coming from melting glaciers, Greenland’s ice sheet, and perhaps most importantly increased rainfall and runoff. Decades of high-latitude warming cause increased precipitation and bring additional fresh water to the salty, dense water in the North, which is normally affected mainly by warmer and saltier water from the Gulf Stream. That massive current of warm water no longer reaches far into the North Atlantic. The immediate climatic effect is cooler temperatures in Europe and throughout much of the Northern Hemisphere and a dramatic drop in rainfall in many key agricultural and populated areas. However, the effects of the collapse will be felt in fits and starts, as the traditional weather patterns re-emerge only to be disrupted again—for a full decade.
The dramatic slowing of the thermohaline circulation is anticipated by some ocean researchers, but the United States is not sufficiently prepared for its effects, timing, or intensity. Computer models of the climate and ocean systems, though improved, were unable to produce sufficiently consistent and accurate information for policymakers. As weather patterns shift in the years following the collapse, it is not clear what type of weather future years will bring. While some forecasters believe the cooling and dryness is about to end, others predict a new ice age or a global drought, leaving policy makers and the public highly uncertain about the future climate and what to do, if anything. Is this merely a “blip” of little importance or a fundamental change in the Earth’s climate, requiring an urgent massive human response?
Cooler, Drier, Windier Conditions for Continental Areas of the Northern Hemisphere
The Weather Report: 2010-2020
• Drought persists for the entire decade in critical agricultural regions and in the areas around major population centers in Europe and eastern North America. • Average annual temperatures drop by up to 5 degrees Fahrenheit over Asia and North America and up to 6 degrees Fahrenheit in Europe. • Temperatures increase by up to 4 degrees Fahrenheit in key areas throughout Australia, South America, and southern Africa. • Winter storms and winds intensify, amplifying the impact of the changes. Western Europe and the North Pacific face enhanced westerly winds.
Each of the years from 2010-2020 sees average temperature drops throughout Northern Europe, leading to as much as a 6 degree Fahrenheit drop in ten years. Average annual rainfall in this region decreases by nearly 30%; and winds are up to 15% stronger on average. The climatic conditions are more severe in the continental interior regions of northern Asia and North America.
The effects of the drought are more devastating than the unpleasantness of temperature decreases in the agricultural and populated areas. With the persistent reduction of precipitation in these areas, lakes dry-up, river flow decreases, and fresh water supply is squeezed, overwhelming available conservation options and depleting fresh water reserves. The Mega-droughts begin in key regions in Southern China and Northern Europe around 2010 and last throughout the full decade. At the same time, areas that were relatively dry over the past few decades receive persistent years of torrential rainfall, flooding rivers, and regions that traditionally relied on dryland agriculture.
In the North Atlantic region and across northern Asia, cooling is most pronounced in the heart of winter -- December, January, and February -- although its effects linger through the seasons, the cooling becomes increasingly intense and less predictable. As snow accumulates in mountain regions, the cooling spreads to summertime. In addition to cooling and summertime dryness, wind pattern velocity strengthens as the atmospheric circulation becomes more zonal.
While weather patterns are disrupted during the onset of the climatic change around the globe, the effects are far more pronounced in Northern Europe for the first five years after the thermohaline circulation collapse. By the second half of this decade, the chill and harsher conditions spread deeper into Southern Europe, North America, and beyond. Northern Europe cools as a pattern of colder weather lengthens the time that sea ice is present over the northern North Atlantic Ocean, creating a further cooling influence and extending the period of wintertime surface air temperatures. Winds pick up as the atmosphere tries to deal with the stronger pole-to-equator temperature gradient. Cold air blowing across the European continent causes especially harsh conditions for agriculture. The combination of wind and dryness causes widespread dust storms and soil loss.
Signs of incremental warming appear in the southern most areas along the Atlantic Ocean, but the dryness doesn’t let up. By the end of the decade, Europe’s climate is more like Siberia’s.
An Alternative Scenario for the Southern Hemisphere There is considerable uncertainty about the climate dynamics of the Southern Hemisphere, mainly due to less paleoclimatic data being available than for the Northern Hemisphere. Weather patterns in key regions in the Southern Hemisphere could mimic those of the Northern Hemisphere, becoming colder, drier, and more severe as heat flows from the tropics to the Northern Hemisphere, trying to thermodynamically balance the climatic system. Alternatively, the cooling of the Northern Hemisphere may lead to increased warmth, precipitation, and storms in the south, as the heat normally transported away from equatorial regions by the ocean currents becomes trapped and as greenhouse gas warming continues to accelerate. Either way, it is not implausible that abrupt climate change will bring extreme weather conditions to many of the world’s key population and growing regions at the same time – stressing global food, water, and energy supply.
The Regions: 2010 to 2020
The above graphic shows a simplified view of the weather patterns portrayed in this scenario.
Europe. Hit hardest by the climatic change, average annual temperatures drop by 6 degrees Fahrenheit in under a decade, with more dramatic shifts along the Northwest coast. The climate in northwestern Europe is colder, drier, and windier, making it more like Siberia. Southern Europe experiences less of a change but still suffers from sharp intermittent cooling and rapid temperature shifts. Reduced precipitation causes soil loss to become a problem throughout Europe, contributing to food supply shortages. Europe struggles to stem emigration out of Scandinavian and northern European nations in search of warmth as well as immigration from hard-hit countries in Africa and elsewhere.
United States. Colder, windier, and drier weather makes growing seasons shorter and less productive throughout the northeastern United States, and longer and drier in the southwest. Desert areas face increasing windstorms, while agricultural areas suffer from soil loss due to higher wind speeds and reduced soil moisture. The change toward a drier climate is especially pronounced in the southern states. Coastal areas that were at risk during the warming period remain at risk, as rising ocean levels continues along the shores. The United States turns inward, committing its resources to feeding its own population, shoring-up its borders, and managing the increasing global tension.
China. China, with its high need for food supply given its vast population, is hit hard by a decreased reliability of the monsoon rains. Occasional monsoons during the summer season are welcomed for their precipitation, but have devastating effects as they flood generally denuded land. Longer, colder winters and hotter summers caused by decreased evaporative cooling because of reduced precipitation stress already tight energy and water supplies. Widespread famine causes chaos and internal struggles as a cold and hungry China peers jealously across the Russian and western borders at energy resources.
Bangladesh. Persistent typhoons and a higher sea level create storm surges that cause significant coastal erosion, making much of Bangladesh nearly uninhabitable. Further, the rising sea level contaminates fresh water supplies inland, creating a drinking water and humanitarian crisis. Massive emigration occurs, causing tension in China and India, which are struggling to manage the crisis inside their own boundaries.
East Africa. Kenya, Tanzania, and Mozambique face slightly warmer weather, but are challenged by persistent drought. Accustomed to dry conditions, these countries were the least influenced by the changing weather conditions, but their food supply is challenged as major grain producing regions suffer.
Australia. A major food exporter, Australia struggles to supply food around the globe, as its agriculture is not severely impacted by more subtle changes in its climate. But the large uncertainties about Southern Hemisphere climate change make this benign conclusion suspect.
Impact on Natural Resources The changing weather patterns and ocean temperatures affect agriculture, fish and wildlife, water and energy. Crop yields, affected by temperature and water stress as well as length of growing season fall by 10-25% and are less predictable as key regions shift from a warming to a cooling trend. As some agricultural pests die due to temperature changes, other species spread more readily due to the dryness and windiness – requiring alternative pesticides or treatment regiments. Commercial fishermen that typically have rights to fish in specific areas will be ill equipped for the massive migration of their prey.
With only five or six key grain-growing regions in the world (US, Australia, Argentina, Russia, China, and India), there is insufficient surplus in global food supplies to offset severe weather conditions in a few regions at the same time – let alone four or five. The world’s economic interdependence make the United States increasingly vulnerable to the economic disruption created by local weather shifts in key agricultural and high population areas around the world. Catastrophic shortages of water and energy supply – both which are stressed around the globe today – cannot be quickly overcome.
Impact on National Security Human civilization began with the stabilization and warming of the Earth’s climate. A colder unstable climate meant that humans could neither develop agriculture or permanent settlements. With the end of the Younger Dryas and the warming and stabilization that followed, humans could learn the rhythms of agriculture and settle in places whose climate was reliably productive. Modern civilization has never experienced weather conditions as persistently disruptive as the ones outlined in this scenario. As a result, the implications for national security outlined in this report are only hypothetical. The actual impacts would vary greatly depending on the nuances of the weather conditions, the adaptability of humanity, and decisions by policymakers.
Violence and disruption stemming from the stresses created by abrupt changes in the climate pose a different type of threat to national security than we are accustomed to today. Military confrontation may be triggered by a desperate need for natural resources such as energy, food and water rather than by conflicts over ideology, religion, or national honor. The shifting motivation for confrontation would alter which countries are most vulnerable and the existing warning signs for security threats.
There is a long-standing academic debate over the extent to which resource constraints and environmental challenges lead to inter-state conflict. While some believe they alone can lead nations to attack one another, others argue that their primary effect is to act as a trigger of conflict among countries that face pre-existing social, economic, and political tension. Regardless, it seems undeniable that severe environmental problems are likely to escalate the degree of global conflict.
Co-founder and President of the Pacific Institute for Studies in Development, Environment, and Security, Peter Gleick outlines the three most fundamental challenges abrupt climate change poses for national security:
1. Food shortages due to decreases in agricultural production 2. Decreased availability and quality of fresh water due to flooding and droughts 3. Disrupted access to strategic minerals due to ice and storms
In the event of abrupt climate change, it’s likely that food, water, and energy resource constraints will first be managed through economic, political, and diplomatic means such as treaties and trade embargoes. Over time though, conflicts over land and water use are likely to become more severe – and more violent. As states become increasingly desperate, the pressure for action will grow.
Decreasing Carrying Capacity
The graphic shows how abrupt climate change may cause human carrying capacity to fall below usage of the eco-system, suggesting insufficient resources leading to a contraction of the population through war, disease, and famine.
Today, carrying capacity, which is the ability for the Earth and its natural ecosystems including social, economic, and cultural systems to support the finite number of people on the planet, is being challenged around the world. According to the International Energy Agency, global demand for oil will grow by 66% in the next 30 years, but it’s unclear where the supply will come from. Clean water is similarly constrained in many areas around the world. With 815 million people receiving insufficient sustenance worldwide, some would say that as a globe, we’re living well above our carrying capacity, meaning there are not sufficient natural resources to sustain our behavior.
Many point to technological innovation and adaptive behavior as a means for managing the global ecosystem. Indeed it has been technological progress that has increased carrying capacity over time. Over centuries we have learned how to produce more food, energy and access more water. But will the potential of new technologies be sufficient when a crisis like the one outlined in this scenario hits?
Abrupt climate change is likely to stretch carrying capacity well beyond its already precarious limits. And there’s a natural tendency or need for carrying capacity to become realigned. As abrupt climate change lowers the world’s carrying capacity aggressive wars are likely to be fought over food, water, and energy. Deaths from war as well as starvation and disease will decrease population size, which overtime, will re-balance with carrying capacity.
When you look at carrying capacity on a regional or state level it is apparent that those nations with a high carrying capacity, such as the United States and Western Europe, are likely to adapt most effectively to abrupt changes in climate, because, relative to their population size, they have more resources to call on. This may give rise to a more severe have, have-not mentality, causing resentment toward those nations with a higher carrying capacity. It may lead to finger-pointing and blame, as the wealthier nations tend to use more energy and emit more greenhouse gasses such as CO2 into the atmosphere. Less important than the scientifically proven relationship between CO2 emissions and climate change is the perception that impacted nations have – and the actions they take.
The Link Between Carrying Capacity and Warfare Steven LeBlanc, Harvard archaeologist and author of a new book called Carrying Capacity, describes the relationship between carrying capacity and warfare. Drawing on abundant archaeological and ethnological data, LeBlanc argues that historically humans conducted organized warfare for a variety of reasons, including warfare over resources and the environment. Humans fight when they outstrip the carrying capacity of their natural environment. Every time there is a choice between starving and raiding, humans raid. From hunter/gatherers through agricultural tribes, chiefdoms, and early complex societies, 25% of a population’s adult males die when war breaks out.
Peace occurs when carrying capacity goes up, as with the invention of agriculture, newly effective bureaucracy, remote trade and technological breakthroughs. Also a large scale die-back such as from plague can make for peaceful times---Europe after its major plagues, North American natives after European diseases decimated their populations (that's the difference between the Jamestown colony failure and Plymouth Rock success). But such peaceful periods are short-lived because population quickly rises to once again push against carrying capacity, and warfare resumes. Indeed, over the millennia most societies define themselves according to their ability to conduct war, and warrior culture becomes deeply ingrained. The most combative societies are the ones that survive.
However in the last three centuries, LeBlanc points out, advanced states have steadily lowered the body count even though individual wars and genocides have grown larger in scale. Instead of slaughtering all their enemies in the traditional way, for example, states merely kill enough to get a victory and then put the survivors to work in their newly expanded economy. States also use their own bureaucracies, advanced technology, and international rules of behavior to raise carrying capacity and bear a more careful relationship to it.
All of that progressive behavior could collapse if carrying capacities everywhere were suddenly lowered drastically by abrupt climate change. Humanity would revert to its norm of constant battles for diminishing resources, which the battles themselves would further reduce even beyond the climatic effects. Once again warfare would define human life.
Conflict Scenario Due to Climate Change [Bl] (Please refer to the source for this.) The chart above outlines some potential military implications of climate change
The two most likely reactions to a sudden drop in carrying capacity due to climate change are defensive and offensive.
The United States and Australia are likely to build defensive fortresses around their countries because they have the resources and reserves to achieve self-sufficiency. With diverse growing climates, wealth, technology, and abundant resources, the United States could likely survive shortened growing cycles and harsh weather conditions without catastrophic losses. Borders will be strengthened around the country to hold back unwanted starving immigrants from the Caribbean islands (an especially severe problem), Mexico, and South America. Energy supply will be shored up through expensive (economically, politically, and morally) alternatives such as nuclear, renewables, hydrogen, and Middle Eastern contracts. Pesky skirmishes over fishing rights, agricultural support, and disaster relief will be commonplace. Tension between the U.S. and Mexico rise as the U.S. reneges on the 1944 treaty that guarantees water flow from the Colorado River. Relief workers will be commissioned to respond to flooding along the southern part of the east coast and much drier conditions inland. Yet, even in this continuous state of emergency the U.S. will be positioned well compared to others. The intractable problem facing the nation will be calming the mounting military tension around the world.
As famine, disease, and weather-related disasters strike due to the abrupt climate change, many countries’ needs will exceed their carrying capacity. This will create a sense of desperation, which is likely to lead to offensive aggression in order to reclaim balance. Imagine eastern European countries, struggling to feed their populations with a falling supply of food, water, and energy, eyeing Russia, whose population is already in decline, for access to its grain, minerals, and energy supply. Or, picture Japan, suffering from flooding along its coastal cities and contamination of its fresh water supply, eying Russia’s Sakhalin Island oil and gas reserves as an energy source to power desalination plants and energy-intensive agricultural processes. Envision Pakistan, India, and China – all armed with nuclear weapons – skirmishing at their borders over refugees, access to shared rivers, and arable land. Spanish and Portuguese fishermen might fight over fishing rights – leading to conflicts at sea. And, countries including the United States would be likely to better secure their borders. With over 200 river basins touching multiple nations, we can expect conflict over access to water for drinking, irrigation, and transportation. The Danube touches twelve nations, the Nile runs though nine, and the Amazon runs through seven.
In this scenario, we can expect alliances of convenience. The United States and Canada may become one, simplifying border controls. Or, Canada might keep its hydropower—causing energy problems in the US. North and South Korea may align to create one technically savvy and nuclear-armed entity. Europe may act as a unified block – curbing immigration problems between European nations – and allowing for protection against aggressors. Russia, with its abundant minerals, oil, and natural gas may join Europe.
In this world of warring states, nuclear arms proliferation is inevitable. As cooling drives up demand, existing hydrocarbon supplies are stretched thin. With a scarcity of energy supply – and a growing need for access -- nuclear energy will become a critical source of power, and this will accelerate nuclear proliferation as countries develop enrichment and reprocessing capabilities to ensure their national security. China, India, Pakistan, Japan, South Korea, Great Britain, France, and Germany will all have nuclear weapons capability, as will Israel, Iran, Egypt, and North Korea.
Managing the military and political tension, occasional skirmishes, and threat of war will be a challenge. Countries such as Japan, that have a great deal of social cohesion (meaning the government is able to effectively engage its population in changing behavior) are most likely to fair well. Countries whose diversity already produces conflict, such as India, South Africa and Indonesia, will have trouble maintaining order. Adaptability and access to resources will be key. Perhaps the most frustrating challenge abrupt climate change will pose is that we’ll never know how far we are into the climate change scenario and how many more years – 10, 100, 1000 --- remain before some kind of return to warmer conditions as the thermohaline circulation starts up again. When carrying capacity drops suddenly, civilization is faced with new challenges that today seem unimaginable.
Could This Really Happen? Ocean, land, and atmosphere scientists at some of the world’s most prestigious organizations have uncovered new evidence over the past decade suggesting that the plausibility of severe and rapid climate change is higher than most of the scientific community and perhaps all of the political community is prepared for. If it occurs, this phenomenon will disrupt current gradual global warming trends, adding to climate complexity and lack of predictability. And paleoclimatic evidence suggests that such an abrupt climate change could begin in the near future.
The Woods Hole Oceanographic Institute reports that seas surrounding the North Atlantic have become less salty in the past 40 years, which in turn freshens the deep ocean in the North Atlantic. This trend could pave the way for ocean conveyor collapse or slowing and abrupt climate change.
The above graphic shows early evidence that a thermohaline circulation collapse may be imminent, as the North Atlantic is increasingly being freshened by surrounding seas that have become less salty over the past 40 years.
The above two headlines appeared in Nature Magazine in 2001 and 2002, respectively. They suggest that the North Atlantic salinity level may lower, increasing the likelihood of a thermohaline circulation collapse.
With at least eight abrupt climate change events documented in the geological record, it seems that the questions to ask are: When will this happen? What will the impacts be? And, how can we best prepare for it? Rather than: Will this really happen?
Are we prepared for history to repeat itself again?
There is a debate in newspapers around the globe today on the impact of human activity on climate change. Because economic prosperity is correlated with energy use and greenhouse gas emissions, it is often argued that economic progress leads to climate change. Competing evidence suggests that climate change can occur, regardless of human activity as seen in climate events that happened prior to modern society.
It’s important to understand human impacts on the environment – both what’s done to accelerate and decelerate (or perhaps even reverse) the tendency toward climate change. Alternative fuels, greenhouse gas emission controls, and conservation efforts are worthwhile endeavors. In addition, we should prepare for the inevitable effects of abrupt climate change – which will likely come regardless of human activity.
Here are some preliminary recommendations to prepare the United States for abrupt climate change:
1) Improve predictive climate models. Further research should be conducted so more confidence can be placed in predictions about climate change. There needs to be a deeper understanding of the relationship between ocean patterns and climate change. This research should focus on historical, current, and predictive forces, and aim to further our understanding of abrupt climate change, how it may happen, and how we’ll know it’s occurring.
2) Assemble comprehensive predictive models of climate change impacts. Substantial research should be done on the potential ecological, economic, social, and political impact of abrupt climate change. Sophisticated models and scenarios should be developed to anticipate possible local conditions. A system should be created to identify how climate change may impact the global distribution of social, economic, and political power. These analyses can be used to mitigate potential sources of conflict before they happen.
3) Create vulnerability metrics. Metrics should be created to understand a country’s vulnerability to the impacts of climate change. Metrics may include climatic impact on existing agricultural, water, and mineral resources; technical capability; social cohesion and adaptability.
4) Identify no-regrets strategies. No-regrets strategies should be identified and implemented to ensure reliable access to food supply and water, and to ensure national security.
5) Rehearse adaptive responses. Adaptive response teams should be established to address and prepare for inevitable climate driven events such as massive migration, disease and epidemics, and food and water supply shortages.
6) Explore local implications. The first-order effects of climate change are local. While we can anticipate changes in pest prevalence and severity and changes in agricultural productivity, one has to look at very specific locations and conditions to know which pests are of concern, which crops and regions are vulnerable, and how severe impacts will be. Such studies should be undertaken, particularly in strategically important food producing regions.
7) Explore geo-engineering options that control the climate. Today, it is easier to warm than to cool the climate, so it might be possible to add various gases, such as hydrofluorocarbons, to the atmosphere to offset the affects of cooling. Such actions, of course, would be studied carefully, as they have the potential to exacerbate conflicts among nations.
Conclusion It is quite plausible that within a decade the evidence of an imminent abrupt climate shift may become clear and reliable. It is also possible that our models will better enable us to predict the consequences. In that event the United States will need to take urgent action to prevent and mitigate some of the most significant impacts. Diplomatic action will be needed to minimize the likelihood of conflict in the most impacted areas, especially in the Caribbean and Asia. However, large population movements in this scenario are inevitable. Learning how to manage those populations, border tensions that arise and the resulting refugees will be critical. New forms of security agreements dealing specifically with energy, food and water will also be needed. In short, while the US itself will be relatively better off and with more adaptive capacity, it will find itself in a world where Europe will be struggling internally, large number so refugees washing up on its shores and Asia in serious crisis over food and water. Disruption and conflict will be endemic features of life.
Re:The Flipping Point
« Reply #34 on: 2006-07-28 23:02:47 »
And another interesting "debunking article" for the Politburo and the vaults...
Global Warming -- Signed, Sealed and Delivered
Scientists agree: The Earth is warming, and human activities are the principal cause.
Source: LA Times Authors: Naomi Oreskes [History of Science professor at UC San Diego]. Dated: 2006-07-24
AN OP-ED article in the Wall Street Journal a month ago claimed that a published study affirming the existence of a scientific consensus on the reality of global warming had been refuted. This charge was repeated again last week, in a hearing of the House Committee on Energy and Commerce.
I am the author of that study, which appeared two years ago in the journal Science, and I'm here to tell you that the consensus stands. The argument put forward in the Wall Street Journal was based on an Internet posting; it has not appeared in a peer-reviewed journal — the normal way to challenge an academic finding. (The Wall Street Journal didn't even get my name right!)
My study demonstrated that there is no significant disagreement within the scientific community that the Earth is warming and that human activities are the principal cause.
Papers that continue to rehash arguments that have already been addressed and questions that have already been answered will, of course, be rejected by scientific journals, and this explains my findings. Not a single paper in a large sample of peer-reviewed scientific journals between 1993 and 2003 refuted the consensus position, summarized by the National Academy of Sciences, that "most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."
Since the 1950s, scientists have understood that greenhouse gases produced by burning fossil fuels could have serious effects on Earth's climate. When the 1980s proved to be the hottest decade on record, and as predictions of climate models started to come true, scientists increasingly saw global warming as cause for concern.
In 1988, the World Meteorological Assn. and the United Nations Environment Program joined forces to create the Intergovernmental Panel on Climate Change to evaluate the state of climate science as a basis for informed policy action. The panel has issued three assessments (1990, 1995, 2001), representing the combined expertise of 2,000 scientists from more than 100 countries, and a fourth report is due out shortly. Its conclusions — global warming is occurring, humans have a major role in it — have been ratified by scientists around the world in published scientific papers, in statements issued by professional scientific societies and in reports of the National Academy of Sciences, the British Royal Society and many other national and royal academies of science worldwide. Even the Bush administration accepts the fundamental findings. As President Bush's science advisor, John Marburger III, said last year in a speech: "The climate is changing; the Earth is warming."
To be sure, there are a handful of scientists, including MIT professor Richard Lindzen, the author of the Wall Street Journal editorial, who disagree with the rest of the scientific community. To a historian of science like me, this is not surprising. In any scientific community, there are always some individuals who simply refuse to accept new ideas and evidence. This is especially true when the new evidence strikes at their core beliefs and values.
Earth scientists long believed that humans were insignificant in comparison with the vastness of geological time and the power of geophysical forces. For this reason, many were reluctant to accept that humans had become a force of nature, and it took decades for the present understanding to be achieved. Those few who refuse to accept it are not ignorant, but they are stubborn. They are not unintelligent, but they are stuck on details that cloud the larger issue. Scientific communities include tortoises and hares, mavericks and mules.
A historical example will help to make the point. In the 1920s, the distinguished Cambridge geophysicist Harold Jeffreys rejected the idea of continental drift on the grounds of physical impossibility. In the 1950s, geologists and geophysicists began to accumulate overwhelming evidence of the reality of continental motion, even though the physics of it was poorly understood. By the late 1960s, the theory of plate tectonics was on the road to near-universal acceptance.
Yet Jeffreys, by then Sir Harold, stubbornly refused to accept the new evidence, repeating his old arguments about the impossibility of the thing. He was a great man, but he had become a scientific mule. For a while, journals continued to publish Jeffreys' arguments, but after a while he had nothing new to say. He died denying plate tectonics. The scientific debate was over.
So it is with climate change today. As American geologist Harry Hess said in the 1960s about plate tectonics, one can quibble about the details, but the overall picture is clear.
Yet some climate-change deniers insist that the observed changes might be natural, perhaps caused by variations in solar irradiance or other forces we don't yet understand. Perhaps there are other explanations for the receding glaciers. But "perhaps" is not evidence.
The greatest scientist of all time, Isaac Newton, [Hermit: I strongly disagree with this characterisation, unless it comes with the note that this was in fact Isaac Newton's opinion of Isaac Newton] warned against this tendency more than three centuries ago. Writing in "Principia Mathematica" in 1687, he noted that once scientists had successfully drawn conclusions by "general induction from phenomena," then those conclusions had to be held as "accurately or very nearly true notwithstanding any contrary hypothesis that may be imagined…. "
Climate-change deniers can imagine all the hypotheses they like, but it will not change the facts nor "the general induction from the phenomena."
None of this is to say that there are no uncertainties left — there are always uncertainties in any live science. Agreeing about the reality and causes of current global warming is not the same as agreeing about what will happen in the future. There is continuing debate in the scientific community over the likely rate of future change: not "whether" but "how much" and "how soon." And this is precisely why we need to act today: because the longer we wait, the worse the problem will become, and the harder it will be to solve. From http://www.uncommondescent.com/index.php/archives/1033 [Hermit] The following quote from the comments section summarizes the discussion at RealClimate fairly well (although you really should peek at his wikipedia entry supra): Quote:
If you want to read some serious discussion of Lindzen’s piece, visit Real Climate. The tongues are wagging in a more relevant venue, one hosted by working climate scientists.
Also relevant to the level of interest triggered by the piece is that Lindzen’s been riding the same horse for a very long time. There’s nothing particularly new in his piece. He specializes in trying to debunk the consensus among climatologists regarding global warming by a fairly unsubtle series of ad hominem attacks. That gets old.
He’s also a bit of a sore loser over the fact that some of his earlier work has not held up over time. As one climatologist puts it:
‘This [the IRIS paper he mentions in his WSJ editorial] is based on the idea that baroclinic neutralization maintains a particular critical temperature gradient, an idea that had a brief period of fashionability in 1978. In any case, there’s certainly been a lively debate about the paper, and if it’s widely viewed as “discredited”, then that’s the judgement of the climate dynamics community.’
"We think in generalities, we live in details"
Re:The Flipping Point
« Reply #36 on: 2006-07-30 04:18:06 »
[Eeyore] The Real Climate site is great. And as it happens I found something there especially relevant to our own discussion, included below.
It may be that I was previously too pessimistic and that perhaps something can still be done to at least ameliorate the worst effects of climate change. But still I'm not sanguine. The geological record suggests to me that we have been having it far too good for far too long.
5 Jul 2006 Runaway tipping points of no return Filed under: Climate Science Climate modelling Reporting on climate— gavin @ 12:32 pm I wonder if any else has noticed that we appear to have crossed a threshold in the usage of the phrase 'tipping point' in discussions of climate? We went from a time when it was never used, to a point (of no return?) where it is used in almost 100% of articles on the subject. Someone should come up with a name for this phenomenon....
Regardless of the recent linguistic trends, the concept has been around for a long time. The idea is that in many non-linear systems (of which the climate is certainly one), a small push away from one state only has small effects at first but at some 'tipping point' the system can flip and go rapidly into another state. This is fundamentally tied to the existence of positive feedbacks and is sometimes related to the concept of multiple 'attractors' (i.e. at any time two different 'states' could be possible and near a transition the system can flip very quickly from one to another). Another 'tipping point' in non-linear systems occurs when as some parameter varies, the current attractor changes character or disappears. However it is currently being used interchangeably a number of potentially confusing ways and so I thought I'd try and make it a little clearer.
Positive feedback A positive feedback occurs when a change in one component of the climate occurs, leading to other changes that eventually "feeds back" on the original change to amplify it. The classic ones in climate are the ice-albedo feedback (melting ice reduces the reflectivity of the surface, leading to more solar absorption, more warming and hence more melting) and the water vapour feedback (as air temperatures rise, water vapour amounts increase, and due to the greenhouse effect of the vapour, this leads to more warming), but there are lots of other examples. Of course, there are plenty of negative feedbacks as well (the increase in long wave radiation as temperatures rise or the reduction in atmospheric poleward heat flux as the equator-to-pole gradient decreases) and these (in the end) are dominant (having kept Earth's climate somewhere between boiling and freezing for about 4.5 billion years and counting). But it is the postive feedbacks that make weather chaotic and climate interesting.
People often conclude that the existence of positive feedbacks must imply 'runaway' effects i.e. the system spiralling out of control. However, while positive feedbacks are obviously necessary for such an effect, they do not by any means force that to happen. Even in simple systems, small positive feedbacks can lead to stable situations as long as the 'gain' factor is less than one (i.e. for every initial change in the quantity, the feedback change is less than the original one). A simple example leads to a geometric series for instance; i.e. if an initial change to a parameter is D, and the feedback results in an additional rD then the final change will be the sum of D+rD+r2D...etc. ). This series converges if |r|<1, and diverges ('runs away') otherwise. You can think of the Earth's climate (unlike Venus') as having an 'r' less than one, i.e. no 'runaway' effects, but plenty of positive feedbacks.
Tipping points So are there 'tipping points' in climate? One way to assess that is by looking for elements of the physical system where we think that there is a threshold behaviour. Two frequently discussed examples are the overturning circulation in the North Atlantic and the summer sea ice in the Arctic. In both of these cases, the existence of these phenomena can be disrupted in models (and there is evidence of similar behaviour in the real world) by small changes in freshwater and increasing polar amplification, respectively. At some point, both could simply cease to be viable. But we are not very confident of where these points are or how sensitive the threshold is. These are examples of 'known unknowns'.
There is also the existence of 'unknown unknowns' - tipping points that we are as yet unaware of. An example of this kind of surprise happened in relation to the Antarctic ozone hole, where unexpected chemistry on surfaces of ice particles lead to much more efficient destruction of ozone in the polar vortex than had been expected, making an existing concern into a serious problem. By their nature, we are not able to assess how important any such surprises might be, but it is impossible to rule them out entirely.
By far the most common examples of tipping points though are in relation to ecosystems. The extremely complex web of interdependencies that keep ecosystems dynamic and healthy give rise to plenty of potential thresholds and it is extremely difficult to predict consequences of external changes. The myriad influences on the health of ecosystems (habitat loss, logging, urbanization, species introduction etc. as well as climate change) means that it is most likely here that the tipping point concept will be most applicable. Examples such as a rise in minimum winter temperatures that allow a new insect species to gain a foothold in a new ecosystem (pine bark beetles in Alaska), or warming that leads to movement upward in altitude of ecosystem zones that end up reducing the area of exisiting alpine biomes. As the planet warms, it is easy to imagine an increasing number of 'tipping points' being passed, each related to some different sub-system of the climate or biosphere.
Points of no return Are 'tipping points' the same as the 'points of no return' oft used in the media? For a species that becomes extinct as a result of crossing a threshold, the answer is obviously yes. But in the physcial climate system, are there genii that can't be put back in the bottle? This is really a question of time scale. Changes to aerosol concentrations can be reversed in a few weeks after an emission change. CO2 levels however are much slower to change and are already very unlikely to revert to pre-industrial values in any scenario over the next few hundred years. In this minimal sense the climate is already past the point of no return compared to pre-industrial climate.
The 'known' physical tipping points described above have natural timescales that determine whether 'returns' are possible. The Arctic sea ice, for instance, has timescales of around 5 years to a decade, and so a collapse of summer ice cover could conceivably be reversed in a 'cooling world' after only a decade or so (interactions with the Arctic ocean stratification may make that take a little longer though). Model simulations of the thermohaline circulation indicate that for small pertubations, recovery can occur in a few decades. For larger perturbations (i.e. complete collapses) intermediate-complexity models suggest that in some regimes these changes can be quasi-permanent, although this behaviour has not yet been fully explored in current state-of-the-art GCMs. The clues from the paleo-record indicate that there is likely a bi-modal spectrum of overturning states in glacial climates, but there is no evidence of such multiple steady states in the Holocene. Thus there is no strong reason to think either of these 'tipping points' are really irreversible - though that is not to imply that the process of loss and recovery wouldn't have significant impacts.
The big 'point of no return' though is usually associated with the melting of the ice sheets - in particular, Greenland and the West Antarctic Ice Sheet (WAIS). Currently the ice sheets exist in part because they already exist i.e. the reason it snows on Greenland is in some large part because there is a large ice sheet there. Should the ice sheet start to melt in a serious way (i.e. much more significantly than current indications suggest), then lowering of the elevation of the ice sheet will induce more melting simply because of the effect of the lapse rate (air being warmer closer to sea level due to pressure effects). Thus if Greenland disappeared, it is unlikely that it would grow back even under current climate, let alone in a warmer world. So loss of either of these ice sheets would indeed be an effect with 'no return', at least on any reasonable human timescale.
10 years? Jim Hansen was widely quoted earlier this year stating that there were likely only 10 years left in which serious actions could be taken to prevent 'dangerous anthropogenic interference' on climate occuring in the future. He described this as a 'tipping point', but it should be clear that he was not using the term in exactly the same way as I defined above. He very specifically was not indicating that some irreversibly large change in climate would happen in 10 years. Instead he was pointing to the trajectory of increasing CO2 emissions that continue to add to atmospheric concentrations. Actual and projected emission levels are already at the high end of Hansen's 'alternative scenario' which was suggested as an acheivable outcome (based on significant control efforts) that kept forcings (including Co2, CH4 and black carbon) below a level that Hansen considered would be 'dangerous' (specifically a level that would avoid the melting of any significant fraction of the WAIS or Greenland ice sheet). It is the inertia of societal infrastucture, the carbon cycle and the climate that implies that at any point there is a significant warming that is already 'in the pipeline' (and thus very difficult to avoid). We have estimated this at about 0.5 C. Hansen's statement can therefore be read as a comment on a 'point of no return' of the human-climate system, rather than the climate system in a purely physical sense.
The '10 year' horizon is the point by which serious efforts will need to have started to move the trajectory of concentrations away from business-as-usual towards the alternative scenario if the ultimate warming is to stay below 'dangerous levels'. Is it realistic timescale? That is very difficult to judge. Wrapped up in the '10 year' horizon are considerations of continued emission growth, climate sensitivity, assumptions about future volcanic eruptions and solar activity etc. What is clear is that uncontrolled emissions will very soon put us in range of temperatures that have been unseen since the Eemian/Stage 5e period (about 120,000 years ago) when temperatures may have been a degree or so warmer than now but where sea level was 4 to 6m higher (see this recent discussion the possible sensitivities of the ice sheets to warming and the large uncertainties involved). In 10 years time CO2 levels will likely be greater than 400 ppm and the additional forcing combined with the inertia of the system will be make it increasingly unlikely that we will avoid a further 1 deg C or more warming. While the '10 years' shouldn't be read as an exact timetable, it is surely in the right ballpark. 30 more years of business-as-usual will make it impossible to keep temperatures from rising beyond Eemian levels (see here for some discussion of stabilisation scenarios), and decisions (on infrastructure, power stations, R&D, etc.) that are being made now will determine the emissions for decades to come.
One point or many? Much of the discussion about tipping points, like the discussion about 'dangerous interference' with climate often implicitly assumes that there is just 'a' point at which things tip and become 'dangerous'. This can lead to two seemingly opposite, and erroneous, conclusions - that nothing will happen until we reach the 'point' and conversely, that once we've reached it, there will be nothing that can be done about it. i.e. it promotes both a cavalier and fatalistic outlook. However, it seems more appropriate to view the system as having multiple tipping points and thresholds that range in importance and scale from the smallest ecosystem to the size of the planet. As the system is forced into new configurations more and more of those points are likely to be passed, but some of those points are more globally serious than others. An appreciation of that subtlety may be useful when reading some of the worst coverage on the topic.
Re:The Flipping Point
« Reply #37 on: 2006-07-31 05:47:44 »
[Blunderov] Yes I agree. The prognosis looks extremely ominous.
The appended document from the Pentagon, dated 2003, makes for arresting reading. Please excuse my sad incompetence at including the pictures with the text. The full package is available for download as a Word document at http://mapcruzin.com/globalchange21/
An Abrupt Climate Change Scenario and Its Implications for United States National Security October 2003
By Peter Schwartz and Doug Randall
[iolo] Perhaps the following will bring the above into context, and perhaps not.
This is very much in the spirit of thinking the unthinkable. The report that we put together for the Pentagon is an extreme scenario, in the sense that most climatologists would say that this is low probability, in the sense of it happening soon, and as pervasively. But it is the Pentagon's job to think about many cases, the worst-case scenario.
-- Peter Schwartz discussing the report on the BBC
As an aside, let us not forget that Schwartz is a well-known futurist (author of The Art of The Long View and The Long Boom). He's been putting out these laughable scenarios of implausibility for years, so it is a wonder why he has any credibility at all anymore.
So, this report is and is not:
It is - a highly speculative report on the potential developments in global security due to extreme climate change.
It is not - a study by either the CIA or anyone else that extreme climate change is a certainty.
What the ideological green fundamentalists want it to be - a conclusive study by the CIA that proves extreme climate change is likely and due to anthropogenic greenhouse gas emissions, and proof that “they” know The Truth™ and are covering it up.
Fortune magazine (Feb. 9) features an article by senior writer David Stipp entitled "The Pentagon's Weather Nightmare" that excerpts a report prepared by GBN for the Department of Defence. The actual report, "An Abrupt Climate Change Scenario and Its Implications for United States National Security," was written by Peter Schwartz (GBN chairman) and Doug Randall (co-head of GBN's consulting practice) and is available to the public. As is customary in military and defence-related projects, the authors describe a worst case scenario (not a prediction) for abrupt climate change. They note that "the purpose of this report is to imagine the unthinkable - to push the boundaries of current research on climate change so we may better understand the potential implications on national security." Contrary to some recent media coverage, the report was not secret, suppressed, or predictive.
To demonstrate my point about the nature of this report, a book quoting a CIA report of 1974 uses a similar scenario: Weather Conspiracy: The Coming of the New Ice Age, Impact Team Staff, Mass Market Paperback - 1st ed, April 1977, ISBN: 0345272099, 234pp, Publisher: Ballantine Books, Inc.
ps. Hermit, I will address your points, esp. Naomi Oreskes, shortly.
Re:The Flipping Point
« Reply #38 on: 2006-08-08 23:44:49 »
Around the World, Warmer Temperatures Mean More Infections
Malaria, Lyme Disease and Even Rare Shellfish Disease Spreading
Source: ABC Authors: Joy Victory Dated: 2006-04-25 [Hermit: A little late in posting this, but I think it may fill in one of the support gaps I noticed on this thread.]
At first glance, an outbreak of diarrhea among passengers on board a cruise ship in Alaskan waters in the summer of 2004 seemed to be relatively harmless.
Health officials theorized it might be the Norwalk virus, a bug that often affects people living in close quarters, such as in nursing homes, hospitals and cruise ships. While certainly annoying, Norwalk usually doesn't cause serious illness.
But then the lab reports started trickling in, and it showed that indeed a more serious problem was at hand -- many of the afflicted the passengers had eaten raw oysters raised in Alaska that were infected with a type of cholera-like bacteria, Vibrio parahaemolyticus, that normally grows on shellfish harvested in much warmer waters.
The finding not only signaled a dangerous new risk to the Alaskan seafood industry, it also highlighted how surprisingly and directly global warming can affect human health, particularly in terms of infectious diseases, experts say.
"Depending on the warming trend that unfolds in the years ahead, we have to accept that habitats will change ... new bugs can be expected to settle in. Every organism will find a niche," said epidemiology professor Colin Soskolne, of the University of Alberta in Canada. "With the tampering of the environment, we really can't predict with much certainty exactly what those changes will be."
Not Safe for Consumption
Global warming is caused by an increase in carbon dioxide and other industrial and auto emissions, which trap heat in the atmosphere and increase air and water temperatures.
While he has personally noticed Alaska's shrinking glaciers and ice floes, global warming wasn't on the mind of Dr. Joseph McLaughlin as he investigated the cruise ship disease outbreak.
He simply wanted to know why the oysters were suddenly at risk -- before this outbreak, no seafood in Alaska had ever tested positive for Vibrio because the ocean water was simply too cold for the bacteria to multiply.
But that was no longer true: An analysis showed that Alaskan water was no longer as chilly as it once was, giving Vibrio a new home up north.
"There's a sort of threshold level, above which concentrations of Vibrio in oysters become (accumulated) enough to cause illness in humans," said McLaughlin, a medical epidemiologist with the Alaska Department of Health and Social Services in Anchorage. "That temperature is about 15 degrees Celsius. What we found was that 2004 was the first summer on record during which the temperature exceeded that."
Or as McLaughlin said in a report published in the New England Journal of Medicine last October: "Rising temperatures of ocean waters seem to have contributed to one of the largest known outbreaks of V. parahaemolyticus in the United States."
The warmer water is unlikely to go away. Buoys placed by the National Oceanic and Atmospheric Association in 1976 have detected a steady annual increase of .4 degrees in the Gulf of Alaska, he said.
"We're not talking about a little bay in Prince William Sound," McLaughlin said.
Thankfully, the state health department got the word out about the outbreak and advised oyster farm owners to keep oysters deep enough where they would not be exposed to water any warmer than about 15 degrees C.
It is just one of the many ways that Alaskans have had to adapt to documented changes in the climate and environment, McLaughlin said. But it serves as a strong warning signal.
"We thought this was probably the best example of the potential of global warming impacting human health, as far as available evidence goes," McLaughlin said.
Mosquitoes and Ticks Spreading
Across the world, another microscopic bug, malaria, has caused havoc in the lowlands of Africa. It is transmitted by mosquitoes, which thrive in hot, damp areas near stagnant bodies of water.
Until recently, the mile-high city of Nairobi, Kenya, was relatively free of the disease.
But now Nairobi, despite its elevation and climate, is in the midst of a malaria outbreak.
And like the Alaskan bacterial outbreak, warmer temperatures are to blame, say scientists with the University of Michigan, the University of Hawaii, the University of Barcelona in Spain and the London School of Hygiene and Tropical Medicine.
In their report, published in last month's Proceedings of the National Academies of Science, they determined that the mosquitoes were thriving in part because it was steadily getting warmer in East Africa's higher altitudes.
This comes as no to surprise to public health researcher Dr. Paul Epstein, the associate director of the Center for Health and the Global Environment at Harvard Medical School and a medical doctor trained in tropical public health.
Along with mosquito-borne diseases like malaria, yellow fever and West Nile virus, tick-borne diseases also are an increasing problem, he said.
When winters are milder, more deer ticks reproduce year-round, transmitting infections such as Lyme disease and Rocky Mountain Spotted Fever.
According to the Centers for Disease Control and Prevention, Lyme disease cases increased from 11,700 cases in 1995 to 21,304 cases in 2005. This year could be a bad one for diseases spread by warm weather-loving insects -- 2005 was the warmest year in the last 100 years, said NASA scientists.
This not only causes more biting bugs to flourish, it also indirectly impacts humans' health in other ways. For example, when trees are weakened by drought, such as what's happening in pine forests from Alaska to Arizona, beetles eat the bark, weakening the trees even more and making them prone to wildfires, Epstein said.
And those wildfires not only release more harmful carbon dioxide and soot into the atmosphere, they trigger another major health effect of global warming: asthma.
Ragweed Loves Carbon Dioxide
For years, doctors have noted an increase in asthma and allergies.
While no one can link the increase directly to global warming, Epstein has strong evidence: When ragweed -- one of the most allergenic plants on the planet -- is grown in a carbon dioxide-rich environment, it grows 10 percent faster than normal, but produces 60 percent more pollen.
While that's good for the plants, it's bad for people. Most people are allergic to something, and often it is plant pollen. In children especially, being exposed to an allergen can trigger a dangerous asthmatic response, or inflammation of the lungs.
"As we see the seasons change and warmer weather has an earlier arrival in the spring, we're beginning to see shifts in asthma and allergies," Epstein said.
What's worse, he said, is that the tiny dust particles emitted from diesel fuel attach to plant pollens, and these diesel particles further irritate the lining of the lung.
Though there haven't been published studies showing that the rise in asthma cases is tied to global warming, Epstein said it is.
"We're seeing it and we're all experiencing it," he said.
Around the World, Warmer Temperatures Mean More Infections
Malaria, Lyme Disease and Even Rare Shellfish Disease Spreading
Source: ABC Authors: Joy Victory Dated: 2006-04-25 [Hermit: A little late in posting this, but I think it may fill in one of the support gaps I noticed on this thread.]
Global warming is caused by an increase in carbon dioxide and other industrial and auto emissions, which trap heat in the atmosphere and increase air and water temperatures.
And here it is, written as though fact when in fact it is still the central conundrum in climatology … does temperature drive CO2 or does CO2 drive temperature? A complex issue collapsed into a non-issue by the media.
But it is not just the media but also the climate models, like the IPCC’s, where the models assume what it is they are supposed to be exploring.
I saw it reported a few days ago that July, in the US (1), was the second warmest in recorded history. That, of course, feeds the global warming frenzy.
There is a problem with this statistic that will not be widely reported:
The previous record holder is in 1936. It is still the record holder. What is it about 1936 that permits it to have the hottest average July temperature for the US in spite of UHI, in spite of GHG, and in spite of any other man-made province?
How could it be true that, just 70 years ago, we experienced a higher average temperature July than any other time in recorded history? Obviously, that will take some work by Anthropogenic Global Warmer’s to explain, since they are quick to point to any local weather phenomenon as proof of hypothesis for GH gases. 2
Where were the GH gases 70 years ago? Well, obviously, it was a different cause then. And so, it may be the same cause now, only not as strong, even with the addition of GH gases. Ok, that needs clarification - the hottest July on record for all of North America happened before GH gases rose. Why? And now, with GH gases much higher, why can't we break that record? Could it possibly be because GH gases are mistakenly labelled as climate changers?
This conundrum will continue, and history will continue to bear out that our hypotheses are not yet worthy.
Two things are of keen interest here:
1. The previous record was much closer to the little ice age, which needs some kind of explanation.
2. All the GH gases of the last 70 years are not enough to overcome that record.
Well, food for thought. I am not convinced that GH gases are responsible for anything based on this kind of observation. Particularly since UHI should have pushed this year's readings artificially above those of 1936 in combination with GH gases.
Simply put - 1936, closer to an ice age, was warmer, with lower gh gases, and with lower UHI, than this year or any year since them, for North America. Where is the global warming story in that observation?
I realise that climate is composed of 30-year averages. I also recognise that observations of excessive hurricanes and other annual weather extremes are routinely blamed on GH gases.
Where are the 30-year climate averages in all these reports on global warming? Anyone that takes one year, or one season, as an example is simply forgetting to add the other 29 years to average things out. Noting that the latest shift was obviously evident in 1976, and with my understanding that the cycle is 30-40 years, it is time to be cooling back down, if not now, soon. I think most of us will see this cool-down, and endure the alarmist explanations for this most predictable event. Cooling will have to be explained in terms of human intervention. Billions will have to be spent to prevent an ice age.
The worst part is that, when earth goes into a real ice age, we will have zero possibility to prevent it. We will have to adapt, and many will die, as food production will decrease. There is little recognition that warming is a good thing. Cooling is a killer situation, and it is most definitely in our future (after all the history of our earth is one of glacial peppered with a few intervals of interglacial).
Things will reverse. When they do, every hypothesis will be forced to change. The billions wasted on global warming will have to be refocused on reality instead of hypotheses i.e. computer models. They will be focused on saving existing lives instead of hypothesised, future lives. Food shortages will occur first, and fuel will become unaffordable for many. Cooling is a very bad thing indeed. Long term cooling of the kind known just 100k years ago will kill 1/2 the population of the world, maybe more. Just imagine one mile of ice on NYC to provide some concept of the problem.
1 The same can be said of the high temperature in July in the UK which was the highest since 1911 - but what caused the 1911 high? Even Sir John Houghton recognises that 'if no climate records were being broken, that would be a record'!
2 It is usually claimed that warming between 1910 and 1945 was due to volcanic activity and that warming since 1975 is anthropogenic despite … (a) volcanic activity since 1975 and (b) the general acceptance that volcanoes put fine ash into the atmosphere and it causes warming.
At the end of this post is Appendix A: Google Alert for: "global warming" (August 7, 2006)
This sort of thing is published daily. For every time one of us sceptics says 'wait a minute, this is not proven', reports like this are published to a wide audience.
As I have thought before, and now firmly express, there is no real value in attempting to refute the AGW crowd. In essence, neither side can be proven, so each side trots out the same arguments over and over and I tire of it.
What will change the dialog? I suggest that climate change will do so, and that the climate will make a decidedly cooler change in the near future (next 10 years of so.) The climate speaks for itself, we comment about it. The climate does what it will, and we attempt to explain it. Many guesses, a bit of science and lots of prejudice. When climate changes, the prejudices will have to change (see for e.g. the global cooling scare of the 70’s). Climate change hypotheses will be revised. It will not be because I, or the sceptics as a group, 'convinced' anyone of anything; it will be because the point will be proven when the climate cools again. Even then, some will claim that the few meagre changes we have made are having an effect. Could anyone be so naive?
It should be realised that the straw house that the AGW believers have built for themselves is that climate cannot, and will not, revert back to cooling. I do not happen to tow that line. And, if I (and a whole lot of others) am right, then there is simply no valid explanation for a climate cooling in the face of the continuing emissions of GH gases. AGW’ers put us on a long term warming cycle, which cannot explain a cooling cycle in the midst of it, which we experienced only 30 years or so ago.
I can't wait. I just want the subject to change and watch all the sides change. We will be anti-human caused climate change, as usual. Only then, we will again be dealing with the impeding ice age that is predicted due to human activity.
Sigh....it is all so predictable … and possibly so to is my henceforth reluctance to participate further.
thank you - iolo
Appendix A: Google Alert for: "global warming"
Public must come together to wage war on global warming MSU State News - East Lansing,MI,USA ... It appears as though there is only one thing left to do — go to war with global warming. ... Global warming has defied us at every turn. ...
What is causing global warming? The UCLA Daily Bruin - Los Angeles,CA,USA ... No matter the cause, global warming is occurring, he said, and the polar ice caps are already melting. In the near future "the ocean could rise ... ...
INFESTED FORESTS SHOW SIGNS OF GLOBAL WARMING Kansas City Star - MO,USA ... West, in fact. It’s another effect, a number of scientists report, of climate change, also known as global warming. They point ...
Global Warming Is in Our Hands (4 Letters) New York Times - United States ... Bob Herbert says the best way to learn about global warming is to see Al Gore’s documentary, “An Inconvenient Truth.” Unfortunately, many Republicans are ... See all stories on this topic
Global warming is a myth Hagerstown Morning Herald - Hagerstown,MD,USA Tuesday - Looking back: Keedysville Historical Society works to keep history alive. Learn why its members are so involved. Wednesday ... See all stories on this topic
Global warming may be killing palms Monsters and Critics.com - Glasgow,UK ... States (UPI) -- Some palm trees along Florida`s gulf coast appear to be dying more rapidly than during previous years and that might be due to global warming. ... See all stories on this topic
Global warming could help some Michigan farmers, hurt others Centre Daily Times - Centre County,PA,USA MOUNT PLEASANT, Mich. - If global warming increases the amount of heat and the length of hot days in Michigan, the change likely would help some farmers but ... See all stories on this topic
Christians Warned Not to Jump on Global Warming Bandwagon WDC Media News - Los Angeles,CA,USA ... A conservative columnist says an attempt to align the evangelical movement with the environmental movement on the issue of global warming is "nothing new under ...
Scientists Say Melting Permafrost Could Amplify Global Warming Voice of America - USA New research shows that global warming might be worse than expected because of melting permafrost, permanently frozen soil, which can release the "greenhouse ... See all stories on this topic
Re:The Flipping Point
« Reply #40 on: 2006-08-11 12:03:54 »
I'm glad that you have stopped "debating" this issue. Possibly, at this point some progress is possible. Debate sometimes gets in the way of understanding. I think this may be one of those times.
As I have discovered and attempted to communicate, there is a huge mass of data from lots of independent disciplines which, taken as a whole, tend to establish the conclusive picture in my mind (and in the mind of every "in-discipline" scientist I have discussed this with) that things have recently become very much warmer and that CO2 levels have soared above those seen in the historic record. I think that when you focus on trying to prove this evidence wrong, you cannot address the need to establish a theory to explain the mechanism of warming (which you seem to be rejecting), and failing a coherent theory, upon the need for any such theory to produce testable predictions. The trouble is that "the experts" are saying that what you are trying to refute is the irrefutable data. The actual evidence for warming. Not their explicatory theories. I suggest that this approach is not a recipe for establishing realistic or even helpful models except as an example of "bad science".
Please notice that these are in field experts talking about observed data and its appropriate interpretation, and while it is within the bounds of probability that an "outsider" could possibly propose alternative models that address observed data; without developing at least similar expertise to the "in-discipline" experts, it is outside the boundaries of likelihood that an "outsider" will successfully "refute" the observations themselves. The best an outsider could do would be to "reject" them, but even then; without the methodological expertise possessed within the discipline, the outsider would not have the terminology to be persuasive in explaining why the rejection was seen to be needed. You appear to me to be in exactly this position. Indeed, when you speak about 1936 as having established records, despite your following this by appearing to me to agree that what was important were averages over the planet, not isolated data points for certain locations and times, you seem to me to be at odds with the historic records, as well as with the record peaks. The graph I previously provided and include below, sourced from http://www.aip.org/history/climate/20ctrend.htm, shows a post 1944 rise in warning which was addressed at some length in the text.
Attempts to reconstruct temperatures before the late nineteenth century remained controversial, but the warming since then was now as certain a fact as anything in science. A few skeptics continued to play with weather and satellite statistics, but geophysicists noted that the real buildup of heat energy was easily seen, less in the thin and variable atmosphere than in the masses of solid earth sampled by boreholes. Still more telling, layers in ocean basins — which were gradually absorbing most of the heat energy — showed a pattern of recent warming. (See above) The pattern precisely matched what computer modellers expected from greenhouse gas accumulation and nothing else.
If you compared the upward curve of 20th-century temperatures with curves showing the predictions of various computer models which simulated the effects of the sharp rise in greenhouse gases (with adjustments for volcanic eruptions and solar variations), the match was close indeed, and now soaring in an unprecedented way. Most scientists could not believe all this was mere coincidence. An International Panel on Climate Change (IPCC) that gathered the views of the world’s community of experts finally agreed, with little dissent, that it was highly likely that the strong global warming since the 1970s was in large part the work of humanity.(49)
As of this writing, the warmest year in a record going back to 1861 was still 1998. (In retrospect it was seen that in 1998 a "super El Niño" event, the strongest of the century, had pumped some heat from the Pacific Ocean into the atmosphere.) The year 2005 tied 1998. The next four warmest on record were 2002, 2003, 2001 and 2004.
Please pay attention to the last paragraph and sentence. The statements there do not agree with your (unsourced) assertions about 1936. Do you have any idea why this should be?
Re:The Flipping Point
« Reply #42 on: 2006-08-18 08:48:43 »
With a pause I return with a few comments that I trust will progress the debate.
Returning to Oreskes I offer the following:
The citing of the Oreskes paper is indeed questionable and I would advise caution when referring to it in the future. On the supposed “scientific consensus”: Dr. Naomi Oreskes, of the University of California, San Diego, did not examine a “large random sample” of scientific articles. She got her search terms wrong and thought she was looking at all the articles when in fact she was looking at only 928 out of about 12,000 articles on “climate change.” Dr. Benny Peiser, of Liverpool John Moores University in England, was unable to replicate her study. He says, “As I have stressed repeatedly, the whole data set includes only 13 abstracts (~1%) that explicitly endorse what Oreskes has called the ‘consensus view.’ In fact, the vast majority of abstracts does (sic) not mention anthropogenic climate change. Moreover — and despite attempts to deny this fact — a handful of abstracts actually questions the view that human activities are the main driving force of ‘the observed warming over the last 50 years.’” In addition, a recent survey of scientists following the same methodology as one published in 1996 found that about 30 percent of scientists disagreed to some extent or another with the contention that “climate change is mostly the result of anthropogenic causes.” Less than 10 percent “strongly agreed” with the statement. Details of both the survey and the failed attempt to replicate the Oreskes study can be found at Letter to Science Magazine I commend reading the item at this URL to everybody: one will either get a good laugh or one will blow a fuse.
[Hermit] Please pay attention to the last paragraph and sentence. The statements there do not agree with your (unsourced) assertions about 1936. Do you have any idea why this should be?
[iolo] My assertion was about the month of July 1936 being the hottest on record.
I suggest you re-read the AIP website once again before continuing with my response, and then ask yourself the very same question you have asked of me. What follows will perhaps give you an indication as to why I considered the content of AIP Website to be a load of twaddle.
Cambridge, MA - A review of more than 200 climate studies led by researchers at the Harvard-Smithsonian Center for Astrophysics has determined that the 20th century is neither the warmest century nor the century with the most extreme weather of the past 1000 years. The review also confirmed that the Medieval Warm Period of 800 to 1300 A.D. and the Little Ice Age of 1300 to 1900 A.D. were worldwide phenomena not limited to the European and North American continents. While 20th century temperatures are much higher than in the Little Ice Age period, many parts of the world show the medieval warmth to be greater than that of the 20th century.
Smithsonian astronomers Willie Soon and Sallie Baliunas, with co-authors Craig Idso and Sherwood Idso (Center for the Study of Carbon Dioxide and Global Change) and David Legates (Center for Climatic Research, University of Delaware), compiled and examined results from more than 240 research papers published by thousands of researchers over the past four decades. Their report, covering a multitude of geophysical and biological climate indicators, provides a detailed look at climate changes that occurred in different regions around the world over the last 1000 years.
"Many true research advances in reconstructing ancient climates have occurred over the past two decades," Soon says, "so we felt it was time to pull together a large sample of recent studies from the last 5-10 years and look for patterns of variability and change. In fact, clear patterns did emerge showing that regions worldwide experienced the highs of the Medieval Warm Period and lows of the Little Ice Age, and that 20th century temperatures are generally cooler than during the medieval warmth."
Soon and his colleagues concluded that the 20th century is neither the warmest century over the last 1000 years, nor is it the most extreme. Their findings about the pattern of historical climate variations will help make computer climate models simulate both natural and man-made changes more accurately, and lead to better climate forecasts especially on local and regional levels. This is especially true in simulations on timescales ranging from several decades to a century.
Historical Cold, Warm Periods Verified
Studying climate change is challenging for a number of reasons, not the least of which is the bewildering variety of climate indicators - all sensitive to different climatic variables, and each operating on slightly overlapping yet distinct scales of space and time. For example, tree ring studies can yield yearly records of temperature and precipitation trends, while glacier ice cores record those variables over longer time scales of several decades to a century.
Soon, Baliunas and colleagues analyzed numerous climate indicators including: borehole data; cultural data; glacier advances or retreats; geomorphology; isotopic analysis from lake sediments or ice cores, tree or peat celluloses (carbohydrates), corals, stalagmite or biological fossils; net ice accumulation rate, including dust or chemical counts; lake fossils and sediments; river sediments; melt layers in ice cores; phenological (recurring natural phenomena in relation to climate) and paleontological fossils; pollen; seafloor sediments; luminescent analysis; tree ring growth, including either ring width or maximum late-wood density; and shifting tree line positions plus tree stumps in lakes, marshes and streams.
"Like forensic detectives, we assembled these series of clues in order to answer a specific question about local and regional climate change: Is there evidence for notable climatic anomalies during particular time periods over the past 1000 years?" Soon says. "The cumulative evidence showed that such anomalies did exist."
The worldwide range of climate records confirmed two significant climate periods in the last thousand years, the Little Ice Age and the Medieval Warm Period. The climatic notion of a Little Ice Age interval from 1300 to1900 A.D. and a Medieval Warm Period from 800 to 1300 A.D. appears to be rather well-confirmed and wide-spread, despite some differences from one region to another as measured by other climatic variables like precipitation, drought cycles, or glacier advances and retreats.
"For a long time, researchers have possessed anecdotal evidence supporting the existence of these climate extremes," Baliunas says. "For example, the Vikings established colonies in Greenland at the beginning of the second millennium that died out several hundred years later when the climate turned colder. And in England, vineyards had flourished during the medieval warmth. Now, we have an accumulation of objective data to back up these cultural indicators."
The different indicators provided clear evidence for a warm period in the Middle Ages. Tree ring summer temperatures showed a warm interval from 950 A.D. to 1100 A.D. in the northern high latitude zones, which corresponds to the "Medieval Warm Period." Another database of tree growth from 14 different locations over 30-70 degrees north latitude showed a similar early warm period. Many parts of the world show the medieval warmth to be greater than that of the 20th century.
The study - funded by NASA, the Air Force Office of Scientific Research, the National Oceanic and Atmospheric Administration, and the American Petroleum Institute - will be published in the Energy and Environment journal. A shorter paper by Soon and Baliunas appeared in the January 31, 2003 issue of the Climate Research journal.
Headquartered in Cambridge, Massachusetts, the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists organized into six research divisions study the origin, evolution, and ultimate fate of the universe.
For more information, contact:
David Aguilar, Director of Public Affairs Harvard-Smithsonian Center for Astrophysics Phone: 617-495-7462 Fax: 617-495-7468 email@example.com
Christine Lafon Public Affairs Specialist Harvard-Smithsonian Center for Astrophysics Phone: 617-495-7463, Fax: 617-495-7016 firstname.lastname@example.org
And yet I remind the reader that Mann et al’s ‘hockey stick’ graph does a wonderful job of smoothing both of these events out of existence . . . now if only it could be replicated and the data and methods made public we might be able to progress to the falsification stage. 1
I notice that there is still a failure to provide or cite any evidence for manmade global warming, and this is not surprising because there is none, not any of any kind. And I do not think this failure is overcome by citing vested interests and political lobbying organisations such as the IPCC (of which I have close ties) that assert a belief in man-made global warming.
But perhaps I have a different concept of evidence. Perhaps. But I agree with the definitions of "evidence" provided in the 'Free Online Dictionary': viz.
1. A thing or things helpful in forming a conclusion or judgment: The broken window was evidence that a burglary had taken place. Scientists weigh the evidence for and against a hypothesis. 2. Something indicative; an outward sign: evidence of grief on a mourner's face. 3. Law The documentary or oral statements and the material objects admissible as testimony in a court of law.
According to these definitions there is no evidence for anthropogenic global warming; none, not any of any kind. Decades of research have failed to find any. Anybody who does find such evidence will surely be awarded a Nobel Prize.
There is an hypothesis that anthropogenic emissions of greenhouse gases accumulating in the air are causing AGW but there is no evidence to weigh in favour of that hypothesis; none, not any of any kind. I repeat; decades of research have failed to find any. To date nothing outside the bounds of natural climate variability has been observed. Also, no atmospheric behaviour indicative of the hypothesised AGW (i.e. an AGW 'fingerprint') has been detected: Ben Santer published a paper purporting to discern such a fingerprint but that finding was soon shown to be a function of selective use of data.
Indeed, the complete lack of evidence to weigh in favour of the AGW hypothesis is why Mann's hockey stick was so eagerly adopted by AGW-supporters. Mann's hockey stick seemed to be the first evidence of any kind to weigh in favour of the AGW hypothesis, but it is now discredited.
1 The hockey stick is the only evidence for a human signal which is why Mann promoted it so much in the IPCC Summary and continues to refuse to disclose the codes. It is also why it was so eagerly picked up by the AGW group who were desperate for evidence. Based on the Wegman report it appears possible that the peer review of the hockey stick article was done by Mann acolytes (see below). The second so-called evidence is Phil Jones 130 year 0.6°C increase in global annual temperature graph and he too refuses to disclose his method (yes, it is that graph Hermit used from the AIP Website). Finally, the only other argument for human CO2 being the cause of the recent warming is from computer models. They are also the only source of 'predictions' of future warming based on the unqualified and unjustified assumption of doubled CO2. I simply ask one to consider how such evidence and such a thesis would be viewed in a doctoral defence, let alone as the basis for global policy on energy and the environment for the next 50 years. Please see Appendix A below for more about the incestuousness and its pervasiveness.
[Hermit] As I have discovered and attempted to communicate, there is a huge mass of data from lots of independent disciplines which, taken as a whole, tend to establish the conclusive picture in my mind (and in the mind of every "in-discipline" scientist I have discussed this with) that things have recently become very much warmer and that CO2 levels have soared above those seen in the historic record. I think that when you focus on trying to prove this evidence wrong, you cannot address the need to establish a theory to explain the mechanism of warming (which you seem to be rejecting), and failing a coherent theory, upon the need for any such theory to produce testable predictions. The trouble is that "the experts" are saying that what you are trying to refute is the irrefutable data. The actual evidence for warming. Not their explicatory theories. I suggest that this approach is not a recipe for establishing realistic or even helpful models except as an example of "bad science".
[Hermit] Please notice that these are in field experts talking about observed data and its appropriate interpretation, and while it is within the bounds of probability that an "outsider" could possibly propose alternative models that address observed data; without developing at least similar expertise to the "in-discipline" experts, it is outside the boundaries of likelihood that an "outsider" will successfully "refute" the observations themselves. The best an outsider could do would be to "reject" them, but even then; without the methodological expertise possessed within the discipline, the outsider would not have the terminology to be persuasive in explaining why the rejection was seen to be needed. You appear to me to be in exactly this position. Indeed, when you speak about 1936 as having established records, despite your following this by appearing to me to agree that what was important were averages over the planet, not isolated data points for certain locations and times, you seem to me to be at odds with the historic records, as well as with the record peaks. The graph I previously provided and include below, sourced from http://www.aip.org/history/climate/20ctrend.htm, shows a post 1944 rise in warning which was addressed at some length in the text.
[Iolo] You speak of ‘combined evidence’ but merely present supposed facts that unless cause and effect are provided are merely supposed facts. In legal parlance I suppose this would be circumstantial evidence but science doesn't work with such evidence. Notice how the AGW proponents reject the ‘combined evidence’ of solar energy as a cause of the warming because there is no mechanism (cause and effect) provided. Of course, they are very good at using only those arguments that support their position, which is another practice that is unscientific. They refuse to even consider the null hypothesis, let alone that their assumptions are wrong. I would also argue that some of the items on your list are assumptions not evidence. Let me simply point to your statement that says “that things have recently become very much warmer” is not evidence of AGW - it is evidence of GW. Combining it with the other evidence doesn't alter that fact unless in the list there is proof of the cause effect relationship. This is why the hockey stick was so important to the AGW case, but also why its failure should be so devastating. I say should because they continue to obfuscate and deny and also disclose their method. The Piltdown hoax worked because the scientists involved (one in particular) so desperately wanted to find something that scientific judgment was blinded and healthy scientific scepticism was turned off.
As I understand Kuhn there are two basic scientific methods - inductive and deductive theories, which are then subjected to testing for the ability to accurately predict. With inductive you propose a theory based on assumptions and then try to find facts to disprove the theory. With deductive you have a set of facts (data) for which you try to create a hypothesis, but then test to disprove. In either case as Huxley said the great bane of science is a lovely hypothesis destroyed by an ugly fact. With AGW theory ugly facts keep appearing but for whatever reason denial is deeply entrenched.
What has happened with the AGW hypothesis is the scientific method has been effectively thwarted. As Richard Lindzen said several years ago the consensus was reached before the research had even begun. Despite their efforts evidence continues to trickle in indicating the hypothesis is wrong. As I keep stating. we have yet to see any evidence to confirm or support the hypothesis, combined or otherwise.
I have attempted to understand the logic of the AGW debate in the following manner:
My understanding is that the argument for AGW is as follows:
1. Studies indicate the earth is warming. 2. Studies indicate that GHG levels are rising. 3. Physics says that rising GHG levels are a good possible explanation for the warming. 4. The fact that the reported GHG increases are less than human emissions makes humans a good possible explanation for these increases.
Taking each in turn:
1. Studies indicate the earth is warming.
While the earth has been warming since the Little Ice Age, this is evidence of GW. It says nothing about AGW. Let me say again -- this is not evidence of AGW. This conflation of AGW and GW is one of the most prevalent misconceptions of the entire discussion of climate change.
2. Studies indicate that GHG levels are rising.
Again, this is true, but says nothing about AGW.
3. Physics says that rising GHG levels are a good possible explanation for the warming.
This is absolutely not the case, for several reasons.
The first, and most important, is that the possible change from CO2 increases is far too small to create the effects we have seen. The Idso paper (CO2-induced global warming: a skeptic’s view of potential climate change, Climate Research Vol. 10: 69–82, 1998, Sherwood B. Idso) lists ten separate natural experiments that clearly establish that the sensitivity of the temperature to a change of CO2 is on the order of 0.1°C per watt, or about 0.3 - 0.4° for a doubling. Thus, physics says that the change in CO2 over the last century is way too small to account for the observed change in temperature.
The expected warming per the Idso figures for the change in CO2 from 1900-2000 is only about 0.1°C. The temperature change is ~0.6°C, so the CO2 change can't possibly explain it. In fact, the change expected from CO2 is only half of the 2 SD uncertainty in the temperature trend for that period (+/- 0.2°C), so we can draw no conclusions at all from the temperature record.
Indeed, for the climate "models" to account for the 20th century warming, an entirely unsupported positive feedback has to be introduced into the "models". There is no evidence that such a positive feedback exists, and the whole edifice collapses without it. So the truth is, no, rising GHG levels are not a "good possible explanation" for the warming -- they require a huge imaginary feedback to come anywhere close.
In addition, the warming of the globe has occurred over the last 300 years. During the majority of this time the CO2 levels changed only slightly. Physics says that rising GHG levels had nothing to do with that part of the warming.
Finally, during the time of the initial large increase in GHGs (post WWII), the earth cooled. Physics says that if CO2 were the primary driver warming the earth, it would have warmed during this time (1940 - 1975). Since the earth did not warm during this time, physics says once again that CO2 is not a "good possible explanation" for the warming.
4. The fact that the reported GHG increases are less than human emissions makes humans a good possible explanation for these increases.
It is quite possible, even probable, that the CO2 emissions of humans have increased the atmospheric CO2 content, although the exact amount is unknown. However, since we have no evidence that changing CO2 levels have changed the temperature at all, it is not evidence for AGW.
I conclude therefore that the debate on the AGW side seems remarkably short on logic. We have Michael Mann and company using incorrect statistics and hiding their data when questioned. Phil Jones is doing the same. I note here that they are obviously not ‘convinced’ enough of the AGW hypothesis to reveal their data ... . Imaginary and illogical feedbacks are invoked to explain how CO2 will ruin the world. Steven Schneider argued passionately in the 70's that the world would freeze, and now argues passionately that it will boil. Ad hominem arguments by AGW supporters are not only common, they are defended as appropriate. Al Gore claims we can see the signs of the passage of the Clean Air Act in Antarctic ice cores with the naked eye. People are convinced that, although computers can't predict next week’s weather, they can predict next century's climate. AGW advocates compare disbelievers to Holocaust deniers. Studies show that temperature rise precedes CO2 rise in the interglacial periods, yet people believe that CO2 is driving the changes ...
Perhaps someone can explain to me the "logic" in any of that ... I see none. To me, the discussion about AGW is not a scientific discussion, it is a political discussion laced with mass hysteria, with all of the lack of logic that implies.
This discussion is occurring without context as is so often the case these days. There is a fundamental failure to distinguish between the subject, in this case climate, and the tools used to measure and analyze the subject. I have watched this development in so many areas as mathematics, statistics and then computer models were applied to research. It is particularly problematic and somwhat contradictory as manifest in the term social sciences. I won’t go into the history of this development or what stage we are at except to say that students who aren’t required to take a course in the history of science are sadly lacking in their education. Now we have people starting out in math, statistics or computer modeling turning to application of their techniques to a particular subject without basic education in those subjects. These techniques are helpful but their use without understanding of their limitations or the limitations of the material to which they are applied is extremely dangerous as Mann and others have shown. My practice is to work with specialists when I needed more than basic statistical or computational work done. However, I made sure I had enough understanding of the specialist area to know its limitations and define the problem, and also to understand the limitations of the results. There are many problems with what has evolved in climatology. Among them the fact that climate is a generalist subject in a specialist dominated world. Setting aside the early Greek work on klimat, which interestingly means angle in reference to the solar angle, most people know about meteorology but think climatology is a new study. They don’t realize that meteorology is specifically study of physics of the atmosphere, a subset of climatology. Climate study requires putting together the specialist studies including everything from cosmic radiation from deep space to geothermal heat entering the oceans (ignored in energy balance climate models). Failure to include or understand most of these specialist areas is a major reason why computer models don’t work. This development of a generalist area of study after a specialist area has dominated occurs elsewhere. For example, aerial photography began in WWI but is now a subset of remote sensing.
In my career as a climatologist I have watched the debasing of the subject until the final abuses for political purposes. I was as opposed to the hysteria about global cooling in the 1970s as I have been to the hysteria of anthropogenic warming. Some of the current warming advocates were equally vehement about cooling. I have watched what I call “peer review censorship” when articles are sent for review to the high priests of the prevailing wisdom only to be rejected as heresy and the “peer review control of funding” because the same small group generally decide who gets funded, at least here in Canada. I have watched and experienced the personal attacks and abuse or designation of scientists as skeptics and now ‘deniers’ with all the holocaust implications of that term simply because we were asking questions or trying to understand. I have watched the control of the IPCC reports from the infamous Chapter 8 event to the Hockey Stick debacle in TAR4. This control continues despite the pre-arranged ‘review’ process actually designed to combat claims of a closed process. I have watched billions of dollars wasted on government policies and schemes when more pressing and defined problems were ignored. We have the ultimate irony in Canada because Environment Canada diverted so much money to global warming propaganda, at least $4 billion by their own admission, so they had to close weather stations to get the money. Ironcally, they have almost guaranteed that an already inadequate data network is almost useless as the basis of research of climate.
Steve and Ross have done a suberb job of exposing the legerdemain of Mann, Schmidt, Weaver and the others associated with the hockey stick and its defense. However, this is only the tip of the iceberg. Beyond manipulation of data, as Warwick Hughes has long pointed out, there is the problem of the models. These ‘tools’ are the sole basis of all ‘predictions’ of future climate and they have all the problems of the hockey stick and more. I have received emails from computer model specialists identifying concerns but afraid to speak out because they are not climate experts. I hope the disclosures have just begun and are not dismissed as another witch hunt.
I think you will find your position articulated and discussed in this latter reference at much more length than I can afford, but I don't think that anything suggested there or in your submissions overturns either the conclusion that climate models are only able to simulate the temperature record of the past century when GHG forcing is included, which some insist strongly points to the importance of GHGs, as does attribution of recent climate change. (Ibid) or the IPCC's conclusion that, The prevailing scientific opinion on climate change is that "most of the warming observed over the last 50 years is attributable to human activities". Additionally, there is discussion of the consensus position (bearing in mind that the IPCC was established precisely to develop a consensus opinion) and the conclusion is as I reported earlier.
I am sure that you won't be offended when I explain that not knowing your credentials, and having discovered a number of what I took as seeming contradictions and weaknesses in your assertions, I have given them less weight than I gave to my own. Repeated articulation of your position is, I think, unlikely to progress this discussion. Too much interpretation is required and I don't have the specific expertise to analyze the assertions in the form they are presented without devoting more hours than I can afford to the subject. So I rely on what seems to me to be a very clear consensus which, in so far as I have followed up on their claims, seems to be making sense. This despite the fact that I previously held different views not dissimilar to those I understand you to be articulating, which I had to discard when they appeared to be overwhelmed by the opinions of in-field experts.
I have to add that it was you inspired my paying more attention to this field, after I had decided that global warming was very likely true but that the anthropogenic origin was less proven. You might be disconcerted to learn that the more I study, the more I am becoming persuaded of the strength of the anthropogenic global warming position.
This figure, based on Meehl et al. (2004), shows the ability with which a global climate model (the DOE PCM ) is able to reconstruct the historical temperature record and the degree to which the associated temperature changes can be decomposed into various forcing factors. The top part of the figure compares a five year average of global temperature measurements (Jones and Moberg 2001) to the Meehl et al. results incorporating the effects of five predetermined forcing factors: greenhouse gases, man-made sulfate emissions, solar variability, ozone changes (both stratospheric and tropospheric), and volcanic emissions (including natural sulfates). The time history and radiative forcing qualities for each of these factors was specified in advance and was not adjusted to specifically match the temperature record.
Also shown are grey bands indicating the 68% and 95% range for natural variability in temperature relative to the climatic expectation as determined from multiple simulations with different initial conditions. In other words, they indicate the estimated size of variations that are expected to occur due to fluctuation in weather rather than changes in climate. Ideally the model should be able to reconstruct temperature variations to within about the tolerance specified by these bands. Some of the remaining misfit may be accounted for by the ~0.05 °C uncertainty in the temperature reconstruction. However, though the model captures the gross features of twentieth century climate change, it remains likely that some of the differences between model and observation still reflect the limitations of the model and/or our understanding of the histories of the observed forcing factors.
In the lower portion of the figure are the results of additional simulations in which the model was operated with only one forcing factor used at a time. A key conclusion of the Meehl et al. (2004) work is that the model response to all factors combined is to a good approximation equal to the sum of the responses to each factor taken individually. This means it is reasonable to talk about the temperature change due to individual aspects of the evolving man-made and natural influences on climate. The zeros on both plots are set equal to 1900 temperatures, and it is apparent that most of the 0.52 °C global warming between 1900 and 1994 should be attributed to a 0.69 °C temperature forcing from greenhouse gases partially offset by a 0.27 °C cooling due to man-made sulfate emissions and with other factors contributing the balance. This contrasts with the warming from 1900 to 1940 for which the model only attributes a net increases of 0.06 °C to the combined effects of greenhouse gases and sulfate emissions. (Ibid)
Climate change is responsible for the earlier arrival of spring each year, according to a study published today.
Scientists from 17 countries reviewed 125,000 reports involving 561 species for the Europe-wide study.
They concluded that the season was beginning between six to eight days earlier than 30 years ago, when average temperatures on the continent were cooler.
Countries which experienced the greatest increases in temperatures, such as Spain, saw the earliest spring seasons.
Those behind the study, which focused on the timing of natural events such as when plants flowered and fruits formed, said it was the largest report of its kind ever conducted.
One of the report's main authors, Tim Sparks, of the Centre for Ecology and Hydrology, in Huntingdon, Cambridgeshire, said the work was "conclusive".
He told the BBC that it showed a direct link between rising annual temperatures and changes to plant and animal behaviour.
He said: "We need to look at change over very large areas and we need to examine as many species groups as possible because there has been some mild criticism that people have cherry-picked the results they presented.
"We have gone for the most complete coverage possible that we could in Europe to try and see if there was still this effect. It is very conclusive that there is."
Scientists fear that the changes to plant growing cycles could affect complex food chains in nature and harm some dependent animals.