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Hermit
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Re:The Flipping Point
« Reply #225 on: 2009-05-28 09:24:07 » |
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Greenland ice could fuel severe U.S. sea level rise
Source: Reuters
Authors: Deborah Zabarenko (Environment Correspondent), Bill Trott (Editing)
Dated: 2009-05-27
New York, Boston and other cities on North America's northeast coast could face a rise in sea level this century that would exceed forecasts for the rest of the planet if Greenland's ice sheet keeps melting as fast as it is now, researchers said on Wednesday.
Sea levels off the northeast coast of North America could rise by 12 to 20 inches more than other coastal areas if the Greenland glacier-melt continues to accelerate at its present pace, the researchers reported.
This is because the current rate of ice-melting in Greenland could send so much fresh water into the salty north Atlantic Ocean that it could change the vast ocean circulation pattern sometimes called the conveyor belt. Scientists call this pattern the meridional overturning circulation.
"If the Greenland melt continues to accelerate, we could see significant impacts this century on the northeast U.S. coast from the resulting sea level rise," said Aixie Hu, lead author of an article on the subject in the journal Geophysical Research Letters.
"Major northeastern cities are directly in the path of the greatest rise," said Hu, a scientist at the National Center for Atmospheric Research in Boulder, Colorado.
This is an even bleaker assessment than an earlier study indicated. A March article in the journal Nature Geoscience said warmer water temperatures could shift ocean currents so as to raise sea levels off the U.S. northeast coast by about 8 inches more than the average global sea level rise.
NOT LIKELY BUT POSSIBLE
However, this earlier research did not include the impact of melting Greenland ice, which would speed changes in ocean circulation and send 4 to 12 more inches of water toward northeastern North America, on top of the average global sea level rise.
That could put residents of New York, Boston and Halifax, Nova Scotia, at risk since these cities and others lie close to sea level now, Hu said in answer to e-mailed questions.
Not only would coastal residents be at direct risk from flooding but drainage systems would suffer as salty ocean water would move back into river deltas, changing the biological environment, Hu wrote in an e-mail. [ Hermit : Not discussed is the high probability that increasing sea levels and decreasing aquifer levels will accelerate the salination of ground water and commensurate damage to irrigated soil. ]
"In a flooding zone, because the higher sea level may impede the function of the drainage system, the future flood may become more severe," he wrote. If cities are prone to subsidence -- where the ground sinks -- higher sea levels would also make that problem worse, according to Hu.
The ice that covers much of Greenland is melting faster now due to global climate change, raising world sea levels. But sea level does not rise evenly around the globe. Sea level in the North Atlantic is now 28 inches lower than in the North Pacific, because the Atlantic has a dense, compact layer of deep, cold water that the Pacific lacks.
Greenland's ice-melt rate has increased by 7 percent a year since 1996 but Hu said it is unlikely to continue. Still, he and his co-authors ran computer simulations that included this fast-paced melting, along with more moderate scenarios with ice-melt increasing by 3 percent or 1 percent annually.
Hu said it was hard to say whether the 7 percent annual increase could go on for the next 50 years but said it was possible since the current rate of increase in climate-warming carbon dioxide is higher than the high end of projections by the U.N. Intergovernmental Panel on Climate Change.
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Re:The Flipping Point
« Reply #226 on: 2009-06-18 12:11:31 » |
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White House Climate Change Report Issues Dire Warning On Worsening Situation
Source: HuffingtonPost.com
Authors: Seth Borenstein (Reporter), Dina Cappiello (Associated Press Writer)
Dated: 2009-06-16
Related: U.S. Global Change Research Program
Rising sea levels, sweltering temperatures, deeper droughts, and heavier downpours _ global warming's serious effects are already here and getting worse, the Obama administration warned on Tuesday in the grimmest, most urgent language on climate change ever to come out of any White House.
But amid the warnings, scientists and government officials seemed to go out of their way to soften the message. It is still not too late to prevent some of the worst consequences, they said, by acting aggressively to reduce world emissions of heat-trapping gases, primarily carbon dioxide from the burning of fossil fuels.
The new report differs from a similar draft issued with little fanfare or context by George W. Bush's administration last year. It is paradoxically more dire about what's happening and more optimistic about what can be done.
The Obama administration is backing a bill in Congress that would limit heat-trapping pollution from power plants, refineries and factories. A key player on a climate bill in the Senate, California Democrat Barbara Boxer, said the report adds "urgency to the growing momentum in Congress" for passing a law.
"It's not too late to act," said Jane Lubchenco, one of several agency officials at a White House briefing. "Decisions made now will determine whether we get big changes or small ones." But what has happened already is not good, she said: "It's happening in our own backyards and it affects the kind of things people care about."
Lubchenco, a marine biologist, heads the National Oceanic and Atmospheric Administration.
In one of its key findings, the report warned: "Thresholds will be crossed, leading to large changes in climate and ecosystems." The survival of some species could be affected, it said.
The document, a climate status report required periodically by Congress, was a collaboration by about three dozen academic, government and institute scientists. It contains no new research, but it paints a fuller and darker picture of global warming in the United States than previous studies.
Bush was ultimately forced by a lawsuit to issue a draft report last year, and that document was the basis for this one. Obama science adviser John Holdren called the report nonpartisan, started by a Republican administration and finished by a Democratic one.
"The observed climate changes that we report are not opinions to be debated. They are facts to be dealt with," said one of the report's chief authors, Jerry Melillo of Marine Biological Lab in Woods Hole, Mass. "We can act now to avoid the worst impacts."
Among the things Melillo said he would like to avoid are more flooding disasters in New Orleans and an upheaval of the world's food supply.
The scientists softened the report from an earlier draft that said "tipping points have already been reached and have led to large changes." Melillo said that is because some of the changes seen so far are still reversible.
Even so, Tom Karl of the National Climatic Data Center said that at least one tipping point _ irreversible sea level rise _ has been passed.
A point of emphasis of the report, which is just under 200 pages, is what has already happened in the United States. That includes rapidly retreating glaciers in the American West and Alaska, altered stream flows, trouble with the water supply, health problems, changes in agriculture, and energy and transportation worries.
"There are in some cases already serious consequences," report co-author Anthony Janetos of the University of Maryland told The Associated Press. "This is not a theoretical thing that will happen 50 years from now. Things are happening now."
For example, winters in parts of the Midwest have warmed by 7 degrees in just 30 years and the frost-free period has grown a week, the report said.
Shorter winters have some benefits, such as longer growing seasons, but those are changes that require adjustments just the same, the authors note.
The "major disruptions" already taking place will only increase as warming continues, the authors wrote. The world's average temperature may rise by as much as 11.5 degrees by the end of the century, the report said. And the U.S. average temperature could go even higher than that, Karl said.
Environmental groups praised the report as a call for action, with the Union of Concerned Scientists calling it what "America needs to effectively respond to climate change."
Scott Segal, a Washington lobbyist for the coal industry, was more cautious: "Fast action without sufficient planning is a route to potential economic catastrophe with little environmental gain." [ Hermit : Almost as unexpected as a tobacco lobbyist arguing that smoking might not cure cancer. ]
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Re:The Flipping Point
« Reply #227 on: 2009-07-01 12:37:15 » |
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source: Telegraph UK
Polar bear expert barred by global warmists
Over the coming days a curiously revealing event will be taking place in Copenhagen. Top of the agenda at a meeting of the Polar Bear Specialist Group (set up under the International Union for the Conservation of Nature/Species Survival Commission) will be the need to produce a suitably scary report on how polar bears are being threatened with extinction by man-made global warming.
This is one of a steady drizzle of events planned to stoke up alarm in the run-up to the UN's major conference on climate change in Copenhagen next December. But one of the world's leading experts on polar bears has been told to stay away from this week's meeting, specifically because his views on global warming do not accord with those of the rest of the group.
Dr Mitchell Taylor has been researching the status and management of polar bears in Canada and around the Arctic Circle for 30 years, as both an academic and a government employee. More than once since 2006 he has made headlines by insisting that polar bear numbers, far from decreasing, are much higher than they were 30 years ago. Of the 19 different bear populations, almost all are increasing or at optimum levels, only two have for local reasons modestly declined.
Dr Taylor agrees that the Arctic has been warming over the last 30 years. But he ascribes this not to rising levels of CO2 – as is dictated by the computer models of the UN's Intergovernmental Panel on Climate Change and believed by his PBSG colleagues – but to currents bringing warm water into the Arctic from the Pacific and the effect of winds blowing in from the Bering Sea.
He has also observed, however, how the melting of Arctic ice, supposedly threatening the survival of the bears, has rocketed to the top of the warmists' agenda as their most iconic single cause. The famous photograph of two bears standing forlornly on a melting iceberg was produced thousands of times by Al Gore, the WWF and others as an emblem of how the bears faced extinction – until last year the photographer, Amanda Byrd, revealed that the bears, just off the Alaska coast, were in no danger. Her picture had nothing to do with global warming and was only taken because the wind-sculpted ice they were standing on made such a striking image.
Dr Taylor had obtained funding to attend this week's meeting of the PBSG, but this was voted down by its members because of his views on global warming. The chairman, Dr Andy Derocher, a former university pupil of Dr Taylor's, frankly explained in an email (which I was not sent by Dr Taylor) that his rejection had nothing to do with his undoubted expertise on polar bears: "it was the position you've taken on global warming that brought opposition".
Dr Taylor was told that his views running "counter to human-induced climate change are extremely unhelpful". His signing of the Manhattan Declaration – a statement by 500 scientists that the causes of climate change are not CO2 but natural, such as changes in the radiation of the sun and ocean currents – was "inconsistent with the position taken by the PBSG".
So, as the great Copenhagen bandwagon rolls on, stand by this week for reports along the lines of "scientists say polar bears are threatened with extinction by vanishing Arctic ice". But also check out Anthony Watt's Watts Up With That website for the latest news of what is actually happening in the Arctic. The average temperature at midsummer is still below zero, the latest date that this has happened in 50 years of record-keeping. After last year's recovery from its September 2007 low, this year's ice melt is likely to be substantially less than for some time. The bears are doing fine.
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Re:The Flipping Point
« Reply #228 on: 2009-07-01 14:20:46 » |
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I think that the Telegraph has written a beautifully politicized article perfectly matching, to an almost incredible degree, the preconceptions of its readership, and in the process included so many bad assumptions that it falls in the category of "So bad it isn't even wrong." Reading the lengthy article on the Polar Bear at wikipedia should put you on track to correct it.
Kindest Regards
Hermit & Co
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the.bricoleur
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Re:The Flipping Point
« Reply #229 on: 2009-07-02 08:10:05 » |
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Indeed. From the Wiki article:
Quote:Controversy over species protection
Warnings about the future of the polar bear are often contrasted with the fact that worldwide population estimates have increased over the past 50 years and are relatively stable today.[103][118] |
And:
Quote:| The global polar bear population, estimated to be 22,000-25,000 bears, is relatively stable.[103] However, in 2006, the World Conservation Union (IUCN) upgraded the polar bear from a species of Least Concern to a vulnerable species.[104] It cited a "suspected population reduction of >30% within three generations (45 years)", due primarily to global warming.[1] Other risks to the polar bear include pollution in the form of toxic contaminants, conflicts with shipping, stresses from recreational polar-bear watching, and oil and gas exploration and development.[1] The IUCN also cited a "potential risk of over-harvest" through legal and illegal hunting.[1] |
I think stating it to be "primarily" due to global warming is disingenuous, as a warmer climate is the only factor listed that the polar bears have previously encountered and survived.
-iolo.
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Re:The Flipping Point
« Reply #230 on: 2009-07-02 09:20:32 » |
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[Iolo] I think stating it to be "primarily" due to global warming is disingenuous, as a warmer climate is the only factor listed that the polar bears have previously encountered and survived.
[Hermit] When?
I think you are making unwarranted assumptions.
Don't forget that all bears separated from seals relatively recently, and genetic evidence shows that Ursus maritimus, the Polar Bear, is a very recent adaptation from Ursus arctos, the Brown Bear, which established an isolated breeding colony, probably after being separated by glaciers sometime after 125 kYBP (after the end of the last Interglaciation at about 140 kYBP) and sub-speciated between then and 100 kYBP which is the currently accepted dating for the oldest fossil evidence for Polar bears. So we are quite sure that Polar bears did not exist the last time that the Arctic was significantly warmer than present, in other words they are clearly a post Interglacial adaptation.
Even if we ignore all the evidence and pretend that Polar bears did live through the last Interglaciation, or assert that the Arctic has warmed substantially since then, we still couldn't predict ocean temperatures or how that affected the ice shelf, as the models are as yet far from conclusive. This means that predicting how this might affect Polar bears is stepping out onto a very tenuous path over thin ice indeed.
If, for the sake of the discussion, we assume that Arctic Bears or their close predecessors were around at a time when the ice shelf failed, consider that evolution is not conservative and their total dependence on their modern high energy, purely carnivorous diet of fat acquired only on that shelf may be a relatively recent adaptation and yet it could still be irreversible. In this regard, the changes in population quality, particularly breeding success, in the last 40 years of mild change, don't give me a good feeling about their prognosis.
Finally, I think it is very safe to say that, as the apex predator, Polar bears are vulnerable to any change in any of the subordinate populations, and that even aside from the deleterious impact a relatively rapid reduction in ice shelf or snow pack availability might have on their behaviour, warmer waters will reduce oxygen levels and so reduce algae, plankton, krill, fish, seal, walrus and prey whale populations with likely significant impact on Polar bears in all their eco-niches.
Kind Regards
Hermit & Co
[ Hermit : Here, even if like its subjects, it is a little long in the tooth, is a much better article. And the cute multiply referenced photograph. Enjoy.
Living on thin ice
Source: The Observer
Authors: Simon Garfield
Dated: 2007-03-04
Refer Also: Watch a slideshow featuring polar bears here (Flash)
Not so long ago polar bears were a symbol of cold, but these days they are a symbol of warmth. In the past few weeks it has become difficult to open a newspaper or web page without seeing photographs of the beautiful yellowy-white animals leaping, or lying on sea ice in the Arctic, the newly helpless emblem of climate change. The traditional threats to the polar bear - hunting, toxic waste, offshore drilling - have been overshadowed by a new one: the ice around them is melting, and we are to blame.
This new threat is not new, of course - about as new as deforestation. But two things have put the polar bears on top of the vanishing ice, where they pose unwittingly as the latest poster animals in a distinguished and photogenic parade of endangered pandas, gorillas, dolphins and whales. At the end of December, the US Secretary of the Interior revealed the US Fish and Wildlife Service was considering adding the polar bear to its list of threatened species. A three-month consultation process began in January, and the world's Arctic specialists have been making appointments to deliver their expertise. This is a more significant addition to the at-risk list than a rare gazelle or panther: it is an admission, after years of denial, of the existence of global warming. The Bush administration could no longer disavow the effects of climate change if one of its departments had acknowledged such visible and dramatic effects. The polar bear had done what environmentalists could not, and opened a window on a global crisis. Three lawsuits against the White House - from Greenpeace, the Center for Biological Diversity and the Natural Resources Defense Council - were settled at a stroke.
Then, at the beginning of February, the Intergovernmental Panel on Climate Change (IPCC) delivered its damning verdict on rising temperatures and disappearing sea ice, and polar bears had even more reason to feel loved. Six hundred scientists attempted to dismiss all lingering cynicism about global warming, and to pin the blame on its human perpetrators. The reality is now stark and quantifiable, they stated, and in some areas the devastation is irreversible: we are already too late, for example, to avert the effects of the recent rises in sea levels. This news is particularly bad for polar bears, for the earlier melting of spring ice and the later formation of autumn ice has an immediate impact on their ability to feed. In some areas there is evidence that sea ice breaks up three weeks earlier than it did 30 years ago.
Which seems to be good news for polar bear photographers. There is no such thing as an ugly polar bear, and even the less handsome ones appear to have learnt to conceal their claws as they leap the ice floes. Like panting labradors, they always appear to be smiling (no such fillip for the equally threatened but unglamorous walrus).
One photograph in particular has captured the imagination. In a neat piece of marketing, the Canadian Ice Service made available a stunning image to coincide with the IPCC report. Two bears, probably a mother and her cub, are pictured on a spectacular ice block off northern Alaska that might have been modelled by Henry Moore. They appear to be howling against injustice. The drama is clear: this is truly the tip of an iceberg, the bears are desperately stranded as the water swells around them. The first thought among viewers is surely one of pity and concern, but this is to misjudge the situation: polar bears are reasonable swimmers, and certainly climbed upon such sculptures centuries before we climbed into our 4x4s.
'Initially I thought the picture was a Photoshop fake,' Dr Ian Stirling, senior research scientist with the Canadian Wildlife Service, emails from his home in Edmonton. 'But I have since checked and it is authentic. There is no doubt the photo is used because of its dramatic effect, and it is true it does not represent the kind of sea ice bears normally live on and depend upon for hunting seals.'
The photograph was taken in 2004. Naysaying bloggers have used the fact the picture has been romanticised to discredit the claim of bears at risk, and in some cases the very existence of global warming. Several sites link to the original text that accompanied the photograph when it was first used three years ago, in an online journal of the Beaufort Gyre Exploration Project, in which the ice block is described as 'extraordinary'. The bears were seen during a late-summer arctic drilling mission that found the ice much thicker than expected.
Elsewhere, images of the polar bear are used to further other ends. The World Wildlife Fund features four of them, sketched in Biro, in its latest magazine campaign to 'Change the world with a pen', an attempt to encourage corporate responsibility: 'Climate change is no longer a debate,' the advertisement says, 'it's a business challenge.'
'The fate of the polar bear has been on our minds for several years,' says Stefan Norris, head of conservation for the WWF International Arctic Programme. 'The polar bear is at the very top of the food chain, and is easy to sell, and is an iconic species - but they are just an indication of what's happening to the entire Arctic ecosystem.'
Easy to sell, but hard to save. Despite their uncertain fate, you wouldn't mind having their PR account. They look sweet, embraceable even. Those who have run from them on land, or witnessed a savage, ripping kill on an ice floe will have a different perspective, but the bears do not yet seem to be aware they are a business challenge, or even that another TV crew is at this very moment packing for a trip to Churchill, Manitoba, for a closer glimpse of the imperilled bears, and an examination of their myths. No, polar bears are not left-handed. They do not kill seals with blocks of ice, although they do occasionally pound the ice in frustration when a seal gets away. And they do not cover their black noses for camouflage when stalking their next meal.
The polar bear has traditionally been an adaptable creature. But, though it may receive a little sustenance from birds' eggs and from scavenging in rubbish bins, it cannot survive without large supplies of seal meat and blubber, and for its kill it must be on or near sea ice. And the problem is broader still. Polar bears may be feeding on fewer seals not just because of melting sea ice; the seals may be declining because they aren't finding enough fish, and the fish aren't finding sufficient krill, and the krill aren't finding the algae.
'Every time we look at this, the urgency becomes greater,' Norris says. 'The scientific thinking in 2004 was that there was a significant chance that at the end of the 21st century there would be no sea ice at all at the North Pole during the summer. But at the end of 2006 the US Geological Service came out with a report that this is likely to happen by the middle of this century, in the lifetime of our kids.'
How did we get here? There is no agreed date which we can pinpoint as the beginning of our concern for Ursus maritimus. A more civilised approach to their fate began, perhaps, in 1985, when the polar bears disappeared from London Zoo at the temporary closure of the Mappin Terraces. Animal husbandry matured: Regents Park was no longer considered the ideal habitat for the King of the Arctic. The last polar bear in Britain is a female called Mercedes at Edinburgh Zoo, who looks distinctly forlorn on her website photo.
But we could just as reasonably choose 1993, the year Coca-Cola adopted the animal to spearhead its new global marketing campaign. The Cola Bear reinforced the notion that Coke was best served ice-cold, and it was a drink that spread the love: the bears, who made deep and reassuring guttural noises and never had seal blood on their fur, were represented in family groups playing with penguins and admiring the Aurora Borealis. There was no cuter or more deceptively cuddly anthropomorphism on the tundra - the little ones even wore red scarves - and merchandise followed; keyrings, soft toys, pencil toppers, now quite big on eBay. The only downside for the polar bears was they didn't own their image rights.
That was also the year when Dr Ian Stirling and Dr Andrew Derocher, both of the International Union for Conservation of Nature's Polar Bear Specialist Group (IUCN PBSG), wrote their first scientific paper on what they perceived as a deterioration in the condition of polar bears in western Hudson Bay, Canada; they also noted unfamiliar patterns in the break-up of ice. Another paper appeared six years later with stronger evidence, and since then similar patterns have been reported in five of the 19 polar bear sub-populations in the Arctic. More young cubs are found dead each year; adults have lost weight, from an average of 650lb in 1980 to 507lb in 2004; there have been instances of cannibalism; and in western Hudson Bay the polar bear population decreased from 1,200 in the mid-Nineties to less than 1,000 in 2004.
There are thought to be between 20,000 and 25,000 polar bears in the world, and all but one member of the PBSG believe global warming poses a critical threat to their long-term survival. The exception, quoted by contrarian writers, is Dr Mitchell Taylor from the Government of Nunavut, who remains sceptical about the climate modelling projections and their impact. 'I'm not sure I understand his logic,' Stirling says. 'However, at the last meeting of the IUCN PBSG in Seattle in June 2005 the group [including Dr Taylor] unanimously agreed to classify the polar bear as vulnerable.'
But as numbers decline, polar tourism flourishes. Companies promise a trip like no other, with buggy tours lasting two days and one evening, 'long enough,' one brochure states, 'for nature enthusiasts to keep their excitement, but not too long to the point of monotony.' The same brochure also advertises the 'Ultimate Churchill', which offers an optional helicopter journey to the female bears' denning area 'where we can have the chance to crawl inside an unoccupied polar bear den'.
The path to preservation has been a slippery one. There have been laws prohibiting excessive hunting since the Seventies, and concern about oil drilling began a decade later, but the case for climate change demanded sterner proof. In 2001, the WWF issued a report called Polar Bears at Risk, but it was speculative. According to Stefan Norris, 'We had a little trouble getting the scientists to say, "Yes, there is a one-to-one link here" because there hadn't been long enough statistical studies to link everything together. But we're now seeing direct scientific linkages in Canada, Alaska, Norway and Russia.'
Norris says the WWF has come under a lot of pressure to predict when polar bears will become extinct, but no one is prepared to be so precise, or so doom-laden. He is increasingly optimistic that an immediate cut in greenhouse gas emissions 'may yet turn the ship around'.
Others are less certain. Peter Wadhams, professor of ocean physics at Cambridge, has made frequent observations of Arctic sea ice from submarines, recording more than a 40 per cent loss in ice thickness in the past 25 years. He is not surprised at predictions that the Arctic summer ice will disappear much earlier than previously envisaged - 'perhaps before 2040'. Wadhams says he is about to leave Britain due to inadequate funding for his research, despite its influence on government reports. He is one of those scientists who has no difficulty making a direct link between climate change and the fate of the polar bear. 'If the pack ice has retreated far from the coast, the bear will start swimming, thinking there is only a small shore lead, as has usually happened in the past. If the distance to the ice is too great, he may tire and drown. This has been observed in bears denning in north Alaska then trying to get out on to the Beaufort Sea pack ice.'
After years of hesitancy, there is now a sense of urgency. Tomorrow night in Washington the US Fish and Wildlife Service will hold the second of its public hearings on whether the polar bear should be officially regarded as a threatened species. The third and final meeting takes place in Alaska two days later. But it may be too late to be squabbling over semantics. To some extent the fate of the polar bear is already fixed: unless it is able to adapt to spending far greater periods of the year on land, it may not recover from our devastating impact on its Arctic environment.
But not all polar bears are in the Arctic. This month the Horniman Museum in London has a timely display of 32 photographs of polar bears, and they make sober viewing. They are all stuffed, and their habitat is wooden packing crates and storage units: this is a collection of every taxidermists' polar bear in Britain. A chilly vision of the past and, maybe, the future too.
Polar bears off northern Alaska. Photo: Dan Crosbie/Canadian Ice Service/PA Wire
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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the.bricoleur
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Re:The Flipping Point
« Reply #231 on: 2009-07-06 14:02:30 » |
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Quote from: Hermit on 2009-07-02 09:20:32 [Iolo] I think stating it to be "primarily" due to global warming is disingenuous, as a warmer climate is the only factor listed that the polar bears have previously encountered and survived.
[Hermit] When? |
1880-1940, and this is only within our short instrumental record. Taken from the Jones, et al dataset (HadCRUT3 and CRUTEM3), which also demonstrates that the temperature rise then was steeper, larger and longer than the current rise.
Question is, if the polar bears survived then why will they not survive now, what is different?
-iolo
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Hermit
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Re:The Flipping Point
« Reply #232 on: 2009-07-06 15:21:11 » |
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Not the data set I would choose, but glimpsing at it, it does not appear to support your assertions.
http://www.cru.uea.ac.uk/cru/data/temperature/
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Hermit
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Re:The Flipping Point
« Reply #233 on: 2009-07-13 07:53:07 » |
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For those who asked (and even more, for those who didn't), the reason I placed, "so bad it isn't even wrong" in quote marks is because it is a quote. Duh. One of my favourites that does not get enough exercise.
Peter Woit, who wrote a scathing (but insightful (and inciteful)) critique of string theory "Not Even Wrong: The Failure of String Theory & the Continuing Challenge to Unify the Laws of Physics" (2006), attributed "so bad it isn't even wrong" to Wolfgang Pauli which matches my recollection, but I'm not sure from where. As I recall, Pauli used it to describe a physics paper that was so poorly thought out and abysmally written that he felt that to say that it was incorrect would be to grant it a certain degree of utterly undeserved and spurious authority.
Pauli is eminently quotable in a terribly charming way, but not having been able to find the quote itself, only an attribution of it, I have not placed it in the quotations section.
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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MoEnzyme
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Re:The Flipping Point
« Reply #234 on: 2009-07-19 19:54:35 » |
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For the denizens of this thread, I would like to point you to my new thread in the church doctrine section Apocalypse Now which I think is relevant to this topic; I would welcome any brief summaries of your positions as it fits into that thread. Its a more general topic as I see it, so feel free to continue hashing out the nuances of global warming here as well. Thanks, -Mo
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Hermit
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Re:The Flipping Point
« Reply #235 on: 2009-08-26 04:56:27 » |
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Exclusive: The methane time bomb
Arctic scientists discover new global warming threat as melting permafrost releases millions of tons of a gas 20 times more damaging than carbon dioxide
Sources: The Independent
Authors: Steve Connor (Science Editor, The Independent)
Dated: 2008-09-23
The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.
The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.
Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species. Scientists aboard a research ship that has sailed the entire length of Russia's northern coast have discovered intense concentrations of methane – sometimes at up to 100 times background levels – over several areas covering thousands of square miles of the Siberian continental shelf.
In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through "methane chimneys" rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a "lid" to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age.
They have warned that this is likely to be linked with the rapid warming that the region has experienced in recent years.
Methane is about 20 times more powerful as a greenhouse gas than carbon dioxide and many scientists fear that its release could accelerate global warming in a giant positive feedback where more atmospheric methane causes higher temperatures, leading to further permafrost melting and the release of yet more methane.
The amount of methane stored beneath the Arctic is calculated to be greater than the total amount of carbon locked up in global coal reserves so there is intense interest in the stability of these deposits as the region warms at a faster rate than other places on earth.
Orjan Gustafsson of Stockholm University in Sweden, one of the leaders of the expedition, described the scale of the methane emissions in an email exchange sent from the Russian research ship Jacob Smirnitskyi.
"We had a hectic finishing of the sampling programme yesterday and this past night," said Dr Gustafsson. "An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These 'methane chimneys' were documented on echo sounder and with seismic [instruments]."
At some locations, methane concentrations reached 100 times background levels. These anomalies have been seen in the East Siberian Sea and the Laptev Sea, covering several tens of thousands of square kilometres, amounting to millions of tons of methane, said Dr Gustafsson. "This may be of the same magnitude as presently estimated from the global ocean," he said. "Nobody knows how many more such areas exist on the extensive East Siberian continental shelves.
"The conventional thought has been that the permafrost 'lid' on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place. The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leak methane... The permafrost now has small holes. We have found elevated levels of methane above the water surface and even more in the water just below. It is obvious that the source is the seabed."
The preliminary findings of the International Siberian Shelf Study 2008, being prepared for publication by the American Geophysical Union, are being overseen by Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences. Since 1994, he has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane "hotspots", which have now been confirmed using more sensitive instruments on board the Jacob Smirnitskyi.
Dr Semiletov has suggested several possible reasons why methane is now being released from the Arctic, including the rising volume of relatively warmer water being discharged from Siberia's rivers due to the melting of the permafrost on the land.
The Arctic region as a whole has seen a 4C rise in average temperatures over recent decades and a dramatic decline in the area of the Arctic Ocean covered by summer sea ice. Many scientists fear that the loss of sea ice could accelerate the warming trend because open ocean soaks up more heat from the sun than the reflective surface of an ice-covered sea.
Hundreds of methane 'plumes' discovered
British scientists find more evidence of climate threat
Sources: The Independent
Authors: Steve Connor (Science Editor, The Independent)
Dated: 2008-09-25
British scientists have discovered hundreds more methane "plumes" bubbling up from the Arctic seabed, in an area to the west of the Norwegian island of Svalbard. It is the second time in a week that scientists have reported methane emissions from the Arctic.
Methane is 20 times more potent than carbon dioxide as a greenhouse gas and the latest findings from two separate teams of scientists suggest it is being released in significant amounts from within the Arctic Circle. [ Hermit : The "20 times" is a massive underestimate of the harm done by Methane (CH4, as it breaks down to CO2 another greenhouse and this was not taken into account in earlier models. The current value being used by the IPCC is that Methane is 72 times more potent than carbon dioxide as a greenhouse gas. ]
On Tuesday, The Independent revealed that scientists on board a Russian research ship had detected vast quantities of methane breaking through the melting permafrost under the seabed of the shallow continental shelf off the Siberian coast.
Yesterday, researchers on board the British research ship the James Clark Ross said they had counted about 250 methane plumes bubbling from the seabed in an area of about 30 square miles in water less than 400 metres (1,300 feet) deep off the west coast of Svalbard. They have also discovered a set of deeper plumes at depths of about 1,200 metres at a second site near by. Analysis of sediments and seawater has confirmed the rising gas is methane, said Professor Graham Westbrook of Birmingham University, the study's principal investigator.
"The discovery of this system is important as its presence provides evidence that methane, which is a greenhouse gas, has been released in this climactically sensitive region since the last ice age," Professor Westbrook said. An analysis of sediments taken from the seabed show that the gas is coming from methane hydrates – ice-like crystals where molecules of the gas are captured in "cages" made of water molecules, which become unstable as water pressures fall or temperatures rise.
Professor Westbrook said the area surveyed off the west coast of Svalbard was very different to the area being studied by the Russian vessel because the water was much deeper and does not have a layer of permafrost sealing the methane under the seabed.
It is likely that methane emissions off Svalbard have been continuous for about 15,000 years – since the last ice age – but as yet no one knows whether recent climactic shifts in the Arctic have begun to accelerate them to a point where they could in themselves exacerbate climate change, he said.
"We were very excited when we found these plumes because it was the first evidence there was an active gas system in this part of the world," Professor Westbrook said after disembarking from the ship, which arrived back in Britain yesterday. "Now we know it's there we know we have to very seriously consider its effect."
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Re:The Flipping Point
« Reply #236 on: 2009-09-05 20:16:16 » |
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Arctic temperatures are now higher than at any time in the last 2,000 years, research reveals.
Source: BBC.co.uk
Authors: Richard Black
Dated: 2009-09-03
Changes to the Earth's orbit drove centuries of cooling, but temperatures rose fast in the last 100 years as human greenhouse gas emissions rose.
Scientists took evidence from ice cores, tree rings and lake sediments.
Writing in the journal Science, they say this confirms that the Arctic is very sensitive both to changes in solar heating and to greenhouse warming.
The 23 sites sampled were good enough to provide a decade-by-decade picture of temperatures across the region.
The result is a "hockey stick"-like curve in which the last decade - 1998-2008 - stands out as the warmest in the entire series.
"The most pervasive signal in the reconstruction, the most prominent trend, is the overall cooling that took place for the first 1,900 years [of the record]," said study leader Darrell Kaufman from Northern Arizona University in Flagstaff, US.
"The 20th Century stands out in strong contrast to the cooling that should have continued. The last half-century was the warmest of the 2,000-year temperature record, and the last 10 years have been especially dramatic," he told BBC News.
On average, the region cooled at a rate of 0.2C per millennium until about 1900. Since then, it has warmed by about 1.2C.
Much debate on climate change has centred on the Mediaeval Warm Period, or Mediaeval Climate Anomaly - a period about 1,000 years ago when, historical records suggest, Vikings colonised Greenland and may have grown grapes in Newfoundland.
The new analysis shows that temperatures were indeed warmer in this region 1,000 years ago than they were 100 years ago - but not as warm as they are now, or 1,000 years previously.
"It shows that the Mediaeval Warm Period is real, and is... an exception from the general trend of cooling," commented Eystein Jansen from Bergen University in Norway, who was not involved in the research.
"It also shows there's lots of variability on the 100-year timescale, and that's probably more so in the Arctic than elsewhere."
Professor Jansen was a co-ordinating lead author on the palaeoclimate (ancient climate) chapter of the last Intergovernmental Panel on Climate Change (IPCC) assessment.
Arctic wobbles
The root cause of the slow cooling was the orbital "wobble" that slowly varies, over thousands of years, the month in which the Earth approaches closest to the Sun.
This wobble slowly decreased the total amount of solar energy arriving in the Arctic region in summertime, and the temperature responded - until greenhouse warming took over.
"The 20th Century is the first century for which how much energy we're getting from the Sun is no longer the most important thing governing the temperature of the Arctic," said another of the study team, Nicholas McKay from the University of Arizona.
The recent warming of the Arctic has manifested itself most clearly in the drastic shrinkage in summer sea-ice extent, with the smallest area in the satellite era documented in 2007.
As the Science study emerged, UN Secretary-General Ban Ki-moon was telling the World Climate Conference in Geneva that many of the "more distant scenarios" forecast by climate scientists were "happening now".
Earlier this week, Mr Ban visited the Arctic in an attempt to gain first-hand experience of how the region is changing.
"Scientists have been accused for years of scaremongering. But the real scaremongers are those who say we cannot afford climate action," he said in his Geneva speech, calling for world leaders to make bigger pledges of action in the run-up to December's UN climate summit in Copenhagen.
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Re:The Flipping Point
« Reply #237 on: 2009-09-05 20:55:02 » |
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Is There a Climate-Change Tipping Point?
Source: Time.com
Authors: Bryan Walsh
Dated: 2009-09-04
Global warming — the very term sounds gentle, like a bath that grows pleasantly hotter under the tap. Many people might assume that's how climate change works too, the globe gradually increasing in temperature until we decide to stop it by cutting our carbon emissions. It's a comforting notion, one that gives us time to gauge the steady impact of warming before taking action.
There's just one problem: that's not how climate change is likely to unfold. Instead, scientists worry about potential tipping points — triggers that, once reached, could lead to sudden and irrevocable changes in the climate, almost without warning. It's the same phenomenon of sudden collapse that can be seen in any number of complex systems that seem perfectly stable, until they're not — ecosystems, financial markets, even epileptic seizures. The trick is to identify the warning signs that indicate a tipping point — and collapse — are about to be reached and to take action to avoid them. (Read "Heroes of the Environment 2008.")
A new article in the Sept. 3 issue of Nature shows there may be ways to do this, since certain warning signals appear to be similar across a variety of complex systems. Researchers from Wageningen University, the University of Wisconsin and Scripps Institution of Oceanography found that an assortment of systems they studied all had critical thresholds that could trigger change from one state to another — changes that tend to be abrupt, not gradual. "Such threshold events don't happen that often, but they are extraordinarily important," says study co-author Stephen Carpenter of the University of Wisconsin. "They are the portals to change."
So, how do we know that change is at hand? The Nature researchers noticed one potential signal: the sudden variance between two distinct states within one system, known by the less technical term squealing. In an ecological system like a forest, for example, squealing might look like an alternation between two stable states — barren versus fertile — before a drought takes its final toll on the woodland and transforms it into a desert, at which point even monsoons won't bring the field back to life. Fish populations seem to collapse suddenly as well — overfishing causes fluctuations in fish stocks until it passes a threshold, at which point there are simply too few fish left to bring back the population, even if fishing completely ceases. And even in financial markets, sudden collapses tend to be preceded by heightened trading volatility — a good sign to pull your money out of the market. "Heart attacks, algae blooms in lakes, epileptic attacks — every one shows this type of change," says Carpenter. "It's remarkable." (See TIME's video: "Climate Central: Vanishing Salt Marshes.")
In climate terms, squealing may involve increased variability of the weather — sudden shifts from hot temperatures to colder ones and back again. General instability ensues and, at some point, the center ceases to hold. "Before we reached a climate tipping point we'd expect to see lots of record heat and record cold," says Carpenter. "Every example of sudden climate change we've seen in the historical record was preceded by this sort of squealing."
The hard part will be putting this new knowledge into action. It's true that we have a sense of where some of the tipping points for climate change might lie — the loss of Arctic sea ice, or the release of methane from the melting permafrost of Siberia. But that knowledge is still incomplete, even as the world comes together to try, finally, to address the threat collectively. "Managing the environment is like driving a foggy road at night by a cliff," says Carpenter. "You know it's there, but you don't know where exactly." The warning signs give us an idea of where that cliff might be — but we'll need to pay attention.
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Re:The Flipping Point
« Reply #238 on: 2009-10-05 11:42:41 » |
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Post-human Earth: How the planet will recover from us
Editorial: New Scientist, Magazine issue 2728
Earth will be OK, but for us it's not so good
It made for disturbing reading when we asked scientists to speculate on what the world would be like if the global average temperature rose by 4 °C. They were happy to oblige, and the results formed the basis of the cover story for our 28 February issue. Now climate scientists have firmed up their speculations with modelling studies, and their conclusions are, if anything, more worrying (see "No rainforest, no monsoon: get ready for a warmer world") A 4 °C rise would be a disaster.
It is not hard to imagine that if we fail to get a grip on the climate, civilisation will collapse altogether. So we asked another question: if we consume ourselves back to the Stone Age, what happens next? Would Earth recover? The answers paint a strangely comforting picture of our planet's future - but they don't leave a lot of room for us or our descendants.
Source: New Scientist, Magazine issue 2728
Authors: Bob Holmes Bob Holmes is a consultant for New Scientist based in Edmonton, Canada
Dated: 2009-09-30
WHEN Nobel prize-winning atmospheric chemist Paul Crutzen coined the word Anthropocene around 10 years ago, he gave birth to a powerful idea: that human activity is now affecting the Earth so profoundly that we are entering a new geological epoch.
The Anthropocene has yet to be accepted as a geological time period, but if it is, it may turn out to be the shortest - and the last. It is not hard to imagine the epoch ending just a few hundred years after it started, in an orgy of global warming and overconsumption.
Let's suppose that happens. Humanity's ever-expanding footprint on the natural world leads, in two or three hundred years, to ecological collapse and a mass extinction. Without fossil fuels to support agriculture, humanity would be in trouble. "A lot of things have to die, and a lot of those things are going to be people," says Tony Barnosky, a palaeontologist at the University of California, Berkeley. In this most pessimistic of scenarios, society would collapse, leaving just a few hundred thousand eking out a meagre existence in a new Stone Age.
Whether our species would survive is hard to predict, but what of the fate of the Earth itself? It is often said that when we talk about "saving the planet" we are really talking about saving ourselves: the planet will be just fine without us. But would it? Or would an end-Anthropocene cataclysm damage it so badly that it becomes a sterile wasteland?
The only way to know is to look back into our planet's past. Neither abrupt global warming nor mass extinction are unique to the present day. The Earth has been here before. So what can we expect this time?
Take greenhouse warming. Climatologists' biggest worry is the possibility that global warming could push the Earth past two tipping points that would make things dramatically worse. The first would be the thawing of carbon-rich peat locked in permafrost. As the Arctic warms, the peat could decompose and release trillions of tonnes of carbon into the atmosphere - perhaps exceeding the 3 trillion tonnes that humans could conceivably emit from fossil fuels. The second is the release of methane stored as hydrate in cold, deep ocean sediments. As the oceans warm and the methane - itself a potent greenhouse gas - enters the atmosphere, it contributes to still more warming and thus accelerates the breakdown of hydrates in a vicious circle.
"If we were to blow all the fossil fuels into the atmosphere, temperatures would go up to the point where both of these reservoirs of carbon would be released," says oceanographer David Archer of the University of Chicago. No one knows how catastrophic the resulting warming might be.
That's why climatologists are looking with increasing interest at a time 55 million years ago called the Palaeocene-Eocene thermal maximum, when temperatures rose by up to 9 °C in a few thousand years - roughly equivalent to the direst forecasts for present-day warming. "It's the most recent time when there was a really rapid warming," says Peter Wilf, a palaeobotanist at Pennsylvania State University in University Park. "And because it was fairly recent, there are a lot of rocks still around that record the event."
By measuring ocean sediments deposited during the thermal maximum, geochemist James Zachos of the University of California, Santa Cruz, has found that the warming coincided with a huge spike in atmospheric CO2. Between 5 and 9 trillion tonnes of carbon entered the atmosphere in no more than 20,000 years (Nature, vol 432, p 495). Where could such a huge amount have come from?
Volcanic activity cannot account for the carbon spike, Zachos says. Instead, he blames peat decomposition, which would have happened not from melting permafrost - it was too warm for permafrost - but through climatic drying. The fossil record of plants from this time testifies to just such a drying episode.
Carbon spike
If Zachos and colleagues are right, then 55 million years ago Earth passed through a carbon crisis very much like the one feared today: a sudden spike in CO2, followed by a runaway release of yet more greenhouse gases. What happened next may give us a glimpse of what to expect if our current crisis hits full force.
Geochemists have long known that when a pulse of CO2 enters the air, much of it quickly dissolves in the upper layer of the ocean before gradually dispersing through deeper waters. Within a few centuries, an equilibrium is reached, with about 85 per cent of the CO2 dissolved in the oceans and 15 per cent in the atmosphere. This CO2 persists for tens or hundreds of thousands of years - what Archer believes will be the "long tail" of the Anthropocene. Until recently, though, climate modellers were a bit fuzzy on what this tail would look like.
"Until we had some case studies from the past, there was always some degree of uncertainty in the models," says Zachos. His studies are beginning to clear up these doubts. Carbonate rocks laid down on the sea floor during the carbon spike, for example, reveal that the oceans quickly became very acidic (Science, vol 308, p 1611). But this extreme acidification lasted just 10,000 or 20,000 years, barely a blink of an eye by geological standards, after which the oceans returned to near-normal conditions for the next 150,000 years. Even the stores of peat and methane hydrates must have regenerated within 2 million years, Zachos says, because at that time the planet underwent another, smaller carbon crisis, which must also have involved peat or methane hydrates. That suggests that the long tail of the Anthropocene is unlikely to last longer than 2 million years - still not long at all by geological standards.
However, today's carbon spike differs from that of the late Palaeocene in one important way: our planet is much cooler than it was back then, so warming is likely to have a more profound effect. During the late Palaeocene, the world was warm and largely ice-free. Now we have bright, shiny ice caps which reflect sunlight back into space. These will melt, giving way to dark, energy-absorbing rock and soil. And with all that meltwater, sea levels will rise and permafrost will thaw more rapidly, boosting warming still further.
This extra nudge could conceivably tip the Earth out of its present cycle of glacials and interglacials and return it to an older, warmer state. "The Earth was ice-free for many millions of years. The current ice ages started only about 35 million years ago, so we might kick ourselves out of that," says Pieter Tans, an atmospheric scientist at the US National Oceanic and Atmospheric Administration in Boulder, Colorado. Even so, the newly ice-free world would merely be reverting to a familiar state. On this reading of the evidence, even the most drastic climate catastrophe would have little chance of pushing the Earth's physical systems into uncharted territory.
Not so, says James Hansen, director of NASA's Goddard Institute for Space Studies. He argues that past episodes are a poor guide to what will happen in the future, for the simple reason that the sun is brighter now than it was then. Add that to the mix and the release of methane hydrates could lead to catastrophic, unstoppable global warming - a so-called "Venus syndrome (PDF)" that causes the oceans to boil away and dooms the Earth to the fate of its broiling neighbour.
So much for the Earth itself - what of life? If Hansen is right, Earth is heading for sterility. But if the lesser scenario plays out instead, it's a very different story.
Conservation biologists say we may already be in the midst of an extinction event that could potentially turn into one of the greatest mass extinctions ever - one that would alter the trajectory of evolution.
Oddly enough, the climatic turmoil of the thermal maximum led to very little loss of biodiversity. "Nobody has ever picked the Palaeocene-Eocene boundary as a major extinction interval. It's not even in the second tier," says Scott Wing, a palaeobotanist at the Smithsonian Institution in Washington DC. Instead, the fossil record shows that species simply migrated, following their preferred climate across the globe.
Today, of course, that is often not possible because roads, cities and fields have fragmented so many natural habitats. Polar and alpine species may find their habitat vanishes entirely, and this is not to mention all the other ways people imperil species.
"We're a perfect storm as far as biodiversity is concerned," says David Jablonski, a palaeontologist at the University of Chicago. "We're not just overhunting and overfishing. We're not just changing the chemistry of the atmosphere and acidifying the oceans. We're not just taking the large-bodied animals. We're doing all this stuff simultaneously." Even so, Jablonski thinks humans are unlikely to be capable of causing an extinction comparable to the one at the end of the Permian, 251 million years ago, when an estimated 96 per cent of all marine species and 70 per cent of terrestrial ones bit the dust.
Whether the Anthropocene mass extinction eventually ranks with the Permian or with lesser ones, it would still reshuffle the evolutionary deck. Once again, the past gives us some idea of what we could expect.
The fossil record tells us that every mass extinction plays out differently, because each has its own unique causes. However, there is one common factor: the species at greatest risk are those with the narrowest geographic ranges. Jablonski's studies of fossil marine snails show that species with planktonic larvae - which disperse widely - fare better than species with a more restricted distribution (Science, vol 279, p 1327).
Cockroach world
Add to that massive habitat disturbances, says Jablonski, and a picture emerges of life after the Anthropocene extinction. Small body sizes, fast reproductive rates and an ability to exploit disturbed habitats will all prove advantageous. "It's a rats, weeds and cockroaches kind of world," says Jablonski.
The wave of extinctions is likely to sweep through species in a fairly predictable way. "First we would probably lose the species that are already endangered, then it would work its way down," says Barnosky. "Eventually it would hit some of the species that we don't consider at risk today - for example, many of the African herbivores that today seem to have healthy populations."
However, predictions about the fate of any particular species are almost impossible, as luck will also play a role. The survivors will probably be a more-or-less random selection of weedy plants and opportunistic animals, notes Doug Erwin, a palaeobiologist at the Smithsonian Institution.
If the Anthropocene does end with a mass extinction, the fossil record tells us a lot about what the recovery might look like. Whether the news is good or bad depends on your perspective. "Recoveries from mass extinctions are geologically rapid, but from a human point of view grindingly long. We're talking millions of years," says Jablonski.
Immediately after a mass extinction, the fossil evidence suggests that ecosystems go into a state of shock for several million years. For many millions of years after the Permian extinction, for example, marine environments the world over were dominated by the same 25 or 30 species. "It's pretty boring," says Erwin.
Something similar happened on land after the Cretaceous extinction. Pre-extinction plant fossils from western North America testify to flourishing ecosystems, with a variety of insects feeding on a wide assortment of plants. After the extinction, though, both plant and insect diversity drops dramatically, with some insect feeding methods vanishing almost completely.
After that, confusion reigns for 10 million years. There are fossil assemblages with only a few insects and plants, ones with many insects but few plants, others with many plants but few insects - just about everything except what ecologists would call "normal" (Science, vol 313, p 1112). "At no time did we have what I would call a healthy ecosystem, with diverse insects feeding on diverse plants," says Wilf. All the while biodiversity remains low, with few new species evolving. "You're just trying to hang on," says Erwin.
A study of marine fossil diversity bears this out. Nearly a decade ago, James Kirchner of the University of California, Berkeley, and Anne Weil of Duke University in Durham, North Carolina, took a database of all known marine fossils and used it to work out how closely peaks of speciation follow peaks of extinction (Nature, vol 404, p 177). "We went into this thinking, like everybody else, that when you have an extinction, you begin repopulating almost immediately," says Kirchner, now at the Swiss Federal Institute for Forest, Snow and Landscape Research in Birmensdorf. Instead, they found that speciation peaks lagged about 10 million years behind extinction peaks. "We pretty much fell out of our chairs," he says.
In fact, for the first few million years after an extinction the speciation rate actually falls. "That suggests to us a sort of wounded biosphere. Extinction events don't just remove organisms from an ecosystem, leaving lots of opportunity for new species to diversify. Instead, what we think happens is that the niches themselves collapse, so you won't have new organisms emerging to occupy them. The niches themselves don't exist any more," says Kirchner.
Eventually, though, evolution wins the day, and after a few tens of millions of years biodiversity rebounds. Sometimes, as after the Ordovician mass extinction 440 million years ago, the new regime looks a lot like the old one. But more often a new world emerges. "You're not re-establishing the old chessboard, you're designing a whole new game," says Erwin.
In the Permian, the oceans were dominated by filter-feeding animals such as brachiopods and sea lilies, which lived their whole lives attached to the bottom. Predators were rare. All that changed after the extinction, leaving a more dynamic and richer ecosystem. "From my point of view, the end-Permian mass extinction was the best thing that ever happened to life," says Erwin.
In a perverse way, then, the bottom line is an encouraging one. Even if we manage to overpopulate and overconsume ourselves back to the Stone Age, the Earth will probably survive. Life will go on. By the time the long tail of the Anthropocene is over, what little was left of humanity will probably be gone. A new geological age will dawn. Shame there won't be anybody around to give it a name.
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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the.bricoleur
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Re:The Flipping Point
« Reply #239 on: 2009-10-11 06:47:31 » |
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What happened to global warming?
By Paul Hudson
Climate correspondent, BBC News
SOURCE: BBC News
This headline may come as a bit of a surprise, so too might that fact that the warmest year recorded globally was not in 2008 or 2007, but in 1998.
But it is true. For the last 11 years we have not observed any increase in global temperatures.
And our climate models did not forecast it, even though man-made carbon dioxide, the gas thought to be responsible for warming our planet, has continued to rise.
So what on Earth is going on?
Climate change sceptics, who passionately and consistently argue that man's influence on our climate is overstated, say they saw it coming.
They argue that there are natural cycles, over which we have no control, that dictate how warm the planet is. But what is the evidence for this?
During the last few decades of the 20th Century, our planet did warm quickly.
Sceptics argue that the warming we observed was down to the energy from the Sun increasing. After all 98% of the Earth's warmth comes from the Sun.
But research conducted two years ago, and published by the Royal Society, seemed to rule out solar influences.
The scientists' main approach was simple: to look at solar output and cosmic ray intensity over the last 30-40 years, and compare those trends with the graph for global average surface temperature.
And the results were clear. "Warming in the last 20 to 40 years can't have been caused by solar activity," said Dr Piers Forster from Leeds University, a leading contributor to this year's Intergovernmental Panel on Climate Change (IPCC).
But one solar scientist Piers Corbyn from Weatheraction, a company specialising in long range weather forecasting, disagrees.
He claims that solar charged particles impact us far more than is currently accepted, so much so he says that they are almost entirely responsible for what happens to global temperatures.
He is so excited by what he has discovered that he plans to tell the international scientific community at a conference in London at the end of the month.
If proved correct, this could revolutionise the whole subject.
Ocean cycles
What is really interesting at the moment is what is happening to our oceans. They are the Earth's great heat stores.
According to research conducted by Professor Don Easterbrook from Western Washington University last November, the oceans and global temperatures are correlated.
The oceans, he says, have a cycle in which they warm and cool cyclically. The most important one is the Pacific decadal oscillation (PDO).
For much of the 1980s and 1990s, it was in a positive cycle, that means warmer than average. And observations have revealed that global temperatures were warm too.
But in the last few years it has been losing its warmth and has recently started to cool down.
These cycles in the past have lasted for nearly 30 years.
So could global temperatures follow? The global cooling from 1945 to 1977 coincided with one of these cold Pacific cycles.
Professor Easterbrook says: "The PDO cool mode has replaced the warm mode in the Pacific Ocean, virtually assuring us of about 30 years of global cooling."
So what does it all mean? Climate change sceptics argue that this is evidence that they have been right all along.
They say there are so many other natural causes for warming and cooling, that even if man is warming the planet, it is a small part compared with nature.
But those scientists who are equally passionate about man's influence on global warming argue that their science is solid.
The UK Met Office's Hadley Centre, responsible for future climate predictions, says it incorporates solar variation and ocean cycles into its climate models, and that they are nothing new.
In fact, the centre says they are just two of the whole host of known factors that influence global temperatures - all of which are accounted for by its models.
In addition, say Met Office scientists, temperatures have never increased in a straight line, and there will always be periods of slower warming, or even temporary cooling.
What is crucial, they say, is the long-term trend in global temperatures. And that, according to the Met office data, is clearly up.
To confuse the issue even further, last month Mojib Latif, a member of the IPCC (Intergovernmental Panel on Climate Change) says that we may indeed be in a period of cooling worldwide temperatures that could last another 10-20 years.
Professor Latif is based at the Leibniz Institute of Marine Sciences at Kiel University in Germany and is one of the world's top climate modellers.
But he makes it clear that he has not become a sceptic; he believes that this cooling will be temporary, before the overwhelming force of man-made global warming reasserts itself.
So what can we expect in the next few years?
Both sides have very different forecasts. The Met Office says that warming is set to resume quickly and strongly.
It predicts that from 2010 to 2015 at least half the years will be hotter than the current hottest year on record (1998).
Sceptics disagree. They insist it is unlikely that temperatures will reach the dizzy heights of 1998 until 2030 at the earliest. It is possible, they say, that because of ocean and solar cycles a period of global cooling is more likely.[bricoleur - let the experiement begin. I'll report back to this post in 2015]
One thing is for sure. It seems the debate about what is causing global warming is far from over. Indeed some would say it is hotting up.
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