Marlowe Hood Yahoo News 10 Mar 09;
COPENHAGEN (AFP) – Months before make-or-break climate negotiations, a conclave of scientists warned Tuesday that the impact of global warming was accelerating beyond a forecast made by UN experts two years ago.
Sea levels this century may rise several times higher than predictions made in 2007 that form the scientific foundation for policymakers today, the meeting heard.
In March 2007, the UN's Intergovernmental Panel on Climate Change (IPCC) concluded that global warming, if unchecked, would lead to a devastating amalgam of floods, drought, disease and extreme weather by the century end.
The world's oceans would creep up 18 to 59 centimetres (7 to 23 inches), enough to wipe out several small island nations, and wreak havoc for tens of millions living in low-lying deltas in east Asia, the Indian subcontinent and Africa.
But a new study, presented at the Copenhagen meeting on Tuesday, factored in likely water runoff from disintegrating glaciers in Greenland and Antarctica, and found the rise could be much higher.
The IPCC estimate had been based largely on the expansion of oceans from higher temperatures, rather than meltwater and the impact of glaciers tumbling into the sea.
Using the new model, "we get a range of sea level rise by 2100 between 75 and 190 centimetres when we apply the IPCC's temperature scenarios for the future," said climate expert Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research.
Even if the world manages to dramatically cut the emission of greenhouse gases driving global warming, the "best estimate" is about one metre (3.25 feet), he said.
"A few years ago, those of us who talked about the impact of the ice sheets were seen as extremists. Today it is recognized as the central issue," said glaciologist Eric Rignot of the University of California at Irvine.
"The world has very little time," IPCC chief Rajendra Pachauri told the meeting after the new findings were presented.
Participants also spoke out about fears that greenhouse gases -- mainly emissions from oil, gas and coal -- could trigger tipping points that would be nearly impossible to reverse.
The shrinking of the Arctic ice cap, and the release of billions of tonnes of greenhouse gases trapped in melting permafrost are two such "positive feedbacks" that could become both cause and consequence of global warming.
"We need to look at what is a 'reasonable worst case' in the lifetime of people alive today," said John Ashton, Britain's top climate negotiator, noting even rich nations had yet to take such scenarios seriously.
"A sea level rise of one or two meters would not just be damaging for China, it would be an absolute catastrophe. And what is catastrophic for China is catastrophic for the world," he said.
Up to 600 million people living close to coast lines in poor and rich countries alike could be affected, said Konrad Steffen, head of the Cooperative Institute for Research in Environmental Sciences in Boulder, Colorado.
"They will have to move -- it would change the whole structure of populations, and we know had badly we deal with migration," he told AFP.
Among the worst hit countries will be Bangladesh, which would lose some 17 percent of its landmass, displacing nearly 15 million people.
"These startling new predictions on sea levels rise spell disaster for millions of the world's poorest people," said Rob Bailey of Oxfam. "This must be a wakeup call for rich countries are not doing anywhere near enough to prevent these cataclysmic predictions becoming a reality."
More than 2,000 researchers from 80 countries responded to the open invitation to present their findings, which were then vetted by a panel of climate experts, many of them top figures in the IPCC.
"I and a lot of scientists see this meeting as an opportunity to update the science that has come out since the last IPCC report," said William Howard, a researcher from the University of Tasmania in Hobart, Australia.
"The huge response from scientists comes from a sense of urgency, but also a sense of frustration," said Katherine Richardson, head of the Danish government's Commission on Climate Change Policy.
Richardson said the 2007 IPCC report, called the Fourth Assessment Report, was an invaluable document but it would be years out of date when negotiators convene in Copenhagen in December to hammer out a global climate treaty.
Sea Levels Rising Faster Than Expected: Scientists
Gelu Sulugiuc, PlanetArk 11 Mar 09;
COPENHAGEN - The U.N.'s climate change panel may be severely underestimating the sea-level rise caused by global warming, climate scientists said on Monday, calling for swift cuts in greenhouse emissions.
"The sea-level rise may well exceed one meter (3.28 feet) by 2100 if we continue on our path of increasing emissions," said Stefan Rahmstorf, professor at the Potsdam Institute for Climate Impact Research. "Even for a low emission scenario, the best estimate is about one meter."
Rahmstorf spoke at the International Scientific Congress on Climate Change in Copenhagen.
The U.N.'s Intergovernmental Panel on Climate Change in 2007 predicted global warming would cause sea levels to rise by between 18 cm and 59 cm (7 inches and 23 inches) this century.
The IPCC said at the time the estimate could not accurately take into account factors such as the melting of ice sheets in Greenland and Antarctica. Many scientists criticized the number as too conservative.
"The ice loss in Greenland shows an acceleration during the last decade," said veteran Greenland researcher Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder.
"The upper range of sea-level rise by 2100 might be above one meter or more on a global average, with large regional differences depending where the source of ice loss occurs," he said.
John Church, a researcher at the Center for Australian Weather and Climate Research in Hobart, said rising oceans will lead to more frequent devastating floods in coastal areas.
The faster humans limit carbon dioxide emissions, the greater the chance to avoid the most extreme scenarios, he said.
"We could pass a threshold during the 21st century that can commit the world to meters of sea-level rise," he said. "Short-term emission goals are critical."
Early reductions of emissions are much more effective than actions later in the century, the scientists said.
"With stiff reductions in 2050 you can end the temperature curve (rise) quite quickly, but there's not much you can do to the sea-level rise anymore," Rahmstorf said. "We are setting in motion processes that will lead to sea levels rising for centuries to come."
(Editing by Mark Trevelyan)
Sea rise 'to exceed projections'
David Shukman, BBC News 10 Mar 09;
The global sea level looks set to rise far higher than forecast because of changes in the polar ice-sheets, a team of researchers has suggested.
Scientists at a climate change summit in Copenhagen said earlier UN estimates were too low and that sea levels could rise by a metre or more by 2100.
The projections did not include the potential impact of polar melting and ice breaking off, they added.
The implications for millions of people would be "severe", they warned.
Ten per cent of the world's population - about 600 million people - live in low-lying areas.
The UN's Intergovernmental Panel on Climate Change (IPCC), in its 2007 Fourth Assessment Report, had said that the maximum rise in sea level would be in the region of 59cm.
Professor Konrad Steffen from the University of Colorado, speaking at a press conference on Tuesday, highlighted new studies into ice loss in Greenland, showing it has accelerated over the last decade.
Professor Steffen, who has studied the Arctic ice for the past 35 years, told me: "I would predict sea level rise by 2100 in the order of one metre; it could be 1.2m or 0.9m.
"But it is one metre or more seeing the current change, which is up to three times more than the average predicted by the IPCC."
"It is a major change and it actually calls for action."
Dr John Church of the Centre for Australian Weather and Climate Research added: "The most recent research showed that sea level is rising by 3mm a year since 1993, a rate well above the 20th century average."
Ice flow
Professor Eric Rignot, a senior research scientist at Nasa's Jet Propulsion Laboratory, said that results gathered since the IPCC showed that melting and ice loss could not be overlooked.
"As a result of the acceleration of outlet glaciers over large regions, the ice sheets in Greenland and Antarctica are already contributing more and faster to sea level rise than anticipated," he observed.
Professor Stefan Ramstorf of the Potsdam Institute for Climate Impact Research said: "Based on past experience, I expect that sea level rise will accelerate as the planet gets hotter."
The forecasts by the team of scientists are critically important for coastal communities.
At Lowestoft, on the UK's east coast, the Environment Agency official in charge of coastal protection, David Kemp, said that even small rises in sea level could be overwhelming.
"Put bluntly, if it's 10cm below the height of the defence, then there's no problem," he told me.
"But if it's 10cm above the defence, then we could be looking at devastation.
"It looks very benign today but the North Sea can turn into a very ferocious beast."
Sea level rise could bust IPCC estimate
Catherine Brahic, Copenhagen, New Scientist 10 Mar 09;
Sea level rises could bust official estimates – that's the first big message to come from the climate change congress that kicked off in Copenhagen, Denmark, today.
Researchers, including John Church of the Centre for Australian Weather and Climate Research, presented evidence that Greenland and Antarctica are losing ice fast, contributing to the annual sea-level rise. Recent data shows that waters have been rising by 3 millimetres a year since 1993.
Church says this is above any of the rates forecast by the IPCC models. By 2100, sea levels could be 1 metre or more above current levels, he says. And it looks increasingly unlikely that the rise will be much less than 50 centimetres.
In 2007, the Intergovernmental Panel on Climate Change forecast a rise of 18 cm to 59 cm by 2100. But the numbers came with a heavy caveat that often went unnoticed by the popular press.
Flooding increase
Because modelling how the Greenland and Antarctic ice sheets will react to rising temperatures is fiendishly complicated, the IPCC did not include either in its estimate. It's no small omission: the Greenland ice cap, the smaller and so far less stable of the two, holds enough water that if it all melted, it would raise sea levels by 6 metres on average across the globe.
"As a result of the acceleration of outlet glaciers over large regions, the ice sheets in Greenland and Antarctica are already contributing more and faster to sea level rise than anticipated," says Eric Rignot of the University of California in Irvine and NASA's Jet Propulsion Laboratory. "If this trend continues, we are likely to witness sea level rise 1 metre or more by year 2100", he says.
Church says even 50 cm would have a huge effect on flooding events. "Our study on Australia showed that coastal flooding events that today we expect only once every 100 years will happen several times a year by 2100," he says.
Jason Lowe of the UK Met Office remains cautious. He accepts that recent data shows ice from Greenland and Antarctica is rapidly pushing up sea levels, but says the models simply are not yet sophisticated enough to say how this affects the future.
