James Randerson, guardian.co.uk 16 Dec 08;
Sea level rise due to global warming will "substantially exceed" official UN projections and could top 150cm by the end of the century, according to a report from the US Geological Survey on the risks of abrupt climate change. Such a rise would be catastrophic, seeing hundreds of millions of people affected by flooding.
Many scientists now fear the warming world is on the verge of "tipping points", in which climate change and its effects accelerate rapidly. The science is evolving quickly and the new report updates the most recent findings of the UN's Intergovernmental Panel on Climate Change (IPCC), which was released in 2007.
Some observers have called for an update of the science before the UN talks on a global deal on greenhouse gases emissions reach their finale in December 2009. The US report considers four scenarios for abrupt change, and delivers bad news on two.
On sea level, the report found models used by the IPCC in 2007 do not take into account recent information on how fast glaciers slide into the oceans, particularly from Greenland and the West Antarctic ice sheets. The report says the south western states of the US will enter a "permanent drought state".
But the risk of the ocean circulation in the Altantic shutting down – freezing the coasts of America and Europe, as in the film The Day After Tomorrow – is rated as low by the report. It predicts a slowdown of around 25% to 30%. The chance of a catastrophic release of methane from frozen sub-sea stores at high latitudes is also rated low. The report is part of a series by the US Climate Change Science Program, which collates all US federal research on the subject. It was presented tonight at the American Geophysical Union meeting in San Francisco.
The IPCC predicted that sea level would rise by 28cm to 42cm by the end of the century. ,The authors cite a 2007 study by Prof Stephan Rahmstof at the Potsdam Institute for Climate Change Research which predicted a sea level rise of between 40cm-150cm by 2100. But even this much higher estimate will "likely need to be revised upwards" because it does not fully capture the ice flow processes.
Seas will rise faster than predicted, say scientists
Frank Pope, The Times 16 Dec 08;
Sea levels will rise much faster than previously forecast because of the rate that glaciers and ice sheets are melting, a study has found.
Research commissioned by the US Climate Change Science Program concludes that the rises will substantially exceed forecasts that do not take into account the latest data and observations.
The adjusted outlook, announced at a meeting of the American Geophysical Union in San Francisco, suggests that recent predictions of a rise of between 7in and 2ft over the next century are conservative.
The study predicts that sea level rises will be far higher than the levels that were set out last year by the Inter-governmental Panel on Climate Change. The research looked at prehistoric periods when the climate changed dramatically over the course of decades, and evaluated the mechanisms behind such rapid transformation. Rising sea levels were one of the major elements involved in past episodes, along with faster glacial melting, droughts and changes to the Atlantic Ocean’s heat-driven circulation.
The report also concludes that some changes will not be as bad as first thought. It says, for example, that rapid releases of methane stored in permafrost and on the seabed may be less likely than feared.Other forecasts include a severe and permanent drought in the American West. The authors state that they are “among the greatest natural hazards facing the United States and the globe today” and call for “committed and sustained” monitoring of the forces that could trigger abrupt climate change.
Peter Clark, a professor of geosciences at Oregon State University and a lead author on the report, to be published in the journal Science, said: “If we don’t monitor the vital signs of the patient, then we’ll never be in a position to advise on the best course of action to take to ward off or prepare for the potentially devastating consequences.”
