By Cheryl Pellerin
February 13, 2007
Co-authors of the latest report of the U.N. Intergovernmental Panel on Climate Change (IPCC) -- a group of government representatives that commissions assessments of climate change every five years -- discussed this and other findings February 8th before the House of Representatives Committee on Science and Technology.
"Essentially, what we've done in the IPCC, perhaps as a medical analogy, is to do a diagnosis of the vital signs of the planet Earth," said co-author Kevin Trenberth of the U.S. National Center for Atmospheric Research. "What we found is that the planet is running a fever and the prognosis is that it's apt to become much worse."
The IPCC was established by the World Meteorological Organization (WMO) and the U.N. Environment Programme to assess the scientific, technical and socio-economic information needed to understand climate change and its impacts. It is open to all United Nations and WMO members.
The reports, prepared by hundreds of climate scientists from around the world, provide a comprehensive view of the current human understanding of climate science and climate change. Major assessments were made in 1990, 1995 and 2001.
The latest, the Fourth Assessment Report of the IPCC, has three working groups and a task force on greenhouse gas inventories. Working Group I assesses the science of climate change; Working Group II assesses climate change impacts, adaptation and vulnerability; Working Group III assesses climate change mitigation.
The reports of working groups II and III will be released in spring 2007; a report that contains a synthesis of findings from all three working groups is due in November.
DATA AND DATA GAPS
At the hearing, lead report authors summarized their findings for the committee. A growing body of evidence, they said, shows discernible, physically consistent changes.
These include increases in global average air temperature and atmospheric temperatures above the surface, increases in surface and subsurface ocean water temperature, widespread melting of snow, decreases in Arctic sea-ice extent and thickness, decreases in glacier and small ice-cap extent and mass, and rising global mean sea level.
Progress in understanding how the climate is changing, Trenberth said, comes from improved and extended data sets and data analyses, broader geographical coverage, better understanding of uncertainties and a wider variety of measurements.
Global warming will continue to occur in the near future, said co-author Susan Solomon, senior scientist at the National Oceanic and Atmospheric Administration's Earth System Research Laboratory, "even if we were to stabilize all greenhouse gases now instead of having continuing increases."
The greatest uncertainty so far involves the ice sheets of Greenland and Antarctica and their great potential to change sea levels.
An ice sheet is a 3.2-kilometer-thick, continentwide pile of snow that has been squeezed to ice under its own weight and spreads out under its own weight. As a result of spreading, the edges of the ice sheet thin, become ice shelves, then break off and become icebergs, said co-author Richard Alley of Pennsylvania State University.
In a warming world, the ice shelves, already in contact with the ocean, can melt very easily underneath, but scientists do not have a good understanding of the process.
"Improved understanding of many aspects of [warming and ice loss] is reflected in the new report," Alley said, "but there are unexpected changes in ice flow that have occurred for which we lack a scientific basis to provide accurate estimates."
This gap in understanding is important, said co-author Gerald Meehl, senior scientist at the National Center for Atmospheric Research, because "additional sea level rise from this source by the end of the 21st century could add another 10-20 centimeters to the upper range [60 centimeters], and higher future sea level rise values cannot be excluded."
U.S. REPONSE TO CLIMATE CHANGE
"President Bush devoted a significant portion of his State of the Union address in January to the subject of climate change and to what the United States intends to do about it," said Kurt Volker, principal deputy assistant secretary of state for European and Asian affairs, during a February 12 presentation to the German Marshall Fund in Berlin.
In the speech, Volker said, Bush set "mandatory targets that will make a real difference in meeting the challenges of climate change and energy security."
The plan seeks to reduce U.S. gasoline use in 2017 by 20 percent as compared to currently projected use estimates, thus reducing the projected growth of carbon dioxide emissions from transportation sources, which accounted for more than 22 percent of such emissions in 2004. The plan also seeks to raise the mandatory fuels standard to require the use of 132.5 billion liters of renewable and alternative fuels by 2017.
The measures announced in the State of the Union address, if adopted, could cut annual carbon dioxide emissions by 10 percent, around 175 million metric tons, by 2017. That reduction would be equivalent to that achieved by taking 26 million automobiles off the road.
"President Bush's plan builds on a long record of action on global climate change that all too often goes overlooked," Volker said.
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