Global warming is „very likely” caused by humans, and temperatures and sea-levels will increase by the end of the century, the UN said in its most comprehensive report yet on climate change.
Temperatures are likely to rise by 1.1 to 6.4 degrees Celsius by the end of this century relative to the last, with a probable 2 to 4.5 degree range if carbon dioxide doubles from pre-industrial levels, the United Nations Intergovernmental Panel on Climate Change said in the report. Sea-level gain over the same period may range from 18 to 59 centimeters (7 to 23 inches), it said. The Bush administration said the role of human activity in climate change is no longer up for debate following the report. „Human activity is contributing to changes in the Earth's Climate,” Energy Secretary Samuel Bodman said at a press conference in Washington. „That issue is no longer up for debate.” A key change in the report's language compared with the panel's 2001 document showed there is more certainty that human activity is causing the warming. The report, released to reporters in Paris, puts the probability of the link at more than 90%, against the 66 to 90% likelihood signaled in 2001. „Clearly we are endangering all species on earth, we are endangering the future of the human race,” IPCC chairman Rajendra Pachauri said in an interview. „We are probably beyond the stage where we could have called it urgent. I would say it is immediate,” said Pachauri, referring to the need for governments to act to reduce emissions.
„This report puts a full stop behind the questioning of the science underlying the issue of whether humans are causing global warming,” Achim Steiner, director of the UN Environment Program, said in an interview in Paris. „This is critical because it allows us to now to shift the attention to what kind of policy responses and international initiatives we need to achieve emissions reductions.” The global atmospheric concentration of carbon dioxide (CO2) stood at 379 parts per million in 2005, up from about 280 ppm in 1750, before the industrial revolution, the report said. Concentrations of CO2, and methane, another greenhouse gas, exceed „by far” the highest in an Antarctic ice-core record stretching back 650,000 years. Scientists have said global warming caused by man-made emissions is responsible for melting glaciers and ice sheets, and increased instances of storms, droughts and floods. Over this century, those effects may be magnified, according to today's report. „Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global system during the 21st century that would very likely be larger than those observed during the 20th century,” the report said. The increases in greenhouse gases are primarily attributable to fossil fuel use and land-use change, Susan Solomon, who chaired talks this week, said at a Paris news conference.
„This is a statement by the largest scientific panel ever put together on a major scientific issue that we now have the smoking gun on global warming,” said Philip Clapp, president of the US National Environmental Trust in a January 31 phone interview after seeing portions of the draft. Today's report, „Climate Change 2007: the Physical Science Basis,” is the first in a four-volume survey that involves more than 2,500 scientists from over 130 countries. Governmental delegations and scientists went over the wording of today's report line-by-line, in talks that ended past midnight last night in Paris. On the rise in sea-levels, language was added to the statement to reflect concerns that the new forecast doesn't bear in mind recent discoveries and so underestimates the potential, said Sharon Hays, associate director of the US Office of Science and Technology Policy, in a telephone interview today.
„The concern was that the current models don't take into account the melting and break-up of the ice that we're currently seeing,” Hays said. The wording of the document reads: „dynamical processes related to ice flow not included in current models, but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea-level rise.” „Scientists at the University of Texas at Austin on August 10 said in the journal Science that melting of Greenland's ice sheet „increased dramatically” in the past few years, with one portion losing ice five times faster in the past two years than the previous year and a half. The breakup in 2002 of the Larsen B ice shelf opened the way for the west Antarctic ice sheet's glaciers to flow faster, accelerating melting. „A number of scientists are now saying the west Antarctic ice sheet is the awakened giant of climate change, and that is the truly catastrophic risk,” Clapp said.
Overall, the IPCC is signaling „more urgency” on sea-level changes, melting glaciers ice caps and sea ice, one of the report's editors, Roger Barry, said in a January 26 interview. Barry is director of the US National Snow and Ice Data Center in Boulder, Colorado. The full temperature range across all scenarios examined by the IPCC was for a rise of 1.1 to 6.4 degrees Celsius, and „best estimates,” which weren't given in 2001, for each scenario ranged from 1.8 to 4 degrees, showing a greater degree of certainty about climate change. The 2001 range was for a 1.4 to 5.8 degrees Celsius rise. „We have greater certainty, and that should worry us more,” UNEP's Steiner said. „These things are more likely to now happen.” Steiner and environmental groups including WWF International, Greenpeace and Friends of the Earth said that now the causes of global warming have been established with near certainty, governments need to act to halt greenhouse gas emissions. Many industrialized nations have already begun taking action by setting caps on emissions. Under the UN's Kyoto Protocol treaty, 35 countries and the European Union agreed to cut emissions of greenhouse gases by a combined 5% from 1990 levels by the 2008-2012 period.
The US, the largest emitter of greenhouse gases, and Australia didn't ratify the treaty, and developing nations such as India and China aren't subject to emissions reductions. US President George W. Bush „has put in place a comprehensive set of policies aimed at addressing what he himself has called a very serious problem,” Hays, the US negotiator, said. „The Kyoto treaty was flawed and we believe that our policies are the right ones.” In 2002, Bush set out plans to reduce greenhouse gas intensity - the emissions per unit of GDP - by 18% by 2012 - preventing the release of more than 500 million metric tons of CO2. The top US climate change negotiator, Harlan Watson, told Bloomberg in November that the US is a „little ahead of schedule” on achieving that goal, which would still see total US emissions 30% above 1990 levels, compared with the seven percent reduction Kyoto would have set for the country. (Bloomberg)