By Elisabeth Rosenthal and Andrew C. Revkin
    The New York Times

    Friday 02 February 2007

    Paris - The world is already committed to centuries of warming, shifting weather patterns and rising seas from the atmospheric buildup of smokestack and tailpipe gases that trap heat, but warming can be substantially blunted with prompt action, an international network of climate experts said today.

    In a report released here today, the group, the Intergovernmental Panel on Climate Change of the United Nations, in its fourth assessment since 1990 of the causes and consequences of climate change, for the first time expressed with near certainty - more than 90 percent confidence - that carbon dioxide and other heat-trapping greenhouse gases were the main drivers of warming since 1950.

    In its last report, in 2001, the panel, consisting of hundreds of scientists and reviewers, put the confidence level at between 66 and 90 percent. Both reports are online at www.ipcc.ch.

    Should the concentration of carbon dioxide reach twice the pre-industrial average of 280 parts per million, the report said, the climate will likely warm some 3.5 to 8 degrees Fahrenheit, and there would be more than a one in 10 chance of much greater warming - a situation many earth scientists say poses an unacceptable risk.

    Many energy and environment experts see such a doubling as a foregone conclusion sometime after midcentury without a prompt and sustained shift away from the 20th-century pattern of unfettered burning of coal and oil, the main sources of carbon dioxide, and an aggressive quest for expanded and improved nonpolluting energy options.

    Even the midrange projection for warming, according to many climate experts and biologists, is likely to powerfully stress ecosystems and disrupt longstanding climate patterns that shape water supplies and agricultural production.

    "The new report powerfully underscores the need for a massive effort to slow the pace of global climatic disruption before intolerable consequences become inevitable," said John P. Holdren, the president of the American Association for the Advancement of Science and an energy and climate expert at Harvard University. "Since 2001 there has been a torrent of new scientific evidence on the magnitude, human origins and growing impacts of the climatic changes that are underway. In overwhelming proportions, this evidence has been in the direction of showing faster change, more danger and greater confidence about the dominant role of fossil fuel burning and tropical deforestation in causing the changes that are being observed."

    The conclusions came after a three-year review of hundreds of studies of clues illuminating past climate shifts, observations of retreating ice, warming and rising seas, and other shifts around the planet, and a greatly expanded suite of supercomputer simulations used to test how earth will respond to a building blanket of gases that hold heat in the atmosphere.

    Big questions remain about the speed and extent of some impending changes, both because of uncertainty about future population and pollution trends and the complex interrelationships of the greenhouse emissions, clouds, dusty kinds of pollution, the oceans and earth's veneer of life, which both emits and soaks up carbon dioxide and other such gases.

    But a broad array of scientists, including authors of the report and independent experts, said the latest analysis was the most sobering view yet of a century in which - after thousands of years of relatively stable climate conditions - the new normal is likely to be continual change.

    Should greenhouse gases continue to build in the atmosphere at even a moderate pace, temperatures by the end of the century could match those last seen 125,000 years ago, in the previous warm spell between ice ages, the report said.

    At that time, the panel said, sea levels were 12 to 20 feet higher than they are now due to the melting of great amounts of ice now stored - but eroding - on Greenland and in parts of Antarctica.

    The panel said there was no solid scientific understanding of how rapidly the vast stores of ice in polar regions will begin to erode, so their estimates for how seas will rise by 2100 - probably between 7 and 23 inches - were based mainly on how much the warmed oceans will expand, and not on contributions from melting of ice on land.

    Other scientists have recently reported evidence that the glaciers and ice sheets in the Arctic and Antarctic could flow seaward far more quickly than estimated in the past and have proposed risks to coasts could be much more imminent. But the I.P.C.C. is proscribed by its charter from entering into speculation and so could not include such possible instabilities in its assessment.

    Michel Jarraud, the secretary general of the United Nations World Meteorological Organization, said the lack of clarity should offer no one comfort. "The speed with which melting ice sheets are raising sea levels is uncertain, but the report makes clear that sea levels will rise inexorably over the coming centuries," he said. "It is a question of when and how much, and not if," he said, adding: "While the conclusions are disturbing, decision makers are now armed with the latest facts and will be better able to respond to these realities."

    Achim Steiner, the executive director of the United Nations Environment Program, which oversees the I.P.C.C. along with the meteorological group, said society now had plenty of information on which to act.

    "The implications of global warming over the coming decades for our industrial economy, water supplies, agriculture, biological diversity and even geopolitics are massive," he said. "This new report should spur policymakers to get off the fence and put strong and effective policies in place to tackle greenhouse gas emissions."

    The warming and other climate shifts will be highly variable around the world, with the Arctic particularly seeing much higher temperatures, said Susan Solomon, the co-leader of the section of the I.P.C.C. report on basic science and an atmospheric scientist for the National Oceanic and Atmospheric Administration.

    "The kinds of vulnerabilities are very much dependent on where you are," Dr. Solomon said in a telephone interview. "If you're living in parts of tropics and they're getting drier and you're a farmer there are some very acute issues associated with even small changes in rainfall. Changes we're already seeing are significant. If you are an Inuit and you're seeing your sea ice retreating already that's affecting your lifestyle and culture."

    The 20-page summary is a sketch of the findings that are most germane to the public and world leaders.

    The full I.P.C.C. report, thousands of pages of technical background, will be released in four sections through the year - the first on basic science, then sections on impacts and options for limiting emissions and limiting inevitable harms, and finally a synthesis of all of the findings near year's end.

    In a news conference in Paris, Dr. Solomon declined to provide her own views on how society should respond to the momentous changes projected in the study.

    "I honestly believe that it would be a much better service for me to keep my personal opinions separate than what I can actually offer the world as a scientist," she said. "My stepson, who is 29, has an utterly different view of risks than I do. People are going to have to make their own judgments."

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    Elisabeth Rosenthal reported from Paris, and Andrew C. Revkin from New York.

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    Warming to Drive Droughts, Flood, Storms in 21st Century, Says UN Panel
    By Richard Ingham
    Agence France-Presse

    Friday 02 February 2007

    UN scientists have delivered their starkest warning yet about global warming, saying fossil fuel pollution would raise temperatures this century, worsen floods, droughts and hurricanes and melt polar sea ice.

    The Intergovernmental Panel on Climate Change (IPCC) - the United Nations' paramount scientific authority on global warming - also dealt a crippling blow Friday to the shrinking body of opinion that claims higher temperatures have been driven by natural causes.

    It said bluntly that most of the unprecedented rise in Earth's surface temperature over the past 50 years had "very likely" been caused by human activity.

    This term means a certitude of 90 percent and signals an increase on the IPCC's previous assessment in 2001, which gave a probability of 66 percent.

    The Earth's surface temperatures will rise between 1.8 to 4.0 degrees Celsius (3.2 to 7.2 degrees Farenheit) and sea levels increase 18 to 59 centimetres (7.1 to 23.2 inches) by 2100, the IPCC's Fourth Assessment Report said. The scientists said this was their best estimate, from a broader range of possibilities derived from computer models.

    The IPCC also predicted increasingly intense storms, heatwaves and heavy rains in the decades to come.

    The impact of disgorging greenhouse gases into the atmosphere this century will cause climate disruptions "for more than a millennium" to come, it said.

    "This report is a vital piece of information," said Achim Steiner, executive director of the UN Environment Programme (UNEP).

    "It enables the world to now respond to climate change not by debating the science any more but by figuring out how on earth we are going to live in a world with an environment change scenario that is two, three, four degrees of global warming." Two to four degrees Celsius is equivalent to 3.6 to 7.2 degrees Farenheit.

    The exhaustive study, culled from work by 2,500 scientists in more than 100 countries, sounded alarms about the impact of carbon pollution, mostly from the burning of oil, gas and coal.

    These fuels release carbon dioxide (CO2), which traps heat from the sun instead of letting it radiate safely into space.

    "We are in a sense doing things have not been done in 650,000 years," IPCC Chairman Rajendra Pachauri said, referring to rising CO2 levels. "You are able to see what the costs of inaction are."

    Sea ice is predicted to shrink in both the Arctic and Antarctic, and in some projections "Arctic late summer ice disappears almost entirely by the latter part of the 21st century."

    "It is likely that that future tropical cyclones will become more intense, with large peak wind speeds and heavy precipitation," the IPCC added.

    Unseasonably warm weather, heatwaves and heavy rainstorms are "very likely" to become more frequent.

    British Environment Minister David Miliband said the report confirmed "concerns that the window of opportunity to avoid dangerous climate change is closing more quickly than previously thought".

    Miliband underlined the IPCC's increased certainty about its main conclusions as compared to its 2001 report. "The debate over the science of climate change is well and truly over," he said in a statement.

    Environmental pressure groups responded by calling for urgent international action to cut greenhouse gas emissions.

    "The IPCC report embodies an extraordinary scientific consensus that climate change is already upon us and that human activities are the cause," said WWF International director general James Leape.

    "It is a clarion call to governments to act urgently to slash emissions," he said.

    Jan Kowalzig, climate and energy campaigner for Friends of the Earth, said the document "scientifically confirms the extent of this man-made crisis already hitting people around the world and makes bleak predictions for the future".

    He added: "We can no longer afford to ignore growing and compelling warnings from the world's leading experts."

    Greenpeace climate and energy campaigner, Stephanie Tunmore, called the IPCC report a "screaming siren" of a warning.

    "The good news is our understanding of the climate system and our impact on it has improved immensely. The bad news is that the more we know, the more precarious the future looks," Tunmore said.

    Go to Original

    Warming Linked to Stronger Hurricanes
    By Seth Borenstein
    The Associated Press

    Thursday 01 February 2007

    Paris - Global warming has made stronger hurricanes, including those in the Atlantic such as Katrina, an authoritative panel on climate change has concluded for the first time, participants in the deliberations said Thursday.

    During marathon meetings in Paris, the Intergovernmental Panel on Climate Change approved language that said an increase in hurricane and tropical cyclone strength since 1970 "more likely than not" can be attributed to man-made global warming, according to Leonard Fields of Barbados and Cedric Nelom of Surinam.

    In its last report in 2001, the same panel had said there was not enough evidence to make such a conclusion.

    "It is very important" that the language is so strong this time, said Fields, whose country is on the path of many hurricanes. "Insurance companies watch the language, too."

    The panel did note that the increase in stronger storms differs in various parts of the globe, but that the storms that strike the Americas are global warming-influenced, according to another participant.

    Fields said that the report notes that most of the changes have been seen in the North Atlantic.

    The report - scheduled to be released Friday morning - is also a marked departure from a November 2006 statement by the World Meteorological Organization, which helped found the IPPC.

    The meteorological organization, after contentious debate, said it could not link past stronger storms to global warming. The debate about whether stronger hurricanes can be linked to global warming has been dividing a scientific community that is otherwise largely united in agreeing that global warming is human-made and a problem.

    Massachusetts Institute of Technology professor Kerry Emanuel, who pioneered much of the research linking global warming to an uptick in hurricane strength, looked at the original language in an IPCC draft and called it "a pretty strong statement."

    "I think we've seen a pretty clear signal in the Atlantic," Emanuel said. The increase in Atlantic hurricane strength "is so beautifully correlated with sea surface there can't be much doubt that there's a relationship with sea surface temperature."

    But U.S. National Hurricane Center scientist Christopher Landsea has long disagreed with that premise. While he would not comment on the IPCC decision, Landsea pointed to the meteorological organization's statement last fall.