[From the USA Today:]
Prominent U.S. scientists and others said Friday that a new international climate report's dire outlook for global warming this century demands action but is not an impossible challenge.
The report by the Intergovernmental Panel on Climate Change (IPCC) foresees a steady rise in temperatures and sea levels for centuries because of human-caused global warming [summary for policy makers here].
"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widspread melting of snow and ice, and rising ... sea level," said the panel, a joint, 193-nation effort of the United Nations and the world Meteorological Organization.
A 21-page summary of the report said global warming is "very likely" caused mostly by human activity ['very likely' meaning with >90% certainty in the report] — in particular carbon dioxide emissions from the burning of fossil fuels — and not merely natural processes of Earth and its atmosphere. The panel said warming will "continue for centuries" regardless of how much the world reduces "greenhouse" emissions.
"We can adapt our way through this," said Jonathan Overpeck, a University of Arizona climate scientist who helped draft the summary and coordinated a chapter in the report. "What the IPCC is endeavoring to do is show everybody what's going to happen if we just let it go unabated, if we pull back some, or if we really try to cut emissions. It's just like turning the dial up. We control this climate system, that's clear. We can turn the dial down or keep it up."
Gerald Meehl, a senior scientist at the Colorado-based National Center for Atmospheric Research (NCAR) and lead author of the report's chapter on projections of future climate change, added: "The longer you wait, the worse the problem gets. The longer you wait, the longer it takes (to fix)."
The panel's bleak summary, released Friday in Paris, lays out the how, what and why of global warming, but not remedies to the problem. Two more reports by the panel this spring will address in detail the effects of climate change and the most promising measures for slowing global warming.
"We are on the historic threshold of the irreversible," warned French President Jacques Chirac, who called for an economic and political "revolution" to save the planet.
Achim Steiner, head of the U.N. Environment Program, said the report is a call to action and that the people of the world "should not sit back and say, 'There's nothing we can do.' Anyone who would continue to risk inaction on the basis of the evidence presented here will one day in the history books be considered irresponsible."
The report said human-caused emissions of greenhouse gases can already be blamed for fewer cold days, hotter nights, killer heat waves, floods and heavy rains, devastating droughts, and an increase in the strength and rainfall in hurricanes and tropical storms, particularly in the Atlantic Ocean. Americans among the more than 1,600 scientists who participated in the report said all those elements are projected to grow worse in the USA, too.
[Image: summary of observed climate trends and level of certainty regarding human cause. Source: IPCC Summary for Policy Makers. Virtually certain > 99% probability of occurrence, Very likely > 90%, Likely > 66%, More likely than not > 50%. (Click to Enlarge)]
"The element of surprise here is that the picture is becoming so clear that (climate) changes are due to human activity," said Ralph Cicerone, president of the National Academy of Sciences. "And the warming really is everywhere. We're not seeing pockets of cooling anymore."
Despite the report's strong wording, the Bush administration opposes a mandatory "cap" on the heat-trapping "greenhouse" gases primarily responsible for Earth's warm-up. Energy Secretary Samuel Bodman said "unintended consequences" could result, including job losses to countries without limits on carbon dioxide emissions from the burning of fossil fuels. "We need a global solution," Bodman said. The administration's strategy emphasizes "market forces. .. (and) solutions that are technically and economically sound."
Linda Mearns, who heads NCAR's Institute for the Study of Society and the Environment, said ordinary citizens and local and regional politicians already are leading the response to climate change in the USA, which produces about one-quarter of the world's carbon dioxide emissions.
"Since we haven't had a lot of clear leadership at the top, it has actually created opportunity for more grassroots efforts," said Mearns, one of the report's lead authors on regional climate projections. She called it "truly extraordinary" that more than 375 U.S. mayors, representing one-third of the nation's population, have signed a pact pledging to cut greenhouse gases in their communities.
In Washington, Democrats seized on the report to criticize the administration.
"Although President Bush just noticed that the earth is heating up, the American public, every reputable scientist and other world leaders have long recognized that global warming is real and it's serious. The time to act is now," said Sen. John Kerry, D-Mass. He and Sen. Olympia Snowe, R-Maine, have sponsored one of a number of bills to tackle global warming.
But the White House defended Bush's record, saying he acknowledged in 2001 that rising greenhouse gases are due largely to humans. It said Bush has budgeted or proposed $29 billion for climate change science, technology, international aid and incentives, "more money than any other country."
Myron Ebell, global warming policy chief at the Competitive Enterprise Institute, a conservative think tank in Washington, said the report is "less alarmist" than the last assessment in 2001. But he said the "hoopla saying that the further along we go, the more alarmed we should be is not justified by the report."
Mark Bernstein, a professor at the University of Southern California, said it took a long time for the public to accept the link between cancer and cigarettes. He believes the climate report will move more people toward the same kind of acceptance of the connection of human activities to climate change.
The report is blunt. If things look bad now, the harmful effects of warming the rest of this century will "very likely be larger than those observed during the 20th century," it says. It predicts temperature rises of 2°F to 11.5°F by the year 2100, a wider range than in the last report in 2001. The panel said its best estimate, however, is for rises of 3.2°F to 7.1°F.
On sea levels, the report projects rises of 7 to 23 inches by the end of this century. An additional 3.9 to 7.8 inches are possible if recent, surprising melting of polar ice sheets continues. Some scientists dispute that as too conservative and believe the rise will be in feet, not inches, if melting in Greenland and Antarctic worsens. Meehl from NCAR warned that continued global warming could eventually lead to an "ice-free Arctic."
[Image: The IPCC report concluded that there was not yet enough solid scientific understanding of how rapidly the vast stores of ice in Greenland and other polar regions will begin to erode. The effect of Greenland ice melt was thus not included in this consensus report's estimates of sea temperature increases which were confined to melting glaciers and the thermal expansion of the world's oceans. Sea level rises could be measured in feet instead of inches if melting worsens in Greenland and Antarctica.]
As for hurricanes, Tom Karl, director of NOAA's National Climatic Data Center said that the report shows "some evidence that there has been an increase in intensity in tropical storms and hurricanes. While there won't necessarily be more storms, it's likely that the most intense storms will become more intense, and that an increase in precipitation and wind speeds are likely. But there's still a fair bit of uncertainty in the data – this remains a cutting edge research topic."
Adapting to climate change is the next hurdle for the world, said Vicky Pope, climate program chief at Great Britain's Hadley Center, which does climate research for the United Kingdom. Drought and heat waves will be a principal concern in many regions.
Although Pope was not directly involved in the IPCC work, her center did a study last October — too late to be included in the panel report — showing droughts were more frequent in the past 50 years and will be more so in the next century. In addition, she said moderate droughts, "something that happens to us 25% of the time," will double in frequency, and extreme drought will jump from 3% of the time now to 30% of the time.
Joseph Romm, a senior fellow at the Center for American Progress, a Washington think tank, said the "sleeper issue" in the panel report is "carbon feedback," or the possibility that Earth's biosphere — the air, ground, vegetation and seas — will reach a saturation point for carbon dioxide emissions.
"Right now, about 40% of carbon dioxide emissions get taken up by those various 'sinks,' " said Romm, author of Hell and High Water: Global Warming, The Solution and the Politics. If the biosphere maxes out and starts releasing that carbon, "that's the point of no return." Of particular worry, he said, is the frozen tundra of northern latitudes, which holds vast amounts of carbon that would release if polar warming worsens.
As the IPCC report was being released, environmental activists rappeled off a Paris bridge and draped a banner over a statue used often as a popular gauge of whether the Seine River is running high.
"Alarm bells are ringing," said Catherine Pearce of Friends of the Earth, an environmental group. "The world must wake up to the threat posed by climate change."
I'd like to point out that the IPCC report is a consensus document. It represents the work of over 2,500 scientific expert reviewers, more than 800 contributing authors and 450+ lead authors representing 193 countries. The report took six years to repare and represents the opinions of the best minds in the world on the current understanding of climate change science.
The Summary for Policy Makers in particular is a true consensus document in which not a single line could be printed without approval from representatives of more than 100 active reviewing memeber-nations in the IPCC, including ample representation of the United States government. Every sentance in the summary was belabored over for weeks before the summary's release to the public today.
This summary document should be considered a clear and practically unimpeachable representation of the worldwide scientific consensus on climate change, and the unerlying full report is a veritable treasure trove of imformation on the state of climate science today representing reviews of every peer-reviewed article on the topic published since the last IPCC report in 2001.
We may belabor exactly how much sea levels will rise, or how much global temperatures will increase; we may not know with certainty that hurricanes are increasing in intensity because of warming sea and air temperatures; in short, we can debate about the particular consequense of climate, but as the IPCC report now makes clear, it is simply "uniquivocal" that the climate IS warming, and we can say with greater than 90% certainty that human-produced greenhouse gas emissions are to blame.
It is now high time to leave behind the weary debate about the science of climate change and begin to discuss in ernest policy options and then implement as quickly as practicably possible smart solutions to the climate challenge.
We clearly know enough now to see that the risks of continued inaction are simply to high.
Other articles today on the IPCC 4th Assessment Report:
Friday, February 02, 2007
Climate Report's Outlook Dire, but Challenge is Not Insurmountable
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