Randolph E. Schmid, Associated Press 27 Jan 09;
WASHINGTON – Many damaging effects of climate change are already basically irreversible, researchers declared Monday, warning that even if carbon emissions can somehow be halted temperatures around the globe will remain high until at least the year 3000.
"People have imagined that if we stopped emitting carbon dioxide the climate would go back to normal in 100 years, 200 years; that's not true," climate researcher Susan Solomon said in a teleconference.
Solomon, of the National Oceanic and Atmospheric Administration's Earth System Research Laboratory in Boulder, Colo., is lead author of an international team's paper reporting irreversible damage from climate change, being published in Tuesday's edition of Proceedings of the National Academy of Sciences.
She defines "irreversible" as change that would remain for 1,000 years even if humans stopped adding carbon to the atmosphere immediately.
The findings were announced as President Barack Obama ordered reviews that could lead to greater fuel efficiency and cleaner air, saying the Earth's future depends on cutting air pollution.
Said Solomon, "Climate change is slow, but it is unstoppable" — all the more reason to act quickly, so the long-term situation doesn't get even worse.
Alan Robock, of the Center for Environmental Prediction at Rutgers University, agreed with the report's assessment.
"It's not like air pollution where if we turn off a smokestack, in a few days the air is clear," said Robock, who was not part of Solomon's research team. "It means we have to try even harder to reduce emissions," he said in a telephone interview.
Solomon's report "is quite important, not alarmist, and very important for the current debates on climate policy," added Jonathan Overpeck, a climate researcher at the University of Arizona.
In her paper Solomon, a leader of the International Panel on Climate Change and one of the world's best known researchers on the subject, noted that temperatures around the globe have risen and changes in rainfall patterns have been observed in areas around the Mediterranean, southern Africa and southwestern North America.
Warmer climate also is causing expansion of the ocean, and that is expected to increase with the melting of ice on Greenland and Antarctica, the researchers said.
"I don't think that the very long time scale of the persistence of these effects has been understood," Solomon said.
Global warming has been slowed by the ocean, Solomon said, because water absorbs a lot of energy to warm up. But that good effect will not only wane over time, the ocean will help keep the planet warmer by giving off its accumulated heat to the air.
Climate change has been driven by gases in the atmosphere that trap heat from solar radiation and raise the planet's temperature — the "greenhouse effect." Carbon dioxide has been the most important of those gases because it remains in the air for hundreds of years. While other gases are responsible for nearly half of the warming, they degrade more rapidly, Solomon said.
Before the industrial revolution the air contained about 280 parts per million of carbon dioxide. That has risen to 385 ppm today, and politicians and scientists have debated at what level it could be stabilized.
Solomon's paper concludes that if CO2 is allowed to peak at 450-600 parts per million, the results would include persistent decreases in dry-season rainfall that are comparable to the 1930s North American Dust Bowl in zones including southern Europe, northern Africa, southwestern North America, southern Africa and western Australia.
Gerald Meehl, a senior scientist at the National Center for Atmospheric Research, said, "The real concern is that the longer we wait to do something, the higher the level of irreversible climate change to which we'll have to adapt." Meehl was not part of Solomon's research team.
While scientists have been aware of the long-term aspects of climate change, the new report highlights and provides more specifics on them, said Kevin Trenberth, head of climate analysis at the center.
"This aspect is one that is poorly appreciated by policymakers and the general public and it is real," said Trenberth, who was not part of the research group.
"The temperature changes and the sea level changes are, if anything underestimated and quite conservative, especially for sea level," he said.
While he agreed that the rainfall changes mentioned in the paper are under way, Trenberth disagreed with some details of that part of the report.
"Even so, there would be changes in snow (to rain), snow pack and water resources, and irreversible consequences even if not quite the way the authors describe," he said. "The policy relevance is clear: We need to act sooner ... because by the time the public and policymakers really realize the changes are here it is far too late to do anything about it. In fact, as the authors point out, it is already too late for some effects."
Co-authors of the paper were Gian-Kaspar Plattner and Reto Knutti of the Swiss Federal Institute of Technology in Zurich and Pierre Friedlingstein of the National Institute for Scientific Research, Gif sur Yvette, France.
The research was supported by the Office of Science at the Department of Energy.
Fast Action Needed To Avoid Climate Chaos: Study
Pete Harrison, PlanetArk 27 Jan 09;
BRUSSELS - Global temperature rises due to climate change could be kept below the critical 2 degree mark by fast international action to cut greenhouse gas emissions by 70 percent by 2030, a report said on Monday.
Scientists say that if temperatures increase beyond 2 degrees, humanity faces severe environmental fallout, such as melting polar ice caps and rising sealevels.
Increasing numbers of scientists and politicians question whether the 2 degrees goal is achievable, given the slow progress of international negotiations so far.
But it is not too late to avert dangerous climate change, said the report by consultancy McKinsey and backed by ten organizations including energy companies, Enel, Vattenfall and Royal Dutch Shell.
"Achieving the deep emissions cuts required to keep global warming below the 2 degrees limit is possible but difficult," said McKinsey director Tomas Naucler.
Global investment of 530 billion euros ($686 billion) would be needed by 2020, and 810 billion by 2030, the report added.
Countries would offset much of the cost by simultaneously cutting their bills for oil, gas and coal, resulting in a net cost of less than 1 percent of gross domestic product.
The report comes one month after the European Union agreed ambitious measures to cut carbon dioxide and amid renewed optimism U.S. President Barack Obama will lend fresh momentum to global talks after having pledged to curb emissions at home.
Obama will start reversing former President George W. Bush's climate policies on Monday with steps to raise fuel efficiency standards and to grant states authority to limit emissions from cars, officials say.
Keeping climate change manageable would require fast global action, said the report.
A 70 percent cut in emissions by 2030 would see greenhouse gas emissions peaking at 480 parts per million (ppm), roughly the level scientists say would cause a 2 degree rise.
But a 10-year delay would make it difficult to keep greenhouse gas emissions below 550 parts per million (ppm).
"Every year of delay adds to the challenge, not only because emissions will continue to grow during that year, but also because it will lock the economy into high-carbon infrastructure," said the report.
Long Droughts, Rising Seas Predicted Despite Future CO2 Curbs
Juliet Eilperin, Washington Post 27 Jan 09;
Greenhouse gas levels currently expected by mid-century will produce devastating long-term droughts and a sea-level rise that will persist for 1,000 years regardless of how well the world curbs future emissions of carbon dioxide, an international team of scientists reported yesterday.
Top climate researchers from the U.S. National Oceanic and Atmospheric Administration, Switzerland and France said their analysis shows that carbon dioxide will remain near peak levels in the atmosphere far longer than other greenhouse gases, which dissipate relatively quickly.
"I think you have to think about this stuff as more like nuclear waste than acid rain: The more we add, the worse off we'll be," NOAA senior scientist Susan Solomon told reporters in a conference call. "The more time that we take to make decisions about carbon dioxide, the more irreversible climate change we'll be locked into."
At the moment, carbon concentrations in the atmosphere stand at 385 parts per million. Many climate scientists and the United Nations' Intergovernmental Panel on Climate Change have set a goal of stabilizing atmospheric carbon at 450 ppm, but current projections put the world on track to hit 550 ppm by 2035, rising after that point by 4.5 percent a year.
The new study, published in the Proceedings of the National Academy of Sciences, projects that if carbon dioxide concentrations peak at 600 ppm, several regions of the world -- including southwestern North America, the Mediterranean and southern Africa -- will face major droughts as bad or worse than the Dust Bowl of the 1930s. Global sea levels will rise by roughly three feet by the year 3000, a projection that does not factor in melting glaciers and polar ice sheets that would probably result in significant additional sea level rises.
Even if the world managed to halt the carbon dioxide buildup at 450 ppm, the researchers concluded, the subtropics would experience a 10 percent decrease in precipitation, compared with the 15 percent decrease they would see at 600 ppm. That level is still akin to mega-droughts such as the Dust Bowl. The already parched U.S. Southwest would probably see a 5 percent drop in precipitation during its dry season.
Mary-Elena Carr, associate director of the Columbia Climate Center, called the new projections "very sobering." She noted that while societies can try to adapt to reduced precipitation with better farming techniques and other measures, there is a limit to the ability to cope with severe drought.
"When it's drought, that is hard, because we have a finite amount of water and a growing population we need to feed," Carr said, adding the severe storm surges associated with higher sea levels also pose a dangerous challenge to large populations.
The rising sea levels anticipated under a conservative projection, the authors wrote, would cause "irreversible commitments to future changes in the geography of the Earth, since many coastal and island features would ultimately become submerged."
The scientists noted that the world's oceans are already absorbing an enormous amount of carbon, but over time this will reach a limit and they will no longer absorb as much. As this happens, the atmospheric temperature will remain nearly constant.
Most previous scientific analyses, including the U.N. panel's summary report for policymakers, have assessed climate change impacts on a 100-year time scale. A few researchers, such as Ken Caldeira of the Carnegie Institution's Department of Global Ecology, have argued that it makes more sense to look at a time scale of at least 500 years.
In an e-mail yesterday, Caldeira wrote that he had debated this point with other contributors to the U.N. reports in 2001, adding, "If you took our long term climate commitment seriously, you would not use 100-year [global warming projections] to compare effects of different gases."
Carbon dioxide emissions account only for roughly half of human-induced global warming, but the several other gases that play a role, including methane, dissipate more quickly. Solomon said policymakers could take this into account when deciding how best to reduce greenhouse gases overall.
"We ought to be extra careful about how much carbon dioxide we put out in the future," she said, adding that politicians often focus on the less certain but potentially disastrous impacts of climate change but would do well to focus on the more predictable consequences. "The parts that we don't know, that are possible but very uncertain, shouldn't get in the way of what we do know."
A separate study in the same journal yesterday suggests that the iconic emperor penguins of the Antarctic could be headed to extinction by 2100 if the sea ice shrinks by the predicted amounts. That paper -- authored by scientists from the Woods Hole Oceanographic Institution, National Center for Atmospheric Research, the National Snow and Ice Data Center in Boulder and France's Centre National de la Recherche Scientifique -- projects that the number of breeding pairs in a colony in Terre Adelie, Antarctica, will decline from roughly 6,000 to 400 by the end of the century because the animals depend on sea ice for breeding, foraging and molting habitat.
Emperor penguins would have to migrate or change the timing of their growth stages to avoid extinction, the authors write, but "evolution or migration seem unlikely for such long-lived species at the remote southern end of the Earth."
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