Climate Could Cross Critical Threshold by 2100, Expert Warns 02.16.09  

New studies reveal potentially dangerous feedbacks in the climate system that could convert current carbon sinks into carbon sources



Without decisive action by governments, corporations and individuals, global warming in the 21st century is likely to accelerate at a much faster pace and cause more environmental damage than predicted, warns a leading member of the Nobel Prize-winning Intergovernmental Panel on Climate Change.

Chris Field, a member of the Intergovernmental Panel on Climate Change (IPCC), says predicted global temperature rises of between 1.1C and 6.4C in the group's 2007 report had been underestimated.

"We are basically looking now at a future climate that is beyond anything that we've considered seriously in climate policy," he told a meeting of the the American Association for the Advancement of Science in Chicago on Saturday. The IPCC's 2007 report had warned of rising sea levels, expanding deserts, more intense storms and the extinction of up to 30 per cent of plant and animal species.

'Too optimistic'

Field, however, said that report had failed to take into account new coal-fired power stations in developing countries like China and India, and the huge increase in carbon emissions they would create. "Without aggressive attention, societies will continue to focus on the energy sources that are cheapest, and that means coal." Predictions of a decrease in carbon emissions had also been too optimistic, he said, as no part of the world has seen such a decline between 2000 and 2008.

Bolstering Field's arguments, Anny Cazenave of France's National Centre for Space Studies, told the meeting that new satellite measurements show that sea levels are rising at an increased rate, due to warming waters and melting ice sheets.

Field further said that there was a "real risk that human-caused climate change will accelerate the release of carbon dioxide from forest and tundra ecosystems, which have been storing a lot of carbon for thousands of years." That could raise temperatures even more and create "a vicious cycle that could spiral out of control by the end of the century," he said.

Several recent climate models have estimated that the loss of tropical rainforests to wildfires, deforestation and other causes could increase the concentration of carbon dioxide in the atmosphere from 10 to 100 parts per million by the end of the 21st century.

In a business-as-usual world, higher temperatures could ignite tropical forests and melt the Arctic tundra, releasing billions of tons of greenhouse gas that could raise global temperatures even more - a vicious cycle that could spiral out of control by the end of the century, said IPCC scientist Chris Field of Stanford University and the Carnegie Institution for Science. (...)

This is a crucial year in the international effort to address climate change. Intergovernmental negotiations will be taking place all year, culminating in the United Nations Climate Change Conference in Copenhagen, December 7-18. There, governments are expected to finalize a treaty to limit greenhouse gas emissions that will take effect when the current Kyoto Protocol expires at the end of 2012.

In their negotiations, governments rely on the facts presented in the assessment reports published by the IPCC. Established by the United Nations in 1988, the IPCC brings together thousands of experts from around the world to assess the science and policy implications of climate change. The IPCC does not conduct any research nor does it monitor climate related data or parameters. Its role is to assess on a comprehensive, objective, open and transparent basis the latest scientific, technical and socio-economic literature produced worldwide concerning the risk of human-induced climate change, its observed and projected impacts and options for adaptation and mitigation.

In 2007, the IPCC and Al Gore were awarded the Nobel Peace Prize. Field was among 25 IPCC scientists who attended the award ceremony in Oslo, Norway. In September 2008, Field was elected co-chair of Working Group 2, which is charged with assessing the impacts of climate change on social, economic and natural systems. One of his major responsibilities is to oversee the writing and editing of the "Working Group 2 Report" for the IPCC fifth assessment, slated for publication in 2014. (...)

New studies are revealing potentially dangerous feedbacks in the climate system that could convert current carbon sinks into carbon sources. Field points to tropical forests as a prime example. Vast amounts of carbon are stored in the vegetation of moist tropical forests, which are resistant to wildfires because of their wetness. But warming temperatures and shifting rainfall patterns threaten to dry the forests, making them less fireproof. Researchers estimate that loss of forests through wildfires and other causes during the next century could boost atmospheric concentration of the greenhouse gas carbon dioxide by up to 100 parts per million over the current 386 ppm, with possibly devastating consequences for global climate.

Warming in the Arctic is expected to speed up the decay of plant matter that has been in cold storage in permafrost for thousands of years. "There is about 1,000 billion tons of carbon in these soils," says Field. "When you consider that the total amount of carbon released from fossil fuels since the beginning of the Industrial Revolution is around 350 billion tons, the implications for global climate are staggering."

"One thing that seems to be certain," he said, "is that as a society we are facing a climate crisis that is larger and harder to deal with than any of us thought. The sooner we take decisive action, the better our chances are of leaving a sustainable world to future generations."


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