Climate Could Cross Critical Threshold by 2100, Expert Warns

Climate Could Cross Critical Threshold by 2100,
Expert Warns

Environment News Service 16feb2009

CHICAGO, Illinois — 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.
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.
Field presented his findings Saturday at the annual meeting of the American Association for the Advancement of Science in Chicago during a symposium titled, "What Is New and Surprising Since the IPCC Fourth Assessment?"
The IPCC Fourth Assessment, for which Field was a coordinating author, was published in 2007.
"There is 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," said Field, a professor of biology and of environmental Earth system science at Stanford, and a senior fellow at Stanford's Woods Institute for the Environment.
"We don't want to cross a critical threshold where this massive release of carbon starts to run on autopilot," he said.
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.
The fifth assessment will incorporate the results of new studies that predict more severe changes than did previous assessments.
"The IPCC fourth assessment didn't consider either the tundra-thawing or tropical forest feedbacks in detail because they weren't yet well understood," he says. "But new studies are now available, so we should be able to assess a wider range of factors and possible climate outcomes."
"The data now show that greenhouse gas emissions are accelerating much faster than we thought," said Field. "Over the last decade developing countries such as China and India have increased their electric power generation by burning more coal. Economies in the developing world are becoming more, not less carbon-intensive. We are definitely in unexplored terrain with the trajectory of climate change, in the region with forcing, and very likely impacts, much worse than predicted in the fourth assessment."
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."
Field is founding director of the Department of Global Ecology at the Carnegie Institution for Science, a private organization that conducts basic research for the benefit of humanity.
The author of more than 200 scientific publications, Field's research emphasizes impacts of climate change, from the molecular to the global scale. His work includes major field experiments on responses of California grassland to multi-factor global change, integrative studies on the global carbon cycle, and assessments of impacts of climate change on agriculture.
Late last year, Field was elected an AAAS Fellow by the American Association for the Advancement of Science. The AAAS said Field was elected "for his central role in developing global ecology, with major contributions to the global carbon cycle, climate-change impacts, and feedbacks of ecosystems to climate change."

source: 19feb2009