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Rising carbon emissions alarm scientists
Report shows climate changing even faster than expected
Margaret Munro,
The Ottawa Citizen
Published: Tuesday, October 23, 2007
Earth's atmosphere is accumulating carbon dioxide much faster than expected, says an international team tracking changes in the global climate system.
Not only are humans pumping greenhouse gases into the air at an unprecedented rate, but the planet's "carbon sinks" are not absorbing as much CO2 as they used to, the team reported yesterday in the Proceedings of the National Academy of Sciences.
They report major droughts in the mid-latitudes between 2002 and 2005 have led to "weakening" of terrestrial carbon sinks -- the growth of trees, shrubs and crops that take CO2 from the air. And changes in wind patterns have enhanced the "ventilation of carbon-rich waters" in the southern oceans since 2000. Add it all up, the scientists say, and the growth rate of atmospheric CO2 is "increasing rapidly.
The rise in emissions, while very worrying to scientists, is not unexpected given the economic boom in India and China, which is maintained largely by the burning of coal and other fossil fuels. More surprising is the decline in the efficiency of the natural carbon sinks, says climatologist Josep Canadell, lead author of the report and executive director of the Global Carbon Project.
"We are showing it is already happening," Mr. Canadell said in a phone interview from his office in Australia.
Canadian climate scientist Ken Denman said the report is "important" and adds to mounting evidence the climate system is changing faster than expected.
"We have to be concerned," said Mr. Denman, a senior scientist with the federal Department of Fisheries and Oceans and a lead author of the Intergovernmental Panel on Climate Change, the UN body that has been assessing the dangers. The panel recently won the Nobel Peace Prize."If the trends of the last few years continue, everything is going to happen faster than we thought based on our model projections," he said, adding that the trends are "not good."Mr. Canadell said the new data indicate the climate is following the worst-case scenarios and underscores the need to reduce emissions as soon as possible.
"The longer we wait to do the emission cuts, the harder it will be to stabilize CO2 in the atmosphere," he said.Between 2000 and 2006, total human emissions grew an at annual rate of almost three per cent -- or four times faster than in the preceding 10 years, Mr. Canadell and his colleagues reported.
There are calls for governments to commit to major cuts to emissions by 2050 in a bid to avoid going beyond an atmospheric CO2 concentration of 450 parts per million -- a threshold many scientists fear could trigger mass extinctions, and the eventual melting of the Greenland ice sheet and a seven-metre rise in the sea level.
The concentration is now at 382 ppm "which means we have 68 ppm to go to 450 ppm," said Mr. Canadell. The concentration is now rising at about two ppm per year, so the threshold could be crossed in less than 35 years if emissions are not cut.
Yesterday's report said close to 10 billion tonnes of carbon dioxide, one of the main drivers of climate change, now waft into the air each year from human activities such as burning coal, oil and gas and deforestation.
The atmospheric CO2 concentration "is the highest during the past 650,000 years and probably during the last 20 million years," the report said.
The report is based on data from the United Nations and the U.S. National Oceanic and Atmospheric Administration. It concludes the changes under way "characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing."
Government officials from around the world are to meet in December to discuss emission reductions.
© The Ottawa Citizen 2007
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