Scientists urge limits on carbon dioxide emissions
By Marianne White, CanWest News Service - Canada.com, JUNE 10, 2009
QUEBEC — A group of international climate scientists, including three Canadians, is calling on governments worldwide to agree before the end of the year on limits for total carbon dioxide emissions to avoid catastrophic climate change.
The researchers sound the alarm in an open letter to the negotiators of 192 nations preparing for a new round of climate change talks to be held this December in Copenhagen.
"So far we've done hardly anything, so we need to get going on the issue and quickly," said Damon Matthews, a signatory of the letter and professor in Concordia University's Department of Geography, Planning and the Environment in Montreal.
"We need an agreement in December that results in near-term emissions reductions," he added, noting a reduction of emissions by 20 to 50 per cent within the next 20 years would be "a good start."
The scientists are drawing attention to recent studies that found a key determinant in rising global temperatures is the cumulative emission over time of greenhouse gases, most specifically carbon dioxide.
Scientists from Oxford, Chicago and Stanford universities and the Potsdam Institute for Climate Impacts Research have signed the letter. Andrew Weaver of the School of Earth and Ocean Sciences of the University of Victoria and Kirsten Zickfeld of the Canadian Centre for Climate Modelling and Analysis are the other two Canadian signatories.
Concordia's Matthews has done a study, together with colleagues from Victoria and the U.K., that shows each tonne of carbon dioxide emission will lead to 0.0000000000015 degrees of global temperature change, regardless of over what period of time the emission occurs.
The findings, to be published Thursday in Nature, will allow people to estimate their contribution to global warming based on total carbon dioxide emissions.
There is consensus among scientists that the Earth's temperature should not rise by more than two degrees Celsius. An increase above that level would lead to widespread destruction of ecosystems and an irreversible melting of the polar ice caps.
In order to restrict global warming to no more than two degrees, Matthews said the planet must forever restrict total carbon emissions to only as much as what has already been emitted, or half a trillion tonnes of carbon.
"If we keep going on the track we're going today, we'll use up the allowable emissions budget within a couple of decades," he said.
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