Carbon dioxide emissions from fossil fuels up by 29 per cent since 2000 - 18 November 2009
Carbon dioxide emissions from the burning of fossil fuels are increasing
Scientists have produced the strongest evidence yet that the rise in atmospheric carbon dioxide (CO2) emissions continues to outstrip the ability of the world's natural carbon sinks to absorb carbon.
An international team of scientists under the umbrella of the Global Carbon Project reports that over the last 50 years the average fraction of global CO2 emissions remaining in the atmosphere has likely increased. The scientists also report a 29 per cent increase in global CO2 emissions from fossil fuel between 2000 and 2008, with emissions increasing by 2 per cent during 2008, the latest year for which figures are available.
One of those involved in the project is Dr Chris Huntingford, a climate modeller with the Centre for Ecology & Hydrology (CEH). He said the analysis demonstrated that both the land surface and oceans remained strong natural sinks, but there were concerns that combined computer climate-carbon cycle simulations, as presented in other pieces of research, implied that the efficiency of such sinks will diminish.
"This reduction could be significant, affecting the size of future emissions reductions required to achieve climate stabilisation. There remain many challenges for the UK research community in constraining more tightly parameters in such future climate-carbon cycle simulations."
"There remains concern that combined computer climate-carbon cycle simulations imply that the efficiency of natural sinks will diminish."
Chris Huntingford, Centre for Ecology & Hydrology
The scientists' findings have been published in the journal Nature Geoscience. According to the study the average fraction of global CO2 emissions remaining in the atmosphere each year over the last 50 years was around 43 per cent - the rest was absorbed by the Earth's carbon sinks on land and in the oceans. During this time this fraction has likely increased from 40 per cent to 45 per cent. The team's findings suggest the sinks are responding to climate change and variability.
The scientists report that coal as a fossil fuel emission source has now surpassed that of oil and that developing countries are now emitting more greenhouse gases than developed countries - but a quarter of this growth in emissions is actually accounted for by increased trade in goods and services with developed countries.
There is still uncertainty, however, about the behaviour of the world's carbon sinks. The report's lead author Professor Corinne Le Quéré, of the University of East Anglia and the British Antarctic Survey, explained, "The Earth's carbon sinks are complex and there are some gaps in our understanding, particularly in our ability to link human-induced CO2 emissions to atmospheric CO2 concentrations on a year-to-year basis. But, if we can reduce the uncertainty about the carbon sinks, our data could be used to verify the effectiveness of climate mitigation policies."
She said the only way to control climate change was through a drastic reduction in global CO2 emissions.
The researchers called for more work to be done to improve understanding of the land and ocean CO2 sinks, so that global action to control climate change could be monitored independently. The sinks have a major influence on climate change and are important in understanding the link between CO2 emissions caused by humans and atmospheric CO2 concentration.
So far scientists have not been able to calculate the CO2 uptake of the sinks with sufficient accuracy to explain all the annual changes in atmospheric CO2 concentration, thus hindering their ability to monitor the effectiveness of CO2 mitigation policies.
Additional information
'Trends in the sources and sinks of carbon dioxide' is published in Nature Geoscience. Among the more than 30-strong team making up the Global Carbon Project are two scientists from the Centre for Ecology & Hydrology, Chris Huntingford and Peter Levy.
Many of the observations and modelling analyses were supported by funding agencies in the European Union (CARBOOCEAN and the Natural Environment Research Council’s QUEST programme), the United States (the National Science Foundation, NASA, the National Oceanic and Atmospheric Administration and the Office of Science of the Department of Energy), Australia and Brazil.
Related CEH links and news stories
Details of CEH's science programmes
Dr Chris Huntingford's staff page
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