The Earth’s ecosystems and oceans might have a much greater capacity for absorbing carbon dioxide than has previously been thought, according to new research from the University of Bristol.

That finding runs contrary to a significant body of science that predicts the planet’s ability to take up carbon dioxide will diminish as emissions keep rising.

Wolfgang Knorr says he’s found that the balance between the airborne and the absorbed fraction of carbon dioxide has stayed approximately constant since 1850, despite emissions of carbon dioxide having risen from about 2 billion tonnes a year in 1850 to 35 billion tonnes a year now.

Knorr’s study, published online in the journal Geophysical Research Letters, is based solely on measurements and statistical data, including historical records extracted from Antarctic ice, rather than on computations with complex climate models.

His findings have implications for future climate change policies, because emission targets to be negotiated at the United Nations Climate Change Conference in Copenhagen early next month have been based on projections that have a carbon-free sink already factored in. Some researchers have cautioned against this approach, pointing at evidence that suggests the sink has already started to decrease.

However, Knorr cautioned that his study is not necessarily cause for optimism.

“Like all studies of this kind, there are uncertainties in the data, so rather than relying on nature to provide a free service, soaking up our waste carbon, we need to ascertain why the proportion being absorbed has not changed,” he said.

Knorr’s study also found that emissions from deforestation might have been overestimated by between 18 and 75 per cent. This would agree with results published last week in Nature Geoscience, which concluded that emissions have been overestimated by at least a factor of two.

Tags: carbon sinks