New data shows 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 2bn tons a year in 1850 to the current 35bn tons a year.
This suggests that terrestrial ecosystems and the oceans have a much greater capacity to absorb CO2 than had been previously expected.
The results run contrary to a significant body of recent research that expects the capacity of terrestrial ecosystems and the oceans to absorb CO2 to start to diminish as CO2 emissions increase, letting greenhouse gas levels skyrocket.
Dr Wolfgang Knorr at Bristol University found that in fact the trend in the airborne fraction since 1850 has only been 0.7 ± 1.4 per cent per decade.
The strength of the new study, published online in Geophysical Research Letters, is that it rests solely on measurements and statistical data, including historical records extracted from Antarctic ice, and does not rely on computations with complex climate models.
‘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,’ said Knorr.