On the Increased Rate of Atmospheric Carbon Dioxide Accumulation 1980–2008

An attempt was made to statistically explain the yearly increased rate of atmospheric carbon dioxide accumulation by means of the yearly emissions of anthropogenic carbon dioxide and the global mean temperature using data from the period 1980–2007. It is commonly assumed (e.g. by the UN Intergovernmental Panel on Climate Change; IPCC) that a part of the emitted carbon dioxide will stay in the atmosphere and, therefore, large emission rate of carbon dioxide should cause large increase rate of atmospheric carbon dioxide. High temperature should also increase the atmospheric carbon dioxide concentration due to lowered solubility of carbon dioxide in the backmixed ocean surface water. However, using two-dimensional regression analysis, the increase rate could not be explained by the emissions because temperature was the dominating parameter that controlled the increase rate. The fraction of the emissions that remained in the atmosphere—or the airborne fraction—decreased significantly despite global warming. This may be explained by increased diffusion or sink flow to the biosphere and the oceans due to increased atmospheric partial pressure of carbon dioxide.