Natural latitudinal distribution of atmospheric CO2.

[摘要] Although poorly understood, the north-south distribution of the natural component of atmospheric CO2 offers information essential to improving our understanding of the exchange of CO2 between the atmosphere, oceans, and biosphere. The natural or unperturbed component is equivalent to that part of the atmospheric CO2 distribution, which is controlled by non-anthropogenic CO2 fluxes from the ocean and terrestrial biosphere. Models should be able to reproduce the true north-south gradient in CO2 due to the natural component before they can reliably estimate present-day CO2 sources and sinks and predict future atmospheric CO2. We have estimated the natural latitudinal distribution of atmospheric CO2, relative to the South Pole, using measurements of atmospheric CO2 during 1959-1991 and corresponding estimates of anthropogenic CO2 emissions to the atmosphere. Key features of the natural latitudinal distribution include (1) CO2 concentrations in the Northern Hemisphere that were lower than those in the Southern Hemisphere, (2) CO2 concentration differences that are higher in the tropics (associated with outgassing of the oceans) than those currently measured, and (3) CO2 concentrations over the Southern Ocean that are relatively uniform. This natural latitudinal distribution and its sensitivity to increasing fossil fuel emissions indicate that near-surface concentrations of atmospheric CO2 in the Northern Hemisphere are naturally lower than those in the southern hemisphere. Models that find the contrary will also mismatch present-day CO2 in the northern hemisphere and incorrectly ascribe that region as a large sink of anthropogenic CO2.

[发布机构] Technical Information Center Oak Ridge Tennessee

[学科分类] 工程和技术（综合）

[关键词] Carbon dioxide;Ecological concentration;Latitude effect;Spatial distribution;Exchanges