Atmospheric Carbon Dioxide and Carbon Reservoir Changes

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Science  20 Jan 1978:
Vol. 199, Issue 4326, pp. 253-258
DOI: 10.1126/science.199.4326.253


The net release of CO2 from the biosphere to the atmosphere between 1850 and 1950 is estimated to amount to 1.2 x 109 tons of carbon per year. During this interval, changes in land use reduced the total terrestrial biomass by 7 percent. There has been a smaller reduction in biomass over the last few decades. In the middle 19th century the air had a CO2 content of approximately 268 parts per millon, and the total increase in atmospheric CO2 content since 1850 has been 18 percent. Major sinks for fossil fuel CO2 are the thermocline regions of large oceanic gyres. About 34 percent of the excess CO2 generated so far is stored in surface and thermocline gyre waters, and 13 percent has been advected into the deep sea. This leaves an airborne fraction of 53 percent.