The potential storage of carbon caused by eutrophication of the biosphere

We use an element-matching approach to examine the hypothesis that the rate of atmospheric CO₂ increase has been reduced by an increased net storage of carbon in forests, coastal oceans, and the open sea caused by eutrophication of the biosphere with nitrogen and phosphorus. We conclude that a reasonable upper limit of about 200 Tg of the estimated total of 7800 Tg of CO₂-carbon released to the atmosphere in 1980 could have been stored in biotic reservoirs as organic carbon in trees, soils, and aquatic sediments as a consequence of eutrophication. The reason that storage is so limited relative to total carbon release is that the C:N and C:P ratios in the CO₂-carbon sources (fossil fuels and primary forests) are much larger than the ratios in the sinks (regrowing forests and aquatic sediments) and that N and P supply controls the rate and amount of storage of organic carbon in the available biotic sinks.