Climate Science

Not an Easy Balancing Act

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Science  19 Apr 2002:
Vol. 296, Issue 5567, pp. 433
DOI: 10.1126/science.296.5567.433b

A commonly proposed strategy for sequestering atmospheric CO2 is increasing the mass of terrestrial vegetation, typically by reforestation or improved agricultural practices. One consequence of this approach would be a reduction of the amount of mineral dust injected into the atmosphere. Lower concentrations of atmospheric dust could, in turn, decrease the delivery of aeolian iron to the ocean, thereby reducing marine productivity in some regions and diminishing the rate of CO2 uptake. Therefore, increases in CO2 sequestration on land could produce decreases in CO2 uptake by the ocean. Ridgwell et al. use a global carbon cycle model to examine this antagonistic relation and find that the rate of oceanic uptake of anthropogenic CO2 could be decreased by as much as 9% by large-scale modification of terrestrial ecosystems. These results underline the importance of using integrated whole-Earth approaches for evaluating carbon dioxide reduction strategies, and show that carbon sequestration by land plants cannot be relied on as a substitute for emissions reductions.—HJS

Geophys. Res. Lett. 29, 10.1029/2001GL014304 (2002).

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