Atmospheric Science

Green Gains

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Science  28 Jun 2013:
Vol. 340, Issue 6140, pp. 1501
DOI: 10.1126/science.340.6140.1501-b

Satellite-based observations have shown that many regions of the terrestrial biosphere are getting greener; i.e., their above-ground vegetative mass is increasing. A number of factors, including changes in light, water, nutrients, and land use, could be causing that trend, although the most obvious cause would seem to be the rising concentration of CO2 in the atmosphere. Donohue et al. used gas exchange theory, which links vegetation mass to the concentration of atmospheric CO2 through its effect on the water use efficiency of plants, to predict that the increase of atmospheric CO2 between 1982 and 2010 should have produced an increase in the amount of green foliage between 5 and 10%. The authors then confirmed, based on satellite measurements, that the amount of vegetation increased by about 11% in warm, arid environments, where other factors affecting greenness should be unimportant. Although these findings cannot be used to explain changes in greenness in other regions, where different drivers may control vegetation, the principle still applies, and so the challenge is to develop a more general understanding of how increasing CO2 is affecting vegetation in other environments, where the other forcing factors are more important.

Geophys. Res. Lett. 10.1002/grl.50563 (2013).

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