NASA - Drought Drives Decade-Long Decline in Plant Growth: "Earth has done an ecological about-face: Global plant productivity that once flourished under warming temperatures and a lengthened growing season is now on the decline, struck by the stress of drought.
NASA-funded researchers Maosheng Zhao and Steven Running, of the University of Montana in Missoula, discovered the global shift during an analysis of NASA satellite data. Compared with a six-percent increase spanning two earlier decades, the recent ten-year decline is slight -- just one percent. The shift, however, could impact food security, biofuels, and the global carbon cycle.
'We see this as a bit of a surprise, and potentially significant on a policy level because previous interpretations suggested that global warming might actually help plant growth around the world,' Running said."