One of the principle claims of the Greening Earth Society — an astroturf organization fronting for the Western Fuels Association, which is itself fronting for Big Coal — is that the rise in atmospheric CO2 is going to increase global agricultural yields (thus the "greening"). A new study in Science casts serious doubt on this notion:

Long told SciDev.Net that the new results suggest that "the damaging effects of rising temperature and decreased soil moisture will not be offset by the fertilisation effect of rising CO2".