I’m going to have to revise my skepticism about climate models. In at least one respect, their projections are spot on accurate. Satellite observations apparently validate model predictions that carbon dioxide (CO2) emissions will green the Earth.
That’s what four Australian scientists report in “Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments,” a study published in Geophysical Research Letters.
Models project that the 14% increase in atmospheric CO2 concentration from 1982 to 2010 would increase green foliage in warm, arid environments by 5-10%, and lo, satellites reveal an 11% increase that cannot be accounted for by other known factors.
As the researchers explain in the study’s abstract:
Satellite observations reveal a greening of the globe over recent decades. The role in this greening of the “CO2 fertilization” effect—the enhancement of photosynthesis due to rising CO2 levels—is yet to be established. The direct CO2 effect on vegetation should be most clearly expressed in warm, arid environments where water is the dominant limit to vegetation growth. Using gas exchange theory, we predict that the 14% increase in atmospheric CO2 (1982–2010) led to a 5 to 10% increase in green foliage cover in warm, arid environments. Satellite observations, analyzed to remove the effect of variations in precipitation, show that cover across these environments has increased by 11%. Our results confirm that the anticipated CO2 fertilization effect is occurring alongside ongoing anthropogenic perturbations to the carbon cycle and that the fertilization effect is now a significant land surface process.
Climate Cassandras warn that CO2-induced warming will make the planet browner (less hospital for plants and other growing things). So far, at least, the CO2-fertilization effect, especially the boost it gives to plant water-use efficiency, is more than offsetting adverse effects from rising global temperatures. And this CO2-related benefit appears to be truly global, greening warm, arid areas on all continents. The red areas* in the chart below show where the deserts are greening:
* I have no idea why the authors picked red to illustrate greening areas.