What was done
The authors examined potential climate change impacts on the productivity of five major crops (canola, corn, potato, rice and winter wheat) of eastern China (30 to 42°N, 108 to 123°E) via full-domain simulations of the EPIC agro-ecosystem model for the baseline period AD 1961-1990 and the future period AD 2071-2100 under the IPCC's A2 scenario for projected air CO2 concentrations and accompanying climate change (both with and without the CO2 fertilization effect).

What was learned
Chavas et al. determined that "without the enhanced CO2-fertilization effect, potential productivity declines in all cases ranging from 2.5 to 12%," although "interannual yield variability remains constant or declines in all cases except rice." However, they report that when the CO2-fertilization effect is included, as it must be in a CO2-enriched world, "aggregate potential productivity (i.e. if the crop is grown everywhere) increases 6.5% for rice, 8.3% for canola, 18.6% for corn, 22.9% for potato, and 24.9% for winter wheat." And they add that "similar results are reported at the national scale in the work of Lin et al. (2005) using alternative RCM output and the CERES crop simulation model."

What it means
Even in the face of the deleterious climate changes predicted to occur over the rest of the 21st century, when the concomitant aerial fertilization effect of the projected increase in the air's CO2 content is factored into the validated yield model employed by the seven scientists, the net productivities of all five crops - when grown everywhere - rise over the entire study region, which should be a tremendous blessing to the people of China. And if they use but a modicum of ingenuity and slightly adjust the areas where different crops are preferentially grown, the benefits can be expected to be even larger ... which should all add up to a big blessing for a big country.

Reference
Lin, E., Xiong, W., Ju, H., Xu, Y., Li, Y., Bai, L. and Liyong, X. 2005. Climate change impacts on crop yield and quality with CO2 fertilization in China. Philosophical Transactions of the Royal Society B 360: 2149-2154.