The Economist gives a positive spin to the article ““Nonlinear heat effects on African maize (corn) as evidenced by historical yield trials”, Lobell et al.” in Nature : Climate Change. I posted the following comment:-
Experimental conditions must be controlled to get comparable results. But this is not real world conditions. In the real world farmers will seek to optimize output given the constraints. When temperature, or rainfall changes, farmers will adapt. It is part of the human condition to adapt, which is why there is agriculture to be found in Southern Sweden and the blazing heat of Minas Gerais. Corn production is to be found in Edinburg, Texas with 136 days a year above 30 degrees. This is achieved through both planting and harvesting earlier in the year than further north.
As well as looking to the negatives of warming, we should look to the positives. More temperate climates should, ceteris paribus, see increasing yields as temperatures get warmer. For instance, Northern Europe, the Steppes of Central Asia and the Canadian plains should benefit from higher temperatures. Also higher temperatures will be caused by higher CO2 levels. Experimental studies have shown a doubling of CO2 will increase maize biomass by around a third. Finally, according to Al Gore, precipitation increased by 20% in the last century, mostly in above mentioned areas, Southern South America and SE Australia.
One of the biggest risks for climate change is supposedly to the stability world food supplies, with possible famines. But, as Amartya Sen has shown, the biggest famines are made serious not by natural factors but by adverse terms of trade. The Bengal famine of 1943, in which more than 3 million died, was exacerbated by a ban on exports between provinces in India, at the same time as extra demand was present from those supplying the troops fighting in Burma.
Al Gore : An Inconvenient Truth pages 114-115