Organizations and Markets

Climate (Change) and Agricultural Adaptation

2 June 2008 at 2:09 pm Dick Langlois 2 comments

| Dick Langlois |

Just for the fun of it, I drove up to Cambridge on Friday to take in one day of an interesting NBER conference on Climate Change: Past and Present. The conference was organized by Gary Libecap, whom I’ve known for years, and Richard Steckel, whose work I have always read with interest. Steckel is one of the people who have pioneered the use of archaeological techniques in economic history, notably measuring the heights of skeletons for evidence on nutrition in historical populations.  This time he talked about using tree rings in historical research involving climate. 

There were several excellent papers, which are available at the conference website. The two I liked the best have a flavor of evolutionary economics as well as evolutionary biology. Richard Sutch talked about the history of hybrid corn in the U. S.  An important figure in the story is Henry Wallace, who founded one of the earliest hybrid-corn seed companies and, as Secretary of Agriculture, evangelized for hybrid corn and higher corn yields at the same time he was implementing pro-cyclical New Deal farm policies that restricted agricultural output in other commodities. But the main story is one of evolutionary learning.  The major midwestern droughts of 1934 and 1936 accidentally revealed the (unintended) benefits of one kind of hybrid corn that was resistant to drought, thus changing the perceived payoffs to farmers of adopting the new technology, whose primary benefit was ultimately increasing yields.

Perhaps the most interesting paper was by Alan Olmstead and Paul Rhode, part of their forthcoming book from Cambridge, Creating Abundance. They documented the amazing extent to which the history of agriculture in the United States has been one of adaptation to large climatic differences. It is a history in which “new biological technologies allowed North American farmers to push cropping into environments previously thought too arid, too variable, and too harsh to cultivate.” Between 1839 and 1929, the center of gravity of wheat cultivation moved 1,000 miles west and north, into areas between 4 and 15 degrees F colder in relevant averages. Over the same period, the center of gravity of corn production moved some 450 miles to the north-northwest into regions on average 5 degrees F colder. This adaptation took place in part through deliberate search but most often by trial-and-error learning and by accident, as when Mennonites discovered that the Turkey wheat they had brought with them from Russia grew well in Kansas. As the authors suggest, the temperature changes to which agriculture adapted are at least as large as those forecast for global warming. And the adaptation took place without the benefit of modern biotechnology.

Of course, historical adaptation was in the direction opposite to that predicted for global warming. And one paper did suggest that higher temperatures may have a non-linear adverse effect on crops, something that seemed to be true even in warmer areas where plants should have adapted to higher temperatures. But no one saw this as definitive, since the study wasn’t able to distinguish between temperature and moisture (as crops are grown successfully in California and Arizona at extremely high temperatures using irrigation), and since the entire study was set against the long history of adaptation in which cold not heat was the problem to be solved.

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