My friend Wolfram Schlenker has written a paper with David Lobell and Justin Costa-Roberts that uses data from 1980 to the present to study how climate conditions affect agricultural production. The technical version is posted here.
“Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. Here, we show that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends for 1980–2008 exceeded one standard deviation of historic year-to-year variability. Models that link yields of the four largest commodity crops to weather indicate that global maize and wheat production declined by 3.8% and 5.5%, respectively, compared to a counterfactual without climate trends. For soybeans and rice, winners and losers largely balanced out. Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, CO2, fertilization, and other factors.”
These researchers are acting as an “early warning system”. By giving us a collective “heads up” about the challenges we are likely to face, they help us to adapt to climate change. Rather than being complacent about the future of our food supply, their estimates should make for profit “agribusiness” and farmers aware of the future impacts on yields and this will nudge that self interested actors into thinking about how to “change their game”. We can grow food in different places within a nation. Nations can import food from other locations and export other products for which they have a comparative advantage at. If we insist on continuing to use the same locations for growing food, then we will need to think about strategies that yield output that are less risky in the sense that yield is less sensitive to climate conditions. Economists are in deep thought about how “real world” farmers will cope with changing climate conditions. Here is an example from Africa. The authors collected detailed information on farming output and local climate conditions. Note that any set of correlations estimated do not represent “laws of physics”. If farmers become aware that they will face more extreme conditions then they can make investments to be prepared for them and such adaptation further lowers the yield costs of future climate shocks. The key here is to “plan ahead” and to have the resources to be able to invest so that you can “change your game”.