Climate Economics Seminar: Estimating the Effect of Climate Change on Crop Yields and Farmland Values: The Importance of Extreme Temperatures
Date(s): February 12, 2008 (1 pm)
Location: Room 4144, EPA West
Presenter: Wolfram Schlenker (Columbia University)
Description: Prof. Schlenker summarized a paper written with Anthony Fisher, Michael Hanemann, and Michael Roberts. The paper pairs a panel of yearly crop yields in the United States with a fine-scale weather data set that incorporates the whole distribution of temperatures between the minimum and maximum within each day and across all days in the growing season. Yields increase in temperature until about 29°C for corn, 30°C for soybeans, and 32°C for cotton, but temperatures above these thresholds become very harmful. The slope of the decline above the optimum is significantly steeper than the incline below it. This has strong implications for global warming which is predicted to increase the frequency of temperatures above the critical threshold that are harmful for yields. Area-weighted average yields given current growing regions are predicted to decrease by 31-43% under the slowest warming scenario and 67-79% under the most rapid warming scenario by the end of the century. There is limited potential for adaptation within a crop species as the same nonlinear and asymmetric relationship is found if we look only at the time series or cross-section, and the latter should pick up how farmers adapt to warmer climates.
A cross-sectional analysis of farmland values that accounts for an even wider set of adaptation possibilities gives comparable, robust impacts. Mean impacts range from a 27 decrease under the slow warming scenario to a 69 decrease under the fast warming scenario by the end of the century. The increased frequency of very hot temperatures is again responsible for the largest share of the predicted impacts.
Presentation Slides (PDF) (4,939 kb, About PDF)