期刊名称：Discussion Paper Series / Department of Economics, New York University
出版年度：2007
卷号：1
出版社：New York University
摘要：There has been an active debate whether global warming will result in a net gain or net loss
for United States agriculture. With mounting evidence that climate is warming, we show
that such warming will have substantial impacts on agricultural yields by the end of the
century: yields of three major crops in the United States are predicted to decrease by 60
to 79% under the most rapid warming scenario. We use a 55-year panel of crop yields in
the United States and pair it with a unique ¡¥ne-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. The key contribution of our study is in identifying
a highly non-linear and asymmetric relationship between temperature and yields. Yields
increase in temperature until about 29¡ÀC for corn and soybeans and 33¡ÀC for cotton, but
temperatures above these thresholds quickly become very harmful, and the slope of the de-
cline above the optimum is signi¡¥cantly steeper than the incline below it. Previous studies
average temperatures over a season, month, or day and thereby dilute this highly non-linear
relationship. We use encompassing tests to compare our model with others in the literature
and ¡¥nd its out-of-sample forecasts are signi¡¥cantly better. The stability of the estimated
relationship across regions, crops, and time suggests it may be transferable to other crops
and countries.
关键词：Agriculture, Nonlinear temperature e.ects, Climate change.
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