Double cropping as an adaptation to climate change in the United States
研究了美国农民在气候变暖下增加双季种植（冬小麦-大豆）的倾向，发现3°C升温使双季大豆面积占比提高2.1个百分点，但双季大豆单产比单季低12%，收入仅增加1.3%，只能小幅抵消产量下降的损失。
Abstract A warming climate expands the frost‐free season, plausibly allowing for increased cropping intensity in temperate regions. This paper assesses the potential of multiple cropping to offset the projected negative effects of climate change on agricultural yields in the United States. We use cross‐sectional variation in observed land cover, soil characteristics, and climate to estimate farmers' propensity to double‐crop winter wheat with soybeans. Our estimates imply that under current economic conditions, a 3°C warming would result in an increase of 2.1 percentage points in the share of current soybean area double cropped, primarily driven by expansions in cooler regions. A fixed‐effects panel model of county yields further indicates that yields of double‐cropped soybeans are about 12% lower than those of single‐cropped soybeans. Accounting for changes in cropping intensity and attendant effects on soybean yields, we project that at current prices, a 3°C warming would induce a shift in cropping intensity that increases revenue from soy systems by 1.3% overall, offsetting only a small fraction of the revenue impacts of predicted yield declines.