英文摘要: | Projecting the impacts of climate change on agriculture requires knowing or assuming how farmers will adapt. However, empirical estimates of the effectiveness of this private adaptation are scarce and the sensitivity of impact assessments to adaptation assumptions is not well understood1, 2. Here we assess the potential effectiveness of private farmer adaptation in Europe by jointly estimating both short-run and long-run response functions using time-series and cross-sectional variation in subnational yield and profit data. The difference between the impacts of climate change projected using the short-run (limited adaptation) and long-run (substantial adaptation) response curves can be interpreted as the private adaptation potential. We find high adaptation potential for maize to future warming but large negative effects and only limited adaptation potential for wheat and barley. Overall, agricultural profits could increase slightly under climate change if farmers adapt but could decrease in many areas if there is no adaptation. Decomposing the variance in 2040 projected yields and farm profits using an ensemble of 13 climate model runs, we find that the rate at which farmers will adapt to rising temperatures is an important source of uncertainty.
Determining the overall effectiveness of adaptation solutions in agriculture is challenging because it is impossible to accurately enumerate and model all economically feasible options. Further, the rate at which farmers will adopt these options in response to climate change remains uncertain1, 2, 3. As a result, the sensitivity of existing impact projections to assumptions of private farmer adaptation is not well understood. One promising approach to assess the potential of private adaptation in agriculture is to use past observations to simultaneously estimate two relationships between farm profits or yields and climate variables. The first is the long-term, equilibrium relationship based on cross-sectional variation in climate. Under the assumption that farmers have adjusted over the long-run to take full advantage of the climate they face, this response function captures the impacts from climate change if farmers are able to fully adapt using the set of available technologies4. The other is a short-term relationship based on interannual weather variation. As these weather shocks are transient and partially unanticipated, farmers can mitigate their effects only with a much more limited set of management options. Therefore, this response function gives the impacts from climate change if farmers are unable to implement long-run adaptations and instead respond to climate change as though it were simply unusual weather. Climate change impact projections made using these two response functions can be used to characterize the spread in impact projections resulting from uncertainty over how quickly farmers will adopt adaptive technologies and management practices already in use elsewhere5, 6. Here we apply this approach to data from Europe, and then estimate the impact of future temperature and precipitation changes on yields and farm profits with and without adaptation. We estimate equation (1) separately for each dependent variable (farm profits and the yields of five major crops) using balanced panel data sets (Methods). Figure 1 shows the results graphically.
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