This paper explores the interplay between the biophysical and economic geographies of climate change impacts on agriculture. It does so by bridging the extensive literature on climate impacts on yields and physical productivity in global crop production, with the literature on the role of adaptation through international trade in determining the consequences of climate change impacts. Unlike previous work in this area, instead of using a specific crop model or a set of models, we employ a statistical meta-analysis that encompasses all studies available to the IPCC-AR5 report. This permits us to isolate specific elements of the spatially heterogeneous biophysical geography of climate impacts, including the role of initial temperature, differential patterns of warming, and varying crop responses to warming across the globe. We combine these climate impact estimates with the Global Trade Analysis Project model of global trade in order to estimate the national welfare changes that are decomposed into three components: the direct (biophysical impact) contribution to welfare, the terms of trade effect, and the allocative efficiency effect. We find that when we remove the spatial variation in climate impacts, the terms of trade impacts are cut in half. Given the inherent heterogeneity of climate impacts in agriculture, this points to the important role of trade in distributing the associated welfare impacts. When we allow the biophysical impacts to vary across the empirically estimated uncertainty range taken from the meta-analysis, we find that the welfare consequences are highly asymmetric, with much larger losses at the low end of the yield distribution. This interaction between the magnitude and heterogeneity of biophysical climate shocks and their welfare effects highlight the need for detailed representation of both in projecting climate change impacts.

中文翻译：

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了解全球变暖对农业的福利影响及其驱动因素的空间分布

本文探讨了气候变化对农业影响的生物物理和经济地理之间的相互作用。它通过将关于气候对全球作物生产中产量和物理生产力影响的广泛文献与关于通过国际贸易进行适应在确定气候变化影响后果方面的作用的文献联系起来。与该领域以前的工作不同，我们没有使用特定的作物模型或一组模型，而是采用了统计荟萃分析，其中涵盖了 IPCC-AR5 报告中可用的所有研究。这使我们能够隔离气候影响的空间异质生物物理地理的特定元素，包括初始温度的作用、变暖的差异模式以及全球范围内作物对变暖的不同反应。我们将这些气候影响估计与全球贸易的全球贸易分析项目模型相结合，以估计分解为三个组成部分的国家福利变化：对福利的直接（生物物理影响）贡献、贸易条件影响和分配效率效应。我们发现，当我们去除气候影响的空间变化时，贸易条件的影响会减半。鉴于气候对农业影响的固有异质性，这表明贸易在分配相关福利影响方面的重要作用。当我们允许生物物理影响在从元分析中获得的经验估计的不确定性范围内变化时，我们发现福利后果是高度不对称的，在产量分布的低端有更大的损失。