The economic effects of global warming have gained considerable attention in the recent economic literature. While the relationship between rainfall and agriculture is well known, precipitations alone do not capture the soil water availability, which depends on the evaporation of the water (potential evapotranspiration [PET]). This paper presents evidence of the relationship between aridification and agricultural productivity. We show that areas that have experienced increased precipitations have become arider due to increased PET. We then project future aridification patterns. We find that the global arid area will increase by 3.9 per cent by 2040. This implies a global loss of about 20 million tons of maize, 19 million tons of rice, 8 million tons of soybeans and 21 million tons of wheat until 2040 if no action to combat desertification is taken.

中文翻译：

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干旱化、降水和作物生产力：来自干旱指数的证据

全球变暖的经济影响在最近的经济文献中引起了相当大的关注。虽然降雨与农业之间的关系众所周知，但仅靠降水并不能反映土壤水分的有效性，这取决于水的蒸发（潜在蒸散 [PET]）。本文提供了干旱化与农业生产力之间关系的证据。我们表明，由于 PET 增加，降水量增加的地区变得更加干燥。然后我们预测未来的干旱化模式。我们发现，到 2040 年，全球干旱面积将增加 3.9%。这意味着，如果不这样做，到 2040 年全球将损失约 2000 万吨玉米、1900 万吨大米、800 万吨大豆和 2100 万吨小麦。采取行动防治荒漠化。