Does Directed Innovation Mitigate Climate Damage? Evidence from U.S. Agriculture
中文摘要
本文聚焦美国农业，研究创新如何应对气候变化并塑造其经济影响。我们通过模型表明，定向创新既可能减轻也可能加剧气候变化的潜在经济损害，具体取决于新技术与有利气候条件之间的可替代性。为实证考察技术对气候变化的响应，我们测度了各作物对破坏性极端温度的暴露程度，以及体现于新品种发布和专利中的作物特定创新。我们发现，自20世纪中叶以来，创新已转向暴露于极端温度程度不断上升的作物。此外，这一效应主要由与环境适应最相关的农业技术类型所驱动。我们进而表明，美国各县对诱致性创新的暴露显著减弱了极端温度造成的当地经济损害。将这些估计结果与模型结合，我们发现，自1960年以来，定向创新已抵消了破坏性气候趋势可能导致的美国农业用地价值损失的20%，并且创新有望抵消到2100年预计损害的13%。这些发现凸显了内生技术变迁作为气候变化适应途径的重要性，但也表明其效果并不完全。
Abstract
Abstract This article studies how innovation reacts to climate change and shapes its economic impacts, focusing on U.S. agriculture. We show in a model that directed innovation can either mitigate or exacerbate climate change’s potential economic damage depending on the substitutability between new technology and favorable climatic conditions. To empirically investigate the technological response to climate change, we measure crop-specific exposure to damaging extreme temperatures and crop-specific innovation embodied in new variety releases and patents. We find that innovation has redirected since the mid-twentieth century toward crops with increasing exposure to extreme temperatures. Moreover, this effect is driven by types of agricultural technology most related to environmental adaptation. We next show that U.S. counties’ exposure to induced innovation significantly dampens the local economic damage from extreme temperatures. Combining these estimates with the model, we find that directed innovation has offset 20% of potential losses in U.S. agricultural land value due to damaging climate trends since 1960 and that innovation could offset 13% of projected damage by 2100. These findings highlight the vital importance, but incomplete effectiveness, of endogenous technological change as a source of adaptation to climate change.