Global Policy Laboratory, Goldman School of Public Policy, University of California, Berkeley, Berkeley, CA, USA.
Department of Agricultural and Resource Economics, University of California, Berkeley, Berkeley, CA, USA.
Nature. 2018 Aug;560(7719):480-483. doi: 10.1038/s41586-018-0417-3. Epub 2018 Aug 8.
Solar radiation management is increasingly considered to be an option for managing global temperatures, yet the economic effects of ameliorating climatic changes by scattering sunlight back to space remain largely unknown. Although solar radiation management may increase crop yields by reducing heat stress, the effects of concomitant changes in available sunlight have never been empirically estimated. Here we use the volcanic eruptions that inspired modern solar radiation management proposals as natural experiments to provide the first estimates, to our knowledge, of how the stratospheric sulfate aerosols created by the eruptions of El Chichón and Mount Pinatubo altered the quantity and quality of global sunlight, and how these changes in sunlight affected global crop yields. We find that the sunlight-mediated effect of stratospheric sulfate aerosols on yields is negative for both C4 (maize) and C3 (soy, rice and wheat) crops. Applying our yield model to a solar radiation management scenario based on stratospheric sulfate aerosols, we find that projected mid-twenty-first century damages due to scattering sunlight caused by solar radiation management are roughly equal in magnitude to benefits from cooling. This suggests that solar radiation management-if deployed using stratospheric sulfate aerosols similar to those emitted by the volcanic eruptions it seeks to mimic-would, on net, attenuate little of the global agricultural damage from climate change. Our approach could be extended to study the effects of solar radiation management on other global systems, such as human health or ecosystem function.
太阳能辐射管理正日益被视为一种管理全球气温的选择，然而，通过将阳光散射回太空来改善气候变化的经济影响在很大程度上仍然未知。尽管太阳能辐射管理可以通过减少热应激来提高作物产量，但伴随而来的阳光可利用量变化的影响从未经过实证估计。在这里，我们利用激发现代太阳能辐射管理提案的火山爆发作为自然实验，首次估计了由 El Chichón 和 Mount Pinatubo 火山爆发产生的平流层硫酸盐气溶胶如何改变全球阳光的数量和质量，以及这些阳光变化如何影响全球作物产量。我们发现，平流层硫酸盐气溶胶对 C4（玉米）和 C3（大豆、水稻和小麦）作物产量的阳光介导效应是负面的。我们将我们的产量模型应用于基于平流层硫酸盐气溶胶的太阳能辐射管理情景，发现由于太阳能辐射管理导致的阳光散射而预计在二十一世纪中叶造成的损害与冷却带来的益处大致相当。这表明，如果使用类似于试图模拟的火山爆发所排放的平流层硫酸盐气溶胶来部署太阳能辐射管理，那么它将不会减轻气候变化对全球农业造成的损害。我们的方法可以扩展到研究太阳能辐射管理对其他全球系统（如人类健康或生态系统功能）的影响。
