Stratospheric Aerosol Climate Intervention Designed to Minimize Negative Impacts

不断增加的温室气体(GHGs)会严重影响气候系统，并可能影响我们未来的生存。显而易见但困难的解决方案在于大幅遏制温室气体排放。如果做不到这一点，抵消温室气体导致的预期全球变暖的一个方法可能是地球工程。地球工程学中的一种策略是将硫酸盐气溶胶“注入”平流层以反射阳光。这一战略模拟了火山喷发期间的自然情况，可以缓解全球变暖。然而，它也可能产生意想不到的后果，如全球平均降水量减少，地表附近的紫外线(UV)辐射和臭氧浓度增加。这些后果可能会影响农业，改变粮食生产。该项目旨在了解硫酸盐气雾剂注射的不确定性，并评估其对农业的影响。如果确实需要地球工程学，了解这些影响是至关重要的。该项目的主要研究人员将利用NCAR共同体地球系统模式(CESM2)的全大气社区气候模式(CESM2)进行向平流层注入气溶胶的数值试验。然后，私人投资机构将探索如何引入注入以减少全球变暖，同时将硫酸盐气溶胶造成的平流层臭氧消耗对农业的影响降至最低。CESM2包括对漫射辐射、气溶胶和大气化学的完整处理，以及内置的作物生产模拟。PI将更新作物模型，以包括对紫外线的敏感性，并更好地表示臭氧破坏，这将允许更准确地表示作物影响。这项工作将支持地球工程模型对比项目(GeoMIP)，作为耦合模型对比项目6(CMIP6)的一部分。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Increasing greenhouse gases (GHGs) can strongly affect the climate system and potentially our future survival. The obvious, but difficult, solution lies in drastically curbing GHG emissions. Failing that, a way to offset the expected global warming induced by GHGs may be geoengineering. A strategy in geoengineering involves the "injection" of sulphate aerosols into the stratosphere to reflect sunlight. Mimicking what naturally occurs during volcanic eruptions, this strategy can mitigate global warming. However, it may also produce unintended consequences like reduced globally averaged precipitation and enhanced ultraviolet (UV) radiation and ozone concentration near the surface. These consequences can impact agriculture, altering food production. This project aims to understand the uncertainties of sulphate aerosol injection and evaluate its impacts on agriculture. Understanding these impacts is essential if geoengineering is indeed needed. The principal investigators (PIs) of this project will conduct numerical experiments of injecting aerosols into the stratosphere using the Whole Atmosphere Community Climate Model of the NCAR Community Earth System Model (CESM2). The PIs will then explore ways to introduce the injection to reduce global warming while minimizing impacts on agriculture that result from stratospheric ozone depletion due to sulfate aerosols. CESM2 includes complete treatment of diffuse radiation, aerosols, and atmospheric chemistry, as well as built in simulations of crop production. The PIs will update the crop model to include sensitivity to UV and to better represent ozone damage, which will allow more accurate representation of crop impacts. The work will support the Geoengineering Model Intercomparison Project (GeoMIP) as part of the Coupled Model Intercomparison Project 6 (CMIP6).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.