Geoengineering as an optimization problem
Geoengineering as an optimization problem
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DOI：
10.1088/1748-9326/5/3/034009
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发表时间：
2010-07-01
影响因子：
6.7
通讯作者：
Caldeira, Ken
中科院分区：
文献类型：
--
作者：
Ban-Weiss, George A.;Caldeira, Ken
越来越多的证据表明，地球气候目前正在变暖，这主要是由于人类活动排放的温室气体造成的，预计地球将在本世纪继续变暖。科学家们已经开始研究地球工程降低地表温度的潜力，以及这些选择是否有助于减少环境风险。一种提出的方法涉及故意增加平流层中的气溶胶负荷，以将额外的阳光散射到太空。先前的建模研究试图预测平流层中假设的气溶胶增加所造成的气候后果。这些研究表明，这种方法可能会降低地表温度，但无法在高二氧化碳世界中重建低二氧化碳气候。在这项研究中，我们试图确定平流层气溶胶的纬度分布，尽管二氧化碳水平很高，但这种气溶胶最接近实现低二氧化碳气候。使用NCAR CAM3.1大气环流模型，我们发现极地地区的平流层气溶胶负荷高于热带地区，导致温度分布比全球均匀负荷产生的温度分布更类似于低二氧化碳气候。然而，平流层硫酸盐的这种极权重往往会降低水文循环的恢复程度，因此对改善低二氧化碳气候的恢复没有显着贡献。在该模型中，最佳的纬度变化气溶胶分布将二氧化碳加倍导致的均方根地带平均陆地温度变化减少了 94%，将均方根地带平均陆地降水量减去蒸发量变化减少了 74%。值得注意的是，这项理想化的研究代表了利用大气环流模型优化气候工程的首次尝试。不确定性很高，并且并非所有现实中重要的过程都被建模。
There is increasing evidence that Earth's climate is currently warming, primarily due to emissions of greenhouse gases from human activities, and Earth has been projected to continue warming throughout this century. Scientists have begun to investigate the potential for geoengineering options for reducing surface temperatures and whether such options could possibly contribute to environmental risk reduction. One proposed method involves deliberately increasing aerosol loading in the stratosphere to scatter additional sunlight to space. Previous modeling studies have attempted to predict the climate consequences of hypothetical aerosol additions to the stratosphere. These studies have shown that this method could potentially reduce surface temperatures, but could not recreate a low-CO2 climate in a high-CO2 world. In this study, we attempt to determine the latitudinal distribution of stratospheric aerosols that would most closely achieve a low-CO2 climate despite high CO2 levels. Using the NCAR CAM3.1 general circulation model, we find that having a stratospheric aerosol loading in polar regions higher than that in tropical regions leads to a temperature distribution that is more similar to the low-CO2 climate than that yielded by a globally uniform loading. However, such polar weighting of stratospheric sulfate tends to degrade the degree to which the hydrological cycle is restored, and thus does not markedly contribute to improved recovery of a low-CO2 climate. In the model, the optimal latitudinally varying aerosol distributions diminished the rms zonal mean land temperature change from a doubling of CO2 by 94% and the rms zonal mean land precipitation minus evaporation change by 74%. It is important to note that this idealized study represents a first attempt at optimizing the engineering of climate using a general circulation model; uncertainties are high and not all processes that are important in reality are modeled.