Adaptation, Spatial Heterogeneity, and the Vulnerability of Agricultural Systems to Climate Change and CO2 Fertilization: An Integrated Assessment Approach

In this paper we develop economic measures of vulnerability to climate change with and without adaptation in agricultural production systems. We implement these measures using coupled, site-specific ecosystem and economic simulation models. This modeling approach has two key features needed to study the response of agricultural production systems to climate change: it represents adaptation as an endogenous, non-marginal economic response to climate change; and it provides the capability to represent the spatial variability in bio-physical and economic conditions that interact with adaptive responses. We apply this approach to the dryland grain production systems of the Northern Plains region of the United States. The results support the hypothesis that the most adverse impacts on net returns distributions tend to occur in the areas with the poorest resource endowments and when mitigating effects of CO₂ fertilization and adaptation are absent. We find that relative and absolute measures of vulnerability depend on complex interactions between climate change, CO₂ level, adaptation, and economic conditions such as relativeoutput prices. The relationship between relative vulnerability and resource endowments varies with assumptions about climate change, adaptation, and economic conditions. Vulnerability measured with respect to an absolute threshold is inversely related to resource endowments in all cases investigated.     

近千年来三个气候特征时期东亚夏季风的模拟对比

利用全球海气耦合气候模式ECHO-G的近千年连续积分资料,选取与降水关系较好的东亚夏季风指数,对不同气候特征时期的东亚环流及季风影响因子进行了探讨.结果表明用海陆热力差异定义的东亚夏季风指数Isun在年际尺度上较好地体现了长江流域及华北地区降水的变化,而利用850 hPa纬向风场定义的指数Iwang在年代际尺度上较好地体现了长江流域的降水变化.从不同气候特征时期的环流来看,中世纪暖期夏季风最强,东亚大陆降水明显偏多,现代暖期夏季风较之有所减弱,而小冰期则是夏季风最弱的时期,东亚大陆的降水明显偏少.不同气候特征时期夏季风指数与海温的相关表明,ENSO事件对东亚夏季风的影响在现代暖期有所增强,而与外部强迫因子的相关揭示出中世纪暖期有效太阳辐射变化是影响东亚夏季风变化的主要因子,现代暖期则是温室气体对夏季风的影响更重要.