关键词: 综合环境风险, 气候变化, 综合区划

Abstract:

Environmental risks, such as crop failure, mortality and vegetation deterioration caused by warming, drought, flood, heatwave, etc., tend to be more complex and interactive with each other. Integrated Environmental Risk Regionalization becomes the fundament for multi-hazard prevention and reduction under a changing environment. Regarding potential large losses from the agricultural system, ecosystem, and human being caused by climate change, we assessed the integrated environmental risk based on the crop yield changes, ecosystem shift and mortality by heatwave in China during the late 21st century (2071-2099) under four Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). Bias-corrected projections of future climate change were derived from five generic circulation model. Four major crops (rice, wheat, maize, and soybean) were considered, and the crop yield changes were projected by four global gridded crop models. The changes of crop yield during 2071-2099 compared to the period of 1980-2010 were computed to identify the risk in agricultural system. The Γ metric was used to assess the risk of ecosystem shift under climate change. The Γ metric describes the ecosystem state and its changes based on a set of macroscopic variables derived from four global gridded vegetation models. The larger Γ, changes in ecosystem state variables, indicates the larger risk of ecosystem shift in future. A heatwave event was identified by three successive days of high temperature that >35 °C. The mortality rate caused by heatwave events was estimated by the difference of mortality rate in a period with high-temperature and that in non-high-temperature days of the year. Regression was established between heatwave events and mortality rates. It was then used for estimation of mortality rate in the 2071-2099 period. These environmental risks were combined by a multi-risk index (IERI) to illustrate the integrated environmental risk in the future. In this study, the same weights were set for all environmental risks in the IERI calculation. The IERI was calculated at a spatial resolution of 0.5° for the 2071-2099 period under the four RCPs. The results showed that high integrated environmental risks will appear in the Huang-Huai-Hai region, relatively high integrated environmental risks will appear in the South China, and moderate integrated environmental risks will occur in the Tibet region. The integrated environmental risk regions (IERR) were then delineated based on the assessment. Six IERRs were identified for China, i.e., Northwest-Low-Risk region, Northeast-Relatively-Low-Risk region, Tibet-Moderate-Risk region, Jin-Shaan-Moderate-Risk region, South-China-High-Risk region, and Huang-Huai-Hai-High-Risk region. Fourty-two sub regions were further divided upon the six IERRs. Due to largely different environmental conditions of the six IERRs, they include quite different numbers of sub regions, namely 2, 6, 8, 7, 10, and 9 subregions, respectively. Though many environmental risks caused by climate change were not included in this assessment, the preliminary integrated environmental risk regionalization would be a reference for decision makers and future studies.

Key words: integrated environmental risk, climate change, integrated regionalization