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We project drought losses in China under global temperature increase of 1.5 °C and 2.0 °C, based on the Standardized Precipitation Evapotranspiration Index (SPEI) and the Palmer Drought Severity Index (PDSI), a cluster analysis method, and "intensity-loss rate" function. In contrast to earlier studies, to project the drought losses, we predict the regional gross domestic product under shared socioeconomic pathways instead of using a static socioeconomic scenario. We identify increasing precipitation and evapotranspiration pattern for the 1.5 °C and 2.0 °C global warming above the preindustrial at 2020-2039 and 2040-2059, respectively. With increasing drought intensity and areal coverage across China, drought losses will soar. The estimated loss in a sustainable development pathway at the 1.5 °C warming level increases 10-fold in comparison with the reference period 1986-2005 and nearly threefold relative to the interval 2006-2015. However, limiting the temperature increase to 1.5 °C can reduce the annual drought losses in China by several tens of billions of US dollars, compared with the 2.0 °C warming., Competing Interests: The authors declare no conflict of interest., (Copyright © 2018 the Author(s). Published by PNAS.)

Regional precipitation patterns may change in a warmer climate, thereby increasing flood and drought risks. In this paper, annual, annual maximum, intense, heavy, moderate, light, and trace precipitation are employed as indicators to assess changes in precipitation patterns under two scenarios in which the global mean temperature increases by 1.5 °C and 2.0 °C relative to pre-industrial levels using the regional climate model COSMO-CLM (CCLM). The results show that annual precipitation in China will be approximately 2.5% higher under 1.5 °C warming relative to the present-day baseline (1980–2009), although it will decrease by approximately 4.0% under an additional 0.5 °C increase in global mean temperature. This trend is spatially consistent for regions with annual precipitation of 400–800 mm, which has experienced a drying trend during the past half century; thus, limiting global warming to 1.5 °C may mitigate these drying conditions. The annual maximum precipitation continues to increase from present day levels to the 2.0 °C warming scenario. Relative to the baseline period, the frequency of trace and light precipitation days exhibits a negative trend, while that of moderate, heavy, and intense precipitation days has a positive trend under the 1.5 °C warming scenario. For the 2.0 °C warming world, the frequency of days is projected to decrease for all precipitation categories, although the intensity of intense precipitation increases. Spatially, a decrease in the number of precipitation days is expected to continue in central and northern China, where a drying trend has persisted over the past half century. Southeastern China, which already suffers greatly from flooding, is expected to face more heavy and intense precipitation with an additional 0.5 °C increase in global mean temperature. Meanwhile, the intensity of intense precipitation is expected to increase in northern China, and the contribution of light and moderate precipitation to the annual precipitation is expected to decrease in southeastern China. Therefore, flood risk in northern China and drought risk in southern China should draw more attention for a global air temperature increase from 1.5 °C to 2.0 °C. [ABSTRACT FROM AUTHOR]

Based on outputs from regional climate model COSMO-CLM (CCLM), climate conditions in the Haihe River Basin (HRB) under the 1.5 and 2.0 °C global warming scenarios were projected. Drought characteristics were analyzed by the Standardized Precipitation Evapotranspiration Index (SPEI), and population exposure to regional droughts in the warming world were then assessed by a combination of the population in 2010. It was revealed that both annual precipitation and potential evapotranspiration will increase in the 1.5 °C warming level relative to the reference period of 1986–2005 in the HRB. But annual precipitation was projected to decrease in the 2.0 °C warming level, although potential evapotranspiration was projected to increase. The temperature in the HRB was projected to rise faster than the global mean, and the timing of the regional 2.0 °C warming level will come earlier. Under the global warming of 1.5 °C, intensity and coverage of droughts in the HRB exhibit no significant trends relative to 1986–2005, while the drought frequency might decrease to a certain degree. Under the global warming of 2.0 °C, intensity and coverage of droughts will increase notably. In particular, drought coverage in the 2.0 °C level will be 1.9 times larger than that of the 1.5 °C scenario. Drought frequency under the 2.0 °C warming scenario will increase relative to the 1.5 °C warming scenario but still be less than that of the reference period. As a result, population exposure to droughts in the 1.5 °C warming level could be reduced by 30.4% relative to the 1986–2005 period, but increase by 74.8% in the 2.0 °C warming level. Seasonally, an increasing trend of exposure to severe droughts in summer, autumn and winter was projected in the 1.5 °C global warming level, while that to extreme droughts in summer and winter will decrease. Under 2.0 °C global warming scenario, increasing trend of severe and extreme droughts was projected in spring, autumn and winter. And the exposure to extreme droughts in autumn and winter might be doubled relative to the reference period. Similar spatial distribution patterns were found for population exposure in 1.5 °C and 2 °C global warming levels with high values projected in south and central basin but low in north and west. But the difference is, less population will be exposed to droughts in most area of HRB under 1.5 °C warming scenario, while population exposure will be larger under 2.0 °C global warming scenario relative to 1986–2005. The additional 0.5 °C from 1.5 °C to 2.0 °C will obviously increase the drought risks, especially in the southern and central HRB. Considering the projections that more drought risks might exist under the 2.0 °C warming scenario than in the 1.5 °C level, a perspective to keep the increase in global mean temperature below 2.0 °C and limit it to 1.5 °C, has far-reaching implications to socioeconomic development in the HRB. [ABSTRACT FROM AUTHOR]