Drylands climate response to transient and stabilized 2 °C and 1.5 °C global warming targets
Drylands are one of the most sensitive areas to climate change. Many previous studies assessed the impact of 1.5 °C and 2 °C warming targets using transient warming scenarios by representative concentration pathways of CMIP5. Here we compared the climate changes over global drylands in transient and stabilized 1.5 °C and 2 °C warmer worlds using Community Earth System Model simulations. The projections indicate a warming of 2.3 °C (1.6 °C) over drylands could occur in a stabilized 2 °C (1.5 °C) warmer world by the end of this century. The warming in drier regions is higher and the hyper-arid areas would experience warming of 2.4 °C (1.8 °C). Comparing the 2 °C to 1.5 °C warming targets, the additional 0.5 °C warming will lead to ~ 1.0 °C warming in drylands of Eurasia and North America. Responding to the 2 °C warming, the increased precipitation (21.8–42.6 mm/year) is not enough to offset the increased PET (88.3–101.7 mm/year) over drylands, resulting in the drylands expansion, and the additional 0.5 °C global warming will aggravate the drought in drylands in southern North America and North Africa. Compared to the stabilized 2 °C warming target, controlling the global warming to within 1.5 °C will reduce the warming in drylands by 0.7 °C, and reduce the drylands expansion relative to 1961–1990 by ~ 44%. Compared to the stabilized warming scenarios, the temperature response and drylands area coverage increase are higher in the transient warming scenarios, but the difference of temperature caused by additional 0.5 °C global warming and the precipitation increase in drylands are lower.
KeywordsDrylands climate change Transient and stabilized warming world 1.5 °C and 2 °C warming target The Paris Agreement
This work was jointly supported by the Natural Science Foundation of China (41705077), China Postdoctoral Science Foundation (2017M613250) and the National Key Research and Development Program of China (2017YFC1502305). The authors acknowledge the GPCC and PRECL precipitation data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd/, the CRU TS 3.25 precipitation and PET data, the CPC PET data provided by Feng and Fu (2013), the GISS temperature data developed by NOAA, the National Center for Atmospheric Research (NCAR) for producing the CESM model simulations and making them available for analysis. More information about the data from models used in this study is available on the following website: CESM1.1.1-CAM5 historical and RCP model output (http://www.cesm.ucar.edu/experiments/1.5-2.0-targets.html), CESM1-CAM5 LW1.5deg and LW2deg model output (https://www.earthsystemgrid.org/search.html). We thank Lei Lin for help with obtaining CESM data.
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