Projected Changes in the Annual Range of Precipitation Under Stabilized 1.5°C and 2.0°C Warming Futures

Abstract

Changes in hydrological cycle under 1.5°C and 2.0°C warming are of great concern on the post-Paris Agreement agenda. In particular, the annual range of precipitation, that is, the difference between the wet and dry seasons, is important to society and ecosystem. This study examines the changes in precipitation annual range using the Community Earth System Model low-warming (CESM-LW) experiment, designed to assess climate change at stabilized 1.5°C and 2.0°C warming levels. To reflect the exact annual range in different regions, wet and dry seasons are defined for each grid point and year. Based on this metric, the precipitation annual range would increase by 3.90% (5.27%) under 1.5°C (2.0°C) warming. The additional 0.5°C of warming would increase annual range of precipitation by 1.37%. The enhancement is seen globally, except in some regions around the subtropics. Under the additional 0.5°C of warming, a significant increase in the annual range occurs over 15% (22%) of the ocean (land) regions. The increase is associated with the enhanced precipitation during wet season. Moisture budget analysis shows that the enhancement in annual range is dominated by vertical moisture advection, which includes thermodynamic (TH, moisture) and climate dynamic (CD, circulation changes) terms. The TH term plays a dominant role, while the CD term partly offsets the effects of the TH term. The TH term dominates over most regions except for part of the tropical ocean and some of the land regions, where the CD term is also remarkable. Thus, the enhancement of the annual range of precipitation is mainly caused by the increase in moisture. Plain Language Summary The Paris Agreement proposed a target to limit global warming to less than 2°C and pursue efforts to limit warming to less than 1.5°C. Since then, great effort has been devoted to exploring the impacts of the 1.5°C and 2.0°C warming scenarios. The changes in the seasonal cycles of precipitation have important impacts on natural and human systems but are unknown under 1.5°C and 2°C warming levels. We focus on the changes in the annual range of precipitation, which represents seasonal cycle and is defined as the difference between wet and dry seasonal rainfall in which the wet and dry seasons vary spatially and temporally. We project the changes by using CESM low-warming experiments. In the experiments, the multiyear global mean surface temperatures will stabilize at 1.5°C and 2.0°C above the preindustrial level by the end of the 21st century. We find significant increases in seasonal cycle over both ocean and land. The increase is dominated by the enhancement of precipitation during wet season. The increased seasonal cycle is caused by the increase in water vapor over most regions except for part of the tropical ocean and some of the land regions, where the effects of circulation changes are remarkable.

Divergent Responses of Summer Precipitation in China to 1.5°C Global Warming in Transient and Stabilized Scenarios

“…There are also a few recent studies reported in the literature (Lee et al, 2018;Chen et al, 2018;Li et al, 2019;Chen et al, 2020) to assess changes of the East Asian summer monsoon system in the stabilized 1.5°C and 2°C warmer worlds. Although results from the stabilized and transient scenarios are qualitatively consistent in projecting an increased frequency and intensity of extreme precipitation over East Asia, there exist significant differences in the response of summer monsoon and in the spatial…”

“…There are also a few recent studies reported in the literature (L. Chen et al, 2018, Z. Chen et al, 2020Lee et al, 2018;D. Li et al, 2019) to assess changes of the East Asian summer monsoon system in the stabilized 1.5°C and 2°C warmer worlds.…”

Future changes in precipitation extremes across China based on CMIP6 models

“…The experimental outputs from the CMIP6 models contain more sophisticated and modified parameterization schemes for dynamic processes and have designed new emission scenarios for the projections (O'Neill et al ., 2014; Kawai et al ., 2019; Park et al ., 2019; Gusain et al ., 2020). Efforts on the assessments and future projection of climate extremes have been implemented recently by using CMIP6 models (Jiang et al ., 2020; Chen et al ., 2020a, 2020b, 2020c, 2020d). Chen et al .…”

Future Climate Change Hotspots Under Different 21st Century Warming Scenarios

“…There is increasing interest in measuring the regional responses to climate change to understand how these may vary for different levels of global warming. Prior research has shown that both observed and projected changes in surface temperatures and precipitation exhibit large regional variations, and spatial features of precipitation changes are even more regionally variable than changes in temperature (Adler & Gu, 2015; Chen et al., 2020; Contractor et al., 2020; Dunn et al., 2020; Feng et al., 2014; Gao et al., 2020). To facilitate decision‐making on mitigation and adaptation strategies and formulate warming targets to avoid unacceptable climate change, it is necessary to understand and quantify potential spatial heterogeneity in the climate change response.…”