Abstract
The Coupled Model Intercomparison Project Phase 6 (CMIP6) dataset is used to examine projected changes in temperature and precipitation over the United States (U.S.), Central America and the Caribbean. The changes are computed using an ensemble of 31 models for three future time slices (2021–2040, 2041–2060, and 2080–2099) relative to the reference period (1995–2014) under three Shared Socioeconomic Pathways (SSPs; SSP1-2.6, SSP2-4.5, and SSP5-8.5). The CMIP6 ensemble reproduces the observed annual cycle and distribution of mean annual temperature and precipitation with biases between − 0.93 and 1.27 °C and − 37.90 to 58.45%, respectively, for most of the region. However, modeled precipitation is too large over the western and Midwestern U.S. during winter and spring and over the North American monsoon region in summer, while too small over southern Central America. Temperature is projected to increase over the entire domain under all three SSPs, by as much as 6 °C under SSP5-8.5, and with more pronounced increases in the northern latitudes over the regions that receive snow in the present climate. Annual precipitation projections for the end of the twenty-first century have more uncertainty, as expected, and exhibit a meridional dipole-like pattern, with precipitation increasing by 10–30% over much of the U.S. and decreasing by 10–40% over Central America and the Caribbean, especially over the monsoon region. Seasonally, precipitation over the eastern and central subregions is projected to increase during winter and spring and decrease during summer and autumn. Over the monsoon region and Central America, precipitation is projected to decrease in all seasons except autumn. The analysis was repeated on a subset of 9 models with the best performance in the reference period; however, no significant difference was found, suggesting that model bias is not strongly influencing the projections.
Highlights
Climate change is one of the greatest challenges faced by humankind as it poses an existential threat to many aspects of the current social–ecological landscape of natural and human systems
Srivastava et al (2020) evaluated daily characteristics of precipitation in the historical period and concluded that most Coupled Model Intercomparison Project Phase 6 (CMIP6) models overestimate the occurrence and variability of wet spell durations over the western U.S while they underestimate the occurrence of dry spells over most of the southern U.S Likewise, Akinsanola et al (2020) noted that CMIP6 models showed relatively better skill in the simulation of warm season extreme precipitation over the U.S studies focused on the evaluation of future CMIP Phase 5 (CMIP5) climatic changes over the North and Central America and the Caribbean are relatively limited and mostly far have focused on the North American monsoon that exhibits drying in response to increase in radiative forcing (Jin et al 2020; He et al 2020; Wang et al 2020a, b)
A study assessing the CMIP6 models performance and their simulated precipitation and temperature changes in the twenty-first century over the region encompassing the contiguous U.S, Central America, and the Caribbean, is currently lacking. This study addresses these gaps by assessing the future climate responses at a subregional scale over these regions through the analysis of a large suite of CMIP6 General circulation models (GCMs) under various Shared Socioeconomic Pathways/Representative Concentration Pathways (SSP/RCP) scenarios
Summary
Climate change is one of the greatest challenges faced by humankind as it poses an existential threat to many aspects of the current social–ecological landscape of natural and human systems. Srivastava et al (2020) evaluated daily characteristics of precipitation in the historical period and concluded that most CMIP6 models overestimate the occurrence and variability of wet spell durations over the western U.S while they underestimate the occurrence of dry spells over most of the southern U.S Likewise, Akinsanola et al (2020) noted that CMIP6 models showed relatively better skill in the simulation of warm season extreme precipitation over the U.S studies focused on the evaluation of future CMIP5 climatic changes over the North and Central America and the Caribbean are relatively limited and mostly far have focused on the North American monsoon that exhibits drying in response to increase in radiative forcing (Jin et al 2020; He et al 2020; Wang et al 2020a, b). A summary and conclusions are outlined in the last section
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