Doubling of U.S. Population Exposure to Climate Extremes by 2050

Abstract

We quantify historical and projected trends in the population exposure to climate extremes as measured by the United States National Center for Environmental Information Climate Extremes Index (CEI). Based on the analyses of the historical observations, we find that the U.S. has already experienced a rise in the occurrence of aggregated extremes in recent decades, consistent with the climate response to historical increases in radiative forcing. Additionally, we find that exposure can be expected to intensify under the Representative Concentration Pathway 8.5, with all counties permanently exceeding the baseline variability in the occurrence of extreme hot days, warm nights, and drought conditions by 2050. As a result, every county in the U.S. is projected to permanently exceed the historical CEI variability (as measured by one standard deviation during the 1981-2005 period). Based on the current population distribution, this unprecedented change implies a yearly exposure to extreme conditions for one in every three people. We find that the increasing trend in exposure to the aggregated extremes is already detectable over much of the U.S., and particularly in the central and eastern U.S. The high correspondence between the pattern of trends in our simulations and observations increases confidence in the projected amplification of population exposure to unprecedented combinations of extreme climate conditions, should greenhouse gas concentrations continue to escalate along their current trajectory.

Chronic Mental Health Sequelae of Climate Change Extremes: A Case Study of the Deadliest Californian Wildfire

“…Weather extremes driven by climate change, such as the California wildfires, are associated with huge costs to human health [ 9 , 10 , 11 ]. It is projected that the US population exposed to such climate extremes will nearly double by 2050, affecting nearly 25% of all humans in the US each year [ 12 ].…”

“…Such disasters could expose specific vulnerabilities and mental health outcomes that may be unique to climate change-driven events and not to routine natural disasters. The main distinction between naturally occurring weather disasters from those amplified by unchecked anthropogenic climate change is that weather disasters forced by climate change will progressively get worse [ 12 ].…”

Shift Toward Intense and Widespread Precipitation Events Over the United States by Mid‐21st Century

“…Studies that investigate the changes in the precipitation characteristics mainly focus on event intensity and/or frequency (Bishop, Williams, & Seager, 2019; Bishop, Williams, Seager, Fiore, et al, 2019; Donat, Alexander, et al, 2016; Donat, Lowry, et al, 2016; Hoerling et al, 2016) and not spatial characteristics. To this end, an amplification in the occurrence and the strength of intense precipitation events over the past century has been noted by many studies (Dittus et al, 2015; Donat, Alexander, et al, 2016; Fischer & Knutti, 2016; Huang et al, 2018; Karl & Knight, 1998), which is projected to further exacerbate in response to an increase in radiative forcing (Batibeniz et al, 2020; Donat, Lowry, et al, 2016; Rastogi, 2017). The projected intensification of precipitation events is attributed to the fact that a warmer atmosphere holds more moisture, following the Clausius‐Clapeyron relationship (C‐C scaling; 6.0–7.5% per °C), which leads to higher amounts of precipitable water (Min et al, 2011; Rastogi et al, 2020; Roderick et al, 2019; Santer, 2007; Willett et al, 2007).…”

Anthropogenic Warming and Population Growth May Double US Heat Stress by the Late 21st Century

“…Generalized extreme value (GEV) approaches have gained increasing popularity in this context (Ouarda & Charron, 2018; Raymond et al., 2020). Common approaches to quantify risk of exposure are based on counting the number of people exposed to certain heat events under stationarity assumptions (Batibeniz et al., 2020; Jones et al., 2015; Matthews et al., 2017; Mazdiyasni et al., 2017; Mishra et al., 2017). This type of risk assessment potentially ignores the effects of non‐stationarity as expressed in the form of statistical distributions for the relevant climate variables with time‐dependent heavy tailedness.…”