Regional and elevational patterns of extreme heat stress change in the US

Abstract

Increasing severity of extreme heat is a hallmark of climate change. Its impacts depend on temperature but also on moisture and solar radiation, each with distinct spatial patterns and vertical profiles. Here, we consider these variables’ combined effect on extreme heat stress, as measured by the environmental stress index, using a suite of high-resolution climate simulations for historical (1980-2005) and future (2074-2099, RCP8.5) periods. We find that observed extreme heat stress drops off nearly linearly with elevation above a coastal zone, at a rate that is larger in more humid regions. Future projections indicate dramatic relative increases whereby the historical top-1% summer heat stress value may occur on about 25-50% of future summer days under the RCP8.5 scenario. Heat stress increases tend to be larger at higher latitudes and in areas of greater temperature increase, although in the southern and eastern US moisture increases are nearly as important. Imprinted on top of this dominant pattern we find secondary effects of smaller heat stress increases near ocean coastlines, notably along the Pacific coast, and larger increases in mountains, notably the Sierra Nevada and southern Appalachians. This differential warming is attributable to the greater warming of land relative to ocean, and to larger temperature increases at higher elevations outweighing larger water-vapor increases at lower elevations. All together, our results aid in furthering knowledge about drivers and characteristics that shape future extreme heat stress at scales difficult to capture in global assessments.

Subseasonal Variability of Humid Heat During the South Asian Summer Monsoon

“…In these areas, the timing of Tw extremes is more consistent with that of Tdry extremes, which have received more attention in previous literature. We also note that the strong relationship between Tw intensity and elevation, where the magnitude of mean 99th percentile Tw events declines steeply across the region’s mountain ranges (Figure 1b), is consistent with previous results identifying Tw’s dependence on elevation in the United States (Raymond et al., 2022).…”

Short Warm Distribution Tails Accelerate the Increase of Humid‐Heat Extremes Under Global Warming

“…The relative contributions of humidity and heat to the risk of human heat stress is still under active study (Lutsko, 2021). Prior research suggests that latitude, topography (Raymond et al., 2022), or other geographic and climatological factors (Buzan et al., 2015; Ivanovich et al., 2022; Raymond et al., 2017; P. Wang et al., 2019; Zhao et al., 2015) can all be influential. Buzan and Huber (2020) found that T W generally aligned with extreme humidity, but Heat Index and simple wet‐bulb globe temperature aligned with temperature.…”

A survey of blow fly (Diptera: Calliphoridae) populations in Phoenix, Arizona

“…However, understanding the temperature-colonization relationships should improve estimates of the pre-appearance interval much in the way continued studies of the temperature-development relationships of larval blow flies helps improve estimates of the TOC. Because of climate change, extreme high heat events are occurring and expected to continue to occur with increasing frequency across the desert southwestern United States (Raymond et al, 2022). While the most extreme effects may be seen in the desert, Arizona is a highly diverse state, and temperatures are rising across its deserts, mountains, rivers, and forests.…”