Examining trends in multiple parameters of seasonally‐relative extreme temperature and dew point events across North America

Abstract

Concurrent with the background rise in global mean temperatures, changes in extreme events are also becoming evident, and are arguably more impactful on society. This research examines trends in three components of seasonallyrelative extreme temperature and humidity events in North America that directly influence human thermal comfort: event frequency, duration, and areal extent. Results indicate that for the majority of the study domain, changes in these events are in the expected direction with changes in means. Extreme heat events are generally increasing throughout the domain, with the largest changes in summer and autumn in the eastern portion of Canada and the United States. Cold events are largely decreasing in these same locations and seasons, with additional widespread decreases in winter. Interestingly, significant increases in cold events are also evident in autumn in parts of the western United States. Extreme humidity events are showing an even greater change than temperature eventsnearly all of Canada and most of the United States is seeing significant increases in extreme humid events and decreases in dry events, while the southwestern deserts show widespread significant increases in dry events, especially in winter and spring. Changes in event duration and spatial extent mimic these results. Importantly, this research demonstrates that there are regions that show changes to extreme events that differ from the overall changes in means, highlighting the importance of looking beyond climate averages to examine not only extreme events, but changes in higher-order statistical moments. K E Y W O R D S climate change, extreme events, North America, statistical moments, trends 1 | INTRODUCTION The evaluation of climate changes, both observed and projected, has most frequently focused on the analysis of mean fields (e.g., IPCC report, Hartmann et al., 2013). Considering their relative infrequency, however, extreme weather events have a disproportionately greater impact on many biological systems (e.g., human health, agriculture, ecosystems) in comparison to climatic averages, yet are less-often studied and deserve more detailed analyses.

Global trends in atmospheric layer thickness since 1940 and relationships with tropical and extratropical climate forcing

“…This metric provides insights into the vertical structure of the atmosphere, essential for understanding the overall atmospheric dynamics. Hence while prior studies have documented that global temperature is rising and there are a wide variety of associated indicators of this change, along with potential impacts [16][17][18][19], this study applied ERA5 reanalysis data to examine how global atmospheric layer thickness has changed since 1940.…”

Weather whiplash: Trends in rapid temperature changes in a warming climate

“…While no validation on station-based observations was undertaken specifically for the research described herein, prior research has shown reanalysis temperature data to associate well with observed stationbased data. For example, Lee et al (2021) found that temperature trends in the North American Regional Reanalysisan older-generation reanalysis than ERA5were only significantly different in $2% of locations examined. And, Sheridan et al (2020) found that extreme temperature days from ERA-5 data matched observations 80% of the time over the United States and Canadawith some areas exhibiting >98% accuracybetter than any of the other reanalyses examined.…”

“…For example, Lee et al . (2021) found that temperature trends in the North American Regional Reanalysis – an older‐generation reanalysis than ERA5 – were only significantly different in ~2% of locations examined. And, Sheridan et al .…”

“…In particular, in the United States, some recent media reports of cold‐season weather shifts have labelled the phenomenon “winter whiplash” or “weather whiplash” (Cohen, 2016; Casson et al ., 2019; Harvey, 2019; CBS, 2020; Ma and Zhu, 2021). While most of the attention on climate change focuses on trends in climatological means, recent research highlights the need to expand the breadth of impacts research to include more detailed analyses of other statistical parameters (Lee et al ., 2021). Moreover, with increasing public attention to the issue of global climate change (Marlon et al ., 2020), the question of whether climate change is impacting the frequency or severity of these whiplash events has been posed to the author of this research more than once.…”

Recent Climatology (1991–2020) and Trends in Local Warm and Cold Season Extreme Temperature Days and Nights in Arabia

“…Knowledge regarding different aspects of ETEs and any changes or variability is beneficial for many sectors, including health and the environment. For example, a comprehensive analysis and understanding of the temporal behaviors of temperature extremes is a critical component in the development of effective early warning systems [ 29 ], planning for resilient public health systems [ 30 ], and strategies for ETE mitigation and adaptation [ 21 ]. This study aims to update the knowledge on ETEs in Arabia using an extreme temperature seasonal definition that considers both spatial and temporal differences.…”