How Unexpected Was the 2021 Pacific Northwest Heatwave?

Abstract The 2021 Pacific Northwest heatwave featured record‐smashing high temperatures, raising questions about whether extremes are changing faster than the mean, and challenging our ability to estimate the probability of the event. Here, we identify and draw on the strong relationship between the...

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Main Authors: Karen A. McKinnon, Isla R. Simpson
Format: Article
Language:English
Published: Wiley 2022-09-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2022GL100380
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author Karen A. McKinnon
Isla R. Simpson
author_facet Karen A. McKinnon
Isla R. Simpson
author_sort Karen A. McKinnon
collection DOAJ
description Abstract The 2021 Pacific Northwest heatwave featured record‐smashing high temperatures, raising questions about whether extremes are changing faster than the mean, and challenging our ability to estimate the probability of the event. Here, we identify and draw on the strong relationship between the climatological higher‐order statistics of temperature (skewness and kurtosis) and the magnitude of extreme events to quantify the likelihood of comparable events using a large climate model ensemble (Community Earth System Model version 2 Large Ensemble [CESM2‐LE]). In general, CESM2 can simulate temperature anomalies as extreme as those observed in 2021, but they are rare: temperature anomalies that exceed 4.5σ occur with an approximate frequency of one in a hundred thousand years. The historical data does not indicate that the upper tail of temperature is warming faster than the mean; however, future projections for locations with similar climatological moments to the Pacific Northwest do show significant positive trends in the probability of the most extreme events.
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spelling doaj-art-ecdc2f86154f4bbe9cfef130682b712d2025-08-20T02:10:39ZengWileyGeophysical Research Letters0094-82761944-80072022-09-014918n/an/a10.1029/2022GL100380How Unexpected Was the 2021 Pacific Northwest Heatwave?Karen A. McKinnon0Isla R. Simpson1Departments of Statistics and Atmospheric and Oceanic Sciences Institute of the Environment and Sustainability University of California Los Angeles CA USANational Center for Atmospheric Research Boulder CO USAAbstract The 2021 Pacific Northwest heatwave featured record‐smashing high temperatures, raising questions about whether extremes are changing faster than the mean, and challenging our ability to estimate the probability of the event. Here, we identify and draw on the strong relationship between the climatological higher‐order statistics of temperature (skewness and kurtosis) and the magnitude of extreme events to quantify the likelihood of comparable events using a large climate model ensemble (Community Earth System Model version 2 Large Ensemble [CESM2‐LE]). In general, CESM2 can simulate temperature anomalies as extreme as those observed in 2021, but they are rare: temperature anomalies that exceed 4.5σ occur with an approximate frequency of one in a hundred thousand years. The historical data does not indicate that the upper tail of temperature is warming faster than the mean; however, future projections for locations with similar climatological moments to the Pacific Northwest do show significant positive trends in the probability of the most extreme events.https://doi.org/10.1029/2022GL100380heatwavesclimate changenon‐normalityextreme eventsPacific Northwest
spellingShingle Karen A. McKinnon
Isla R. Simpson
How Unexpected Was the 2021 Pacific Northwest Heatwave?
Geophysical Research Letters
heatwaves
climate change
non‐normality
extreme events
Pacific Northwest
title How Unexpected Was the 2021 Pacific Northwest Heatwave?
title_full How Unexpected Was the 2021 Pacific Northwest Heatwave?
title_fullStr How Unexpected Was the 2021 Pacific Northwest Heatwave?
title_full_unstemmed How Unexpected Was the 2021 Pacific Northwest Heatwave?
title_short How Unexpected Was the 2021 Pacific Northwest Heatwave?
title_sort how unexpected was the 2021 pacific northwest heatwave
topic heatwaves
climate change
non‐normality
extreme events
Pacific Northwest
url https://doi.org/10.1029/2022GL100380
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