Unprecedented 21st century heat across the Pacific Northwest of North America

Karen J. Heeter, Grant L. Harley, John T. Abatzoglou, Kevin J. Anchukaitis, Edward R. Cook, Bethany L. Coulthard, Laura A. Dye, Inga K. Homfeld

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Extreme summer temperatures are increasingly common across the Northern Hemisphere and inflict severe socioeconomic and biological consequences. In summer 2021, the Pacific Northwest region of North America (PNW) experienced a 2-week-long extreme heatwave, which contributed to record-breaking summer temperatures. Here, we use tree-ring records to show that summer temperatures in 2021, as well as the rate of summertime warming during the last several decades, are unprecedented within the context of the last millennium for the PNW. In the absence of committed efforts to curtail anthropogenic emissions below intermediate levels (SSP2–4.5), climate model projections indicate a rapidly increasing risk of the PNW regularly experiencing 2021-like extreme summer temperatures, with a 50% chance of yearly occurrence by 2050. The 2021 summer temperatures experienced across the PNW provide a benchmark and impetus for communities in historically temperate climates to account for extreme heat-related impacts in climate change adaptation strategies.

Original languageEnglish (US)
Article number5
Journalnpj Climate and Atmospheric Science
Issue number1
StatePublished - Dec 2023

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Atmospheric Science


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