Widespread Wildfires Over the Western United States in 2020 Linked to Emissions Reductions During COVID‐19. Issue 15 (5th August 2022)

• Record Type: Journal Article
• Authors: Ren, Lili; Yang, Yang; Wang, Hailong; Wang, Pinya; Yue, Xu; Liao, Hong
• Is Part Of: Geophysical research letters. Volume 49:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-05
• Subjects: wildfire -- United States -- emissions reduction -- COVID‐19 -- aerosol -- greenhouse gases; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2022GL099308
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Widespread wildfires struck the western United States in 2020, damaging properties and threating human lives. Meanwhile, the COVID‐19 pandemic spread across the globe, which disrupted human activities. Here, we investigate the effects of the emissions reductions during the pandemic on fire weather in 2020 over the western United States by using an earth system model together with observations. We show that reductions in aerosols dominate the increases in wildfire risks, whereas greenhouse gas decrease counteracts this influence. The aerosol emissions reductions increased surface air temperature and decreased precipitation and relative humidity due to a weakened moisture transport, which explains one‐third of the observed increase in wildfire risks during August–November over the western United States in 2020. This study suggests that COVID‐19‐related emissions reductions have an unexpected influence on wildfires, highlighting a different but important role of human activities in affecting wildfire risks. Plain Language Summary: Widespread wildfires struck the western United States in 2020 and caused devastating damage on the environment and society. Due to the COVID‐19 pandemic, human activities were restricted and resulted in reductions in anthropogenic emissions. Based on climate model and observational data, our results show that the COVID‐19 emissions reductions in particular matter increased surface air temperature and decreased precipitation and relative humidity, which explains one‐third of the observed increase in the risk of wildfires over the western United States in 2020. Key Points: The impacts of COVID‐19 emissions reductions on weather conditions for wildfire over the western United States in 2020 were investigated The COVID‐19 emissions reductions increased surface air temperature and decreased precipitation and relative humidity Reductions in aerosols explain one‐third of the observed wildfire risk increase, whereas greenhouse gas decrease counteracts this influence