Spatio-Temporal Linkages between Declining Arctic Sea-Ice Extent and Increasing Wildfire Activity in the Western United States

• Published in: Forests
• Main Authors: Paul Knapp, Peter Soulé
• Format: Text
• Language: English
• Published: Multidisciplinary Digital Publishing Institute 2017
• Subjects: Arctic sea-ice extent; western U.S. wildfire activity; Rocky Mountains; Arctic amplification; Arctic; Northern Rockies; Pacific; Sea ice
• Online Access: https://doi.org/10.3390/f8090313

We examined relationships between monthly Arctic sea-ice extent (ASIE) and annual wildfire activity for seven regions in the western United States during 1980–2015 to determine if spatio-temporal linkages exist between ASIE, upper-level flow, and surface climatic conditions conducive to western U.S. wildfire activity. Winter ASIE had significant (p < 0.05) negative relationships with annual wildfire area burned (rs = −0.391 − −0.683), with the strongest relationship occurring in the Northern Rockies. We explored spatial linkages between ASIE and 300-hPa flow (+), temperature (+), precipitation (−), and soil moisture (+) using monthly values of ASIE and gridded values for the climatic parameters. Relationships were best expressed between January ASIE and conditions in the current-year July over the Pacific Northwest and Northern Rockies. Reduced wintertime ASIE is teleconnected with increased ridging in summertime 300-hPa flow over the western U.S., resulting in warmer and drier conditions during peak fire season. Our findings suggest that reductions in ASIE are one of the driving forces behind the increasing annual trend (>36,000 ha) in area burned in the western U.S. since 1980.