Climate change lengthens southeastern USA lightning-ignited fire seasons

Area of Science:

• Environmental Science
• Climate Science
• Forestry

Background:

• Detecting changes in climatic fire seasons requires more than just precipitation trends, especially in regions with wet-dry cycles and lightning activity.
• The southeastern United States Coastal Plain experiences fire seasons influenced by seasonal precipitation and lightning.

Purpose of the Study:

• To examine changes in dry season length, total precipitation, and thunder-day distribution in the southeastern US Coastal Plain from 1897 to 2017.
• To assess the influence of altered climatic seasonal parameters on fire regimes.

Main Methods:

• Analysis of an extensive dataset spanning 120 years (1897-2017).
• Examination of annual dry season length, total precipitation, and seasonal thunder-day distribution (since 1945) as a proxy for lightning activity.

Main Results:

• The dry season in the region has significantly lengthened, by up to 156 days (130% increase over 120 years).
• The dry season is starting earlier and ending later, accompanied by a reduction in total precipitation.
• No significant change was observed in seasonal thunderstorm patterns.

Conclusions:

• Reduced rainfall over an extended dry season, without changes in thunderstorm frequency, likely elevates the risk and severity of lightning-ignited wildfires.
• Global climate change may be subtly influencing fire regimes by disrupting the synchrony of climatic seasonal parameters.