Wildfires play a prominent role in the boreal forests of Alaska during the summer season. While most wildfires are created by humans, approximately 90% of the area burned each year by wildfires are caused by lightning strikes. These lightning-induced wildfires have been burning Interior Alaska for thousands of years. However, the amount of area burned from wildfires has increased in recent decades with an increased frequency of extreme years compared to when formal records first began in the 1940s. The magnitude and extremes of historical Alaskan wildfires have been linked with climate variability and anthropogenic climate change; with future climate projections anticipating increased wildfire activity for Interior Alaska over the next century. With lightning activity being a large concern for the Alaska fire weather research community, the understanding of historical drivers, variability, trends, and evaluating possible future changes in lightning activity is important to ultimately tell the story of wildfires in Alaska.
In a new Journal of Applied Meteorology and Climatology article, authors Peter Bieniek, Uma Bhatt, Alison York, John Walsh, Rick Ladder, Heidi Strader, Robert Ziel, Randi Jandt, and Richard Thoman used a dynamically downscaled reanalysis and Global Climate Model to statistically assess lightning data in geographic zones across Alaska. It was found convective precipitation was found to be a key predictor of weekly lightning activity along with atmospheric stability, moisture, and temperature predictor variables. In addition, model-derived estimates of historical June-July lightning since 1979 show an increase in lightning strikes but a shift in lower magnitude. Two downscaled Global Climate Model projections estimate a doubling of lightning activity over the June-July season and geographic region by the end of the 21st century. This increase in lightning activity may have significant impacts on future wildlife activity in Alaska.
Monthly average number of lightning strikes in each 20km grid box over 1986-2015 for (a) May, (b) June, (c) July and (d) August.
It is noted that additional studies are needed to incorporate changes in fire weather conditions, fuels, and lightning ignitions to fully capture how wildfires may evolve over the next century. This study was partially funded by the MAPP program.
Read the full paper here
The Modeling, Analysis, Predictions, and Projections (MAPP) Program is a competitive research program in NOAA Research's Climate Program Office. MAPP's mission is to enhance the Nation's and NOAA's capability to understand, predict, and project variability and long-term changes in Earth's system and mitigate human and economic impacts. To achieve its mission, MAPP supports foundational research, transition of research to applications, and engagement across other parts of NOAA, among partner agencies, and with the external research community. MAPP plays a crucial role in enabling national preparedness for extreme events like drought and longer-term climate changes. For more information, please visit www.cpo.noaa.gov/MAPP.