I created an 8-tweet thread on Twitter on March 14, 2022, using 280-character bites to summarize our recent publication in Geophysical Research Letters, "Rapid Growth of Large Forest Fires Drives the Exponential Response of Annual Forest-Fire Area to Aridity in the Western United States". The thread is copy-pasted below.
New paper! Co-authors and I investigate why annual forest-fire area burned increases exponentially with aridity in the western United States, using a new western US wildfire database that we compiled. 1/8
As fuels dry–mainly from low precipitation and heat–the amount of annual forest area burned increases exponentially. In our study we investigate the cause of the exponential relationship. 2/8
We show: the exponential response of annual burned area to dryness is related to how individual fires spread across the landscape. Wildfires tend to grow at compounding (exponential) rates. The larger a fire, the more potential for further growth, all else (e.g., fuel) equal. 3/8
Increased aridity increases promotes fire growth when fuels are abundant. Because large fires have more potential for growth than small fires, each incremental increase in aridity leads to a much larger increase in annual forest area burned than the previous. 4/8
Thus, the exponential response of annual forest area burned to drying is driven by rapid increases in the size of the largest forest fires! Over the past nearly four decades the largest 10% of each year's fires drove 67% of the observed increase in annual forest area burned. 5/8
The extremely potent response of very large forest fires to aridification creates the potential for fire sizes and annual burned areas to easily shatter previous records. For example, 2020 & 2021 California forest area burned broke the previous modern record in 2018 by >2x. 6/8
Over the past 4 decades, <20% of western US forest area has burned. Where fuels are non-limiting and drying trends continue, we expect forest fire extents to continue increasing rapidly and shattering records. 7/8
We hope this study contributes to further research into the complex dynamics of how fire and fuels interact, and adaptation to more very large forest fires in the western US that considers sustainable decisions that benefit the environment and minimize danger to human life. 8/8
Thank you to my PhD advisor @peedublya (Park Williams) and my co-authors @climate_guy (John Abatzoglou), @DrBalch (Jennifer Balch), @MatthewHurteau (Matt Hurteau), and Max A. Moritz for all of their collaboration! And thank you to @NASA, the Zegar Family Foundation, and @NSF for funding.
Read the thread on Twitter (@caro_in_space).
Read the paper in Geophysical Research Letters.
More information and updates about my PhD research on western US wildfires.