As climate change reduces snowpack in spring months, forest-clearing fires could expose more sun-absorbing ground instead of reflective snow, increasing local and regional warming, according to a new study published in Global Change Biology. Researchers warn the warming effect could be as much as 15-28% regionally, but also believe that the data could help inform future fire management.
The climate impact of boreal fires was first documented in a landmark 2006 study. Boreal forest fires increase warming on a global scale by releasing greenhouse gasses and depositing black carbon on snow and ice, but actually cool the local landscape because of increased albedo, or surface reflectivity. After trees burn, underlying snowpack in the winter and spring becomes exposed, which increases the amount of sunlight that gets reflected back to space and causes regional cooling.
“We estimate climate change will lead to a reduction in the cooling effect from long-term post-fire albedo by 15-28%. For northern regions like Alaska that are already warming faster than the rest of Earth, this will intensify heat waves, fires, and permafrost thaw,” said WHRC scientist Stefano Potter.
While previous studies have relied solely on observations, researchers for this study used a novel machine learning modeling framework to predict fire-driven changes in albedo under historical and future climate scenarios across boreal North America. This model suggests that climate change will reduce snow cover in the spring months, leading to less reflectivity and more absorption of solar energy after fire events. In other words, the local cooling impact of these boreal fires will not be as strong in future climates.
“We’re finding that climate change will decrease the local-to-regional cooling impact from these boreal forest fires. That’s bad news. The good news is that we’re anticipating our research can be used by fire managers to make decisions about firefighting priorities and resources, deciding which fires to suppress and which to let burn. Climate impacts are not currently accounted for, but could be given proper funding and policy frameworks,” said WHRC scientist Dr. Brendan Rogers.
This study was conducted with support from NASA ABoVE.
Date of publication: 20 Nov 2019
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