Wildfire, drought, and insects: climate change increases risks of tree death

FORESTS FACE RISING THREATS FROM WILDFIRES, DROUGHT, AND INSECTS, WHICH COULD DRASTICALLY REDUCE THEIR CARBON SEQUESTRATION CAPACITY. ADDRESSING CLIMATE CHANGE QUICKLY COULD MITIGATE THESE

RISKS AND PRESERVE FOREST HEALTH. Planting a tree appears to be a generally positive thing to do for the environment. After all, trees take in carbon dioxide, offsetting some of the

emissions that contribute to climate change. However, all of that carbon in trees and forests worldwide could be released back into the atmosphere again if the trees burn up in a forest

fire. Trees also stop scrubbing carbon dioxide from the air when they die due to drought or insect damage. According to new research in the journal _Ecology Letters_, the likelihood of those

threats impacting forests is increasing nationwide, making relying on forests to soak up carbon emissions a much riskier prospect. “U.S. forests could look dramatically different by the end

of the century,” says William Anderegg, study lead author and associate professor in the University of Utah School of Biological Sciences. “More severe and frequent fires and disturbances

have huge impacts on our landscapes. We are likely to lose forests from some areas in the Western U.S. due to these disturbances, but much of this depends on how quickly we tackle climate

change.” WILDFIRE, DROUGHT, AND INSECTS The researchers modeled the risk of tree death from fire, climate stress (heat and/or drought), and insect damage for forests throughout the United

States, projecting how those risks might increase over the course of the 21st century. See their findings in an interactive map here. By 2099, the models found, that United States forest

fire risks may increase by between four and 14 times, depending on different carbon emissions scenarios. The risks of climate stress-related tree death and insect mortality may roughly

double over the same time. But in those same models, human actions to tackle climate change mattered enormously—reducing the severity of climate change dramatically reduced the fire,

drought, and insect-driven forest die-off. “Climate change is going to supercharge these three big disturbances in the U.S.,” Anderegg says. “We’ve seen devastating fire seasons with

increasing severity in the past several years. Generally, we expect the western U.S. to be hit hardest by all three of these. And they’re somewhat interconnected too. Really hot and dry

years, driven by climate change, tend to drive lots of fires, climate-driven tree mortality, and insect outbreaks. But we have an opportunity here too. Addressing climate change quickly can

help keep our forests and landscapes healthy.” Reference: “Future climate risks from stress, insects and fire across US forests” by William R. L. Anderegg, Oriana S. Chegwidden, Grayson

Badgley, Anna T. Trugman, Danny Cullenward, John T. Abatzoglou, Jeffrey A. Hicke, Jeremy Freeman and Joseph J. Hamman, 11 May 2022, _Ecology Letters_., DOI: 10.1111/ele.14018 The study is

published in _Ecology Letters_ and was supported by the National Science Foundation, the U.S. Department of Agriculture, David and Lucille Packard Foundation, and Microsoft’s AI for Earth.

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