A view of the Yosemite Rim Fire belching smoke, via NASA's Earth Observatory
California's Yosemite National Park has been on fire for close to two weeks, and yet it's just the latest spike in a long season of burns in the western United States. Burning forests are our new normal, and they're only projected to get worse.
A growing pile of research suggests that climate change will make wildfires worse, a conclusion supported by new research published in Atmospheric Environment. Based on the research team's projections of our warming climate, the wildfire season will be around three weeks longer in 2050 and, with fires covering a larger region of western states with even more smoke than they do today.
The idea that climate change will increase wildfires seems straightforward on the surface: With wamer weather and longer droughts, brush will stay dry and flammable for longer stretches of the year. But in actuality, it's more complicated than that.
“We weren’t altogether certain what we would find when we started this project,” co-author Loretta Mickley said in a release. “In the future atmosphere we expect warmer temperatures, which are conducive to fires, but it’s not apparent what the rainfall or relative humidity will do. Warmer air can hold more water vapor, for instance, but what does this mean for fires?”
Via Yue et. al
To try to find what is a major factor in influencing wildfires, the team created two separate prediction models for the western US, which encompasses deserts, dry grasslands, and forests. One was a regression model based on meteorlogical data to predict annual area burned, and another was a model of daily burn area parameterized with temperature, precipitation, and relative humidity.
Combining the two with climate models gave the team their projected growth in fires by midcentury. According to the paper, the team calculated "increases of 24–124% in area burned using regressions and 63–169% with the parameterization, with the major driving factor being temperature.
“It turns out that, for the western United States, the biggest driver for fires in the future is temperature, and that result appears robust across models," Mickley said. "When you get a large temperature increase over time, as we are seeing, and little change in rainfall, fires will increase in size.”
Via Yue et. al
Wildfires getting larger is obviously bad news for wildlife and vegetation, as well as any human structures caught in their path, but there's another issue beyond the burns: pollution. Huge forest fires pump out huge amounts of organic and black carbon, and the research team projects that it will grow.
According to the paper, "wildfires will increase summertime surface organic carbon aerosol over the western United State by 46–70 percent and black carbon by 20–27 percent at midcentury, relative to the present day." And it gets worse during severe burns, with organic carbon and black carbon projected to increase by around 90 percent and 50 percent, respectively.
That's troublesome for anything that breathes, and it's even been found that black carbon from wildfires can help fuel climate change by increasing absorption of the Sun's rays. It's a nasty cycle, and with more researchers coming to the same predictions, one that increasingly appears to be our future.