Wildfires to Become Bigger, Smokier and More Frequent by 2050

Wildfires will burn longer, wider and create more smoke by the year 2050, according to a new study by Harvard University researchers that brings with it some bad news for fire crews battling blazes across the western United States.

California's Rim Fire, for instance, has burned nearly 200,000 acres of forest since it ignited two weeks ago and fire crews don't expect to have the largest active wildfire in the country contained for another two weeks to come.

If predictions made by the Harvard researchers are correct, fires like the massive Rim Fire may become the new normal.

By 2050, the researchers contend that wildfires will burn three weeks longer, generate up to twice as much smoke and burn in a wider area of the western United States.

"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," said study co-author Loretta J. Mickley, a senior research fellow in atmospheric chemistry at the Harvard School of Engineering and Applied Sciences. "When you get a large temperature increase over time, as we are seeing, and little change in rainfall, fires will increase in size."

Wildfires are influenced by seasonal variables which can vary wildly depending on location. Moisture, temperature, rainfall, wind patterns, relative humidity and other variables are all able to have an effect on wildfires.

Lead author Xu Yue created an ensemble of mathematical models taking these variables into account, the outcome of which generated wildfire predictions for six "ecoregions" in the West. The multi-model ensemble increased the researcher's confidence in their results.

Among the model's findings were that, compared to today's conditions, by 2050 the area burned by wildfires in the Pacific Northwest would increase by 65 percent and could nearly double in the Eastern Rocky Mountains and Great Planes regions and quadruple in the Rocky Mountain Forest region.

The models also concluded that the possibility of large fires could increase by a factor of two or three and that the fire season will start earlier and finish later.

Mickley said that while the air quality in the US has vastly improved over the last 40 years, the predicted increase in wildfires may erase some of that progress.

"I think what people need to realize is that embedded in those curves showing the tiny temperature increases year after year are more extreme events that can be quite serious," she said. "It doesn't bode well."

The researchers' work is available online in advance of its scheduled publication in the October edition of the journal Atmospheric Environment.