An additional 16,000 square miles — larger than the states of Massachusetts and Connecticut combined — burned in forest fires since 1984 due to climate change, nearly double the area that would have burned otherwise, says a study in the journal Proceedings of the National Academy of Sciences. “No matter how hard we try, the fires are going to keep getting bigger and the reason [rising temperatures] is really clear,” said bioclimatologist Park Williams, a co-author of the study.
Warmer weather drives fire by drying out trees, grasses and soil, say the researchers, and average temperatures in forested parts of the West have risen 2.5 degrees F since 1970, “and are expected to keep rising,” says a Columbia University release. The study did not cover western grasslands. Some three million acres, or nearly 4,700 square miles, were hit by forest fires this year in the United States, mostly in the West.
Lead author John Abatzoglou, a geology professor at the University of Idaho, said researchers “wanted to put some numbers” to the speculation about the impact of climate change. The study said the overall increase in fires since the 1980s is twice the figure that the study attributed to climate change. The other factors include an long-running natural climate oscillation that has steered precipitation away from the western states. Researchers used eight different ways to rate forest aridity in order to isolate the effects of climate change.