In the researchers' simulations, years with no large fires very common in the recent past become extremely rare by 2050 and are all but eliminated after 2050. The projections show that after 2050, the average annual area burned is about 100,000 hectares, or nearly 400 square miles. By 2075, the average yearly burn exceeds that of the historic season of 1988, when fires claimed more than 1,200 square miles.
Westerling cautioned, though, that the models used in the study will not work once the increase in fires creates a fundamental change in the ecosystem. As the landscape changes, the relationships between climate and fire would change as well.
"The biggest challenge for us is to understand what can happen when the ecosystem is transformed," Westerling said. "Our projections also depend on the climate models we are using for example, if projections for winter snow pack or summer rainfall were to increase significantly, that would change our results."
Westerling and his coauthors said warming alone is likely to lead to a decline in suitable habitat for tree species currently found in greater Yellowstone, and the projected increase in frequency and severity of wildfires could accelerate that process to a tipping point at which the trees may no longer regenerate. This could cause some forested areas to be converted to woodland or non-forest, and similar changes might be expected in other subalpine or boreal forests.
"The climatic conditions projected for the second half of this century are similar to what we see in areas of the west today that have different forest types from Yellowstone's," Westerling said. "We don't know how fast those species will migrate in response to climate change, though, so
|Contact: James Leonard|
University of California - Merced