Although rising global temperatures could lead to much drier trees and forests around the world, that may not necessarily translate to an increased risk for wildfires, according to a new study in this month's issue of Ecological Monographs.
This somewhat contradicts other recent research, most of which has identified a link between global warming and the increasing likelihood of wildfires, including studies from Science in 2006 (Study links extended wildfire seasons to global warming) as well as the Intergovernmental Panel on Climate Change in 2007 (Is Earth near its 'tipping points' from global warming?).
These studies indicated that wildfires in many parts of the world will increase over the next century as climate change lengthens the fire season, decreases moisture and increases ignition rates.
In this month's study, however, scientists found that changes in vegetation trumped past climate changes in determining wildfire frequency, based on research into Alaskan forests. For example, although the researchers discovered a transition from a cool, dry climate to a warm, dry climate some 10,500 years ago in Alaska, wildfires actually declined at that time because of a vegetation change from flammable shrubs to fire-resistant deciduous trees.
The research team analyzed historical fire occurrence by studying sediments found in the bottom of lakes.
"There's a complex relationship between fuels and climate," said study author Tom Brown of the Lawrence Livermore National Laboratory in Livermore, Calif. "Vegetation can have a profound impact on fire occurrences that are opposite or independent of climate's direct influence on fire.
" If all we did was look at rising temperatures and ignore the vegetation in the area," he added, "that wouldn't be a good predictor of the likelihood of wildfires in a particular region."
Other scientists involved in the research were from Montana State University, the University of Washington, and the Universtiy of Illinois-Urbana.