Wildfires more likely in warming world

A warming climate could lead to a spike in wildfires, according to a study Monday that researched the history of brush blazes in the Rocky Mountains.

Researchers examined charcoal deposits in 12 lakes in northern Colorado and found evidence that "wildfires burned large portions of that area during a documented spike in temperatures in North America starting about 1,000 years ago," said the study.

The 300-year period of unusual warmth and drought is known as the Medieval Warm Period (MWP), when temperatures rose just under 1 degree Fahrenheit (0.5 Celsius).

The study focused on an area of 385 square miles (100,000 hectares).

In that zone, "wildfire frequency was 260 percent greater than during the past 420 years," said the study.

"The results suggest a link between a warming climate and increased wildfire frequency, and that wildfires may become more frequent if temperatures continue to rise."

The climate warmed 0.9 degrees Fahrenheit during the medieval warming period.

By comparison, the average increase in temperature in the Rocky Mountain region since the year 2000 has been about 1.25 degrees Fahrenheit higher than during the 20th century, according to the study.

The majority of scientists agree that the current warming trend is driven by modern industrialization and the burning of fossil fuels which trap heat in the atmosphere.

Large wildfires have raged in the midwest with increasing frequency since the mid 1980s, according to the study.

"What our research shows is that even modest regional warming trends, like we are currently experiencing, can cause exceptionally large areas in the Rockies to be burned by wildfires," said study author John Calder, a doctoral student at the University of Washington.

"When we look back in time, we only see evidence of large areas burning one time in the last 2,000 years," Calder added.

"This suggests that large wildfires of the magnitude we have recently seen used to be very infrequent."

The study is published in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.