Forest Fires Cool Northern Climates

Forest fires in northern countries may cause regional cooling and not warming, as was previously thought. Researchers say their new findings could mean that on a global scale, forest fires will not affect climate change one way or the other.

Unusually large fires have blazed across Canada, Alaska, Russia, Norway, Sweden and other northern countries over the past decade. Researchers have said that warmer climates, longer summers and generally drier conditions may be increasing their frequency.

It was thought releasing the large amounts of carbon dioxide stored in trees would mean that forest fires would contribute to the greenhouse effect and start a fiery feedback loop. Not so, says a team of 17 US and Australian researchers in Science.

The team took an overall look at the effects of a forest fire that burned about 6.7 hectares (16.5 acres) of the Donnely Flats in central Alaska in June 1999. Some researchers looked changes in how the area reflected radiation from the sun, while others looked at greenhouse gas emissions and changes in vegetation.

They then plugged all their data into a computer model and projected it 80 years forward to see how a single fire would affect climate in the short and medium term.

They found that while temperatures did warm for about one year after the fire, this was reversed within 10 to 15 years. Averaged over 80 years, the overall effect was a cooling of temperatures.