Wildfires: A sign of Climate alteration

This summer, wildfires swept across some 22 regions of Russia, blanketing the country with thick smoke and in some cases destroying entire villages. In the foothills of Boulder, Colo., this month, wildfires exacted a similar toll on a smaller scale.

That's just the tip of the iceberg. Thousands of wildfires big and small are in progress at any given time across the globe. Beyond the obvious immediate health effects, this "biomass" burning is part of the equation for global warming. In northern latitudes, wildfires actually are a symptom of the Earth's warming. 'We already see the initial signs of climate change, and fires are part of it," said Dr. Amber Soja, a biomass burning expert at the National Institute of Aerospace (NIA) in Hampton, Va. And research suggests that a hotter Earth resulting from global warming will lead to more frequent and larger fires. The fires release "particulates" -- tiny particles that become airborne -- and greenhouse gases that warm the planet.

Human ignition

A 2008 fire sparked by logging equipment in the Great Dismal Swamp National Wildlife Refuge in Suffolk, Va., lasted 121 days and cost $12 million dollars. It was the longest and most expensive wildfire in Virginia history. Credit: U.S. Fish and Wildlife Service What is 'biomass burning'? It's the burning of living and dead vegetation. It includes human-induced burning as well as naturally occurring fires.

Where it happens most:
•Boreal forests in Alaska, Canada, Russia, China, Scandinavia

•Savannah grasslands in Africa •Tropical forests in Brazil, Indonesia, Colombia, Ivory Coast, Thailand, Laos, Nigeria, Phillipines, Burma, Peru

•Temperate forests in U.S., Europe

•Agricultural waste after harvests in U.S., Europe

A common perception is that most wildfires are caused by acts of nature, such as lightning.