Impact of California wildfires on climate, forests

The impact of California's wildfires on climate and forests is one of the most important issues of our time. This is a new era with a new federal administration, a new Congress, a new political and economic landscape, and new opportunities.

The fact is that the wildfire crisis is becoming more serious each year.

Fires are getting bigger, more destructive and more expensive. In 2001, California wildfires burned 500,000 acres. More than 1 million acres burned in 2007 and again in 2008, the worst fire year in the state's history. Next year could be even worse.

From 2001 to 2007, fires burned more than 4 million acres and released an estimated 277 million tons of greenhouse gases into the atmosphere from combustion and the post-fire decay of dead trees. That is an average of 68 tons per acre.

These wildfires kill wildlife, pollute the air and water, and the greenhouse gases they emit are wiping out much of what is being achieved to reduce emissions from fossil fuels to battle global warming.

These emissions are equivalent to adding an estimated 50 million more cars onto California's highways for one year, each spewing tons of greenhouse gases. Stated another way, this means all 14 million cars in California would have to be locked in a garage for three and one-half years to make up for the global warming impact of these wildfires.

The catastrophic and unnatural forest fires that ravage California each year do not resemble historic fires. Frequent lightning and Native American-set fires that burned along the ground, igniting only scattered small groups of trees, kept forests open and healthy, and resistant to catastrophic fires.

Even chaparral fires in the vast brushlands of Southern California were limited in extent in past centuries. Frequent fires sustained a mosaic in which old flammable chaparral was isolated between patches of less flammable young chaparral, which kept wildfires from spreading across the landscape, regardless of strong winds.

An industrialized and modern world cannot live with the annual recurrence of unnatural catastrophic wildfires. That is not realistic or acceptable. The only solution is to protect our communities, forests and climate by reducing the threat of wildfires.

That means not just fighting fires but taking action to reduce fuels to prevent fires.

There is no question that thinning large and small trees is effective in helping prevent crown fires, as documented in two California wildfires - the Cone Fire in 2002 and the Bell Fire in 2005 - when they dropped to the ground and became light, and easily suppressed surface fires after entering thinned forests.

Unfortunately, hundreds of millions of dollars are spent fighting wildfires each year and very little is spent on fuel reduction. It is no wonder that wildfires are getting bigger and more destructive since forests keep growing thicker and fuel piles up.

Some California forests have more than 1,000 trees per acre when 40 to 60 trees per acre would be natural. These dense forests contain small trees that can carry fire into the canopy, and heavy concentrations of woody debris on the ground that intensify the flames. This combination of too many large trees intermixed with small trees and surface debris are responsible for the size and severity of forest fires.

This is only part of the wildfire tragedy.

Wildfires are causing California's forests to dwindle and the greenhouse gases they

emitted will stay in the atmosphere for centuries. This means that the estimated 134 million tons of carbon dioxide (CO2) released by fires and the decay of dead trees from forests that were permanently converted to brush will continue to worsen global warming. Harvesting dead trees, storing the carbon they contain in wood products, and planting a young forest that absorbs CO2 through photosynthesis is the only way to recover this greenhouse gas from deforested areas.

The immensity of greenhouse gas emissions from California's wildfires and the permanent loss of huge areas of forest are a warning.

If we take these steps, we can restore the natural health and diversity of our forests, help the fight to reduce harmful emissions, and leave a legacy of which we can be proud.

Thomas Bonnicksen is professor emeritus of forestry from Texas A&M University, visiting scholar with The Forest Foundation and research scholar in residence at Cal Poly San Luis Obispo. This piece is based on an upcoming report, "Impacts of California Wildfires on Climate and Forests: A Study of Seven Years of Wildfires: 2001-2007."