June 26, 2012

The Fire Next Time

The Waldo Canyon fire raging on the western edge of  Colorado Springs has riveted my attention in the last few days. It is but one of many in Colorado this year, though uncomfortably close to yours truly, and right next door to the home of a close friend. One question unasked in the non-stop local media coverage is the effect of climate change on fire-prone regions, a topic explored in a recent study by researchers at UC Berkeley and Texas Tech.  The following extract, from a piece by Nathanael Massey at Climate Wire, gives the unnerving details. 

Although no single fire, no matter how severe, can be concretely linked to global climate change, the climatic conditions seen in Colorado this year fit the kind of pattern scientists expect to see in the future.

In one of the most comprehensive fire-modeling studies to date, researchers from the University of California, Berkeley, and Texas Tech University aggregated 16 separate climate models to map future fire-prone regions of the globe.

Their findings suggest that, in the decades to come, fire prevalence will decrease in tropical regions -- but will increase, possibly severely, at more northerly latitudes, and particularly in the western United States.

"In next 30 years, we're looking at pretty consistent disruption of current fire patterns for over half the planet -- most of which involve increases" in severity, said lead author Max Moritz, a fire specialist based at UC Berkeley's College of Natural Resources.

Toward the end of the century, he said, an increased prevalence of fire becomes a near certainty for most of the Northern Hemisphere.

Modeling future climate scenarios is a notoriously tricky science, involving wide margins of uncertainty, myriad variables and a profusion of data. To improve accuracy, Moritz's team looked for commonalities among 16 models and produced their own projections of the results.

With this new, aggregate climate map in hand, they turned to a technique used primarily by ecologists and biologists, called species distribution modeling, to identify fire-prone regions of the globe.

When modelers want to predict the future movement of a particular species, they first establish a set of conditions -- in terms of climate, soil quality and other variables -- under which that species is likely to thrive. Examining future climate projections over a large area, they can identify regions where such conditions are likely to arise, drawing the species to them as they do so.

The researchers realized they could apply the same science to fire. "Basically, we looked at fire as an organism," said Moritz. "We asked ourselves, 'What are its habitat requirements? What are the conditions under which fire's going to thrive?'"

Fire prevalence would intensify in regions characterized by two factors, they decided -- an abundance of fuel and long, dry summers. They looked to their models to determine where this "perfect storm" might come together and found that, by the end of the century, almost all of North America and most of Europe would likely see a jump in the frequency of wildfires.

Tropical regions, despite holding an abundance of fuel, would see their dry season decline, lessening their chances for severe burns.

Given those trends, human beings will need to adjust their approach to fire management, said Moritz.

Fire has always been an integral part of the ecology of the western United States, a force of destruction but also of renewal. Periodic wildfires clear old growth, curb beetle kill and even aid in the propagation of certain plant species whose seeds can be released only under extreme heat.

Humans, on the other hand, have generally opted to obstruct the cycle rather than coexist with it. And that has had some unintended consequences.

Fire suppression throughout much of the 20th century allowed fuel to accumulate, leading to a sharp uptick in severe, extensive burns in the 1980s and 1990s.

Since then, forest managers have begun to adopt "controlled burn" regimes, in which fires are intentionally set in areas judged to need them.

If Moritz's projections are correct, however, efforts to control seasonal fires -- through both suppression and pre-emption -- will need to be scaled up in tandem with increased fire prevalence.

Those efforts are progressing, if slowly. The U.S. Forest Service announced yesterday that it has contracted for seven new "next generation" air tankers for wildfire suppression, part of the service's ongoing efforts to replace its current, aging fleet.

Nathanael Massey, “As Wildfires Rage in U.S. West, Scientists Predict Worse Blazes in Future,” Climate Wire, June 14, 2012, via Scientific American.

The above image is from krdo.com, the website of a Colorado Springs TV station.