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Posted at 11:55 AM ET, 06/13/2012

Southwest drought, climate warming and fuel: an explosive combination for record wildfires


Smoke billows from a wildfire burning west of Fort Collins, Colo., on Tuesday, June 12, 2012. The fire which started on Saturday has burned more than 40,000 acres and one person is dead as it continues to burn out of control. (V. Richard Haro - AP)

(Correction, 6/14/2012, 9:30 a.m.: the NPR report mentioned below, indicating the Colorado High Park fire is the second largest on record appears to be erroneous; the Denver Post and other sources indicate it is the 3rd largest on record, having now burned about 47,000 acres)

During the last two summers, wildfires have run rampant in the Southwest, setting record after record for size and destructiveness. It’s no coincidence that severe drought and much above normal temperatures have been occurring in these same areas - although land-management practices and a surplus of combustible material - bear some responsibility as well.

Consider all of these wildfire records set in 2011 and 2012:

Texas: Suffered its worst wildfire season on record in 2011, with 30,457 fires which engulfed nearly 4 million acres (the most in a quarter century of records). The Bastrop Fire was the most destructive in Texas history, destroying more than 1,500 homes.


Satellite image of smoke from the Colorado High Park fire on June 11 ( CIMSS Satellite Blog )
New Mexico: Has had its two largest fires in state history the last two summers.The Las Conchas Fire of 2011 scorched more than 150,000 acres setting a record for largest wildfire only to be blown away in 2012 by the Whitewater-Baldy Fire Complex which has burned more than 278,000 acres (now 37 percent contained).

Arizona: The Wallow Fire in 2011 consumed more than 500,000 acres, the largest on record in that state.

Colorado: NPR reports “the High Park Fire that sparked over the weekend has quickly grown to the second largest wildfire in that state’s history”. This fire has burned more than 41,000 acres and “there’s no end in sight,” NPR said.

Now let’s examine what’s happening with the climate in this region...


U.S. Drought Monitor as of June 5
The U.S. Drought Monitor shows much of Texas, New Mexico, Colorado, and Arizona under drought conditions ranging from moderate to exceptional.

In this same region, temperatures have warmed substantially since 1970. In fact, in the Climate Central report released Tuesday, all four of these states rank among the top 20 fastest warming since 1970. Arizona is #1, New Mexico #6, Texas #9, and Colorado #20. These states have been warming at a rate of about 0.5-0.6 degrees F per decade.

In 2011, Texas had both its hottest and driest summer on record. New Mexico‘s summer also ranked as the hottest, and second driest. Arizona’s conditions weren’t as extreme, but still quite warm and dry with its 12th hottest and 27th driest summer on record.


Temperature and precipitation ranks during the summer of 2011. Record warm and dry conditions occurred over Texas and parts of the Southwest. View big. (NOAA)
In 2012, preceding the present brutal wildfire season, Colorado had its second warmest and 4th driest spring on record. New Mexico’s spring ranked third warmest and 28th driest.

There’s no disputing hot and dry conditions are conducive to the spread of wildfires, but climate is just part of the equation.

Added fuel

The availability of combustible material - related to land management practices - has grown in many areas. The increased amount of forest fire “fuel” combined with climate conditions have created an explosive combination. As Climate Central’s Andrew Freedman explains:

...the recent Southwestern megafires stand out as unusual in the context of the past 1,500 years in that region, according to a recent study. The study found that land-management changes, such as years of fire suppression activities that stifled small fires, thereby priming forests for larger blazes, have combined with climate change to create forests that are altogether different — and which burn differently — from what existed in this area for generations.

Projections of the future

Numerous studies, including one released Tuesday, predict increases in Southwest fires due to manmade climate change from increasing greenhouse gases.

Tuesday’s study, published in journal Ecosphere, projects increases in wildfire over the western U.S. and large parts of the mid-to-high latitudes globally but decreases in the tropics. The study was unique in using 16 climate models to generate its results.


Predicted average change in fire probability for the period 2010 - 2039 (top) and 2070 - 2099 (bottom) for the average of sixteen climate models. (Journal Ecosphere)
Models were very consistent in simulating fire increases in the West.

“When many different models paint the same picture, that gives us confidence that the results of our study reflect a robust fire frequency projection for that region,” said Katharine Hayhoe, study co-author

As I discussed last year, a report from the National Academy of Sciences stated the amount of area burned each year in the West could more than triple for just a 1 degree Celsius increase in temperature. Another study projected a 54 percent increase in area burned in the West by mid-21st century compared to the late 20th century.

While existing literature projects increases in wildfire activity in the West, important uncertainties in the rate and amount of change result from uncertainties in future precipitation and the amount of available fuel.

Nevertheless, the message from these studies is clear - as Max Moritz, lead-author of the Ecosphere study, put it: “We need to learn how to coexist with fire.”

By  |  11:55 AM ET, 06/13/2012

Categories:  Latest, U.S. Weather, Climate Change

 
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