Fire managers, climate scientists join forces in planning for severe wildfire hazard in U.S. Southeast and Southwest

Lori Stiles
Feb. 25, 2000

Thomas W. Swetnam, 520-621-2112,
Jonathan T. Overpeck, 520-622-9065,

TUCSON, ARIZ. -- Concern over a potentially severe fire season this year sparked a first-time gathering of fire managers from across the nation with climate scientists who have recently helped uncover the linkages between La Nina and fire severity.

Participants at a climate and fire management workshop held Feb. 23 _ 24 at the University of Arizona emphasized the need for land and nature resource managers to incorporate more information on climate variability in their short- and long-term planning.

The workshop was sponsored by the Climate Assessment Project of the Southwest (CLIMAS), with funding from the National Oceanic and Atmospheric Administration, the UA Institute for the Study of Planet Earth and the UA Laboratory of Tree-Ring Research.

The climate scientists outlined how the predicted La Nina has been in full force after 20 months, and that La Nina events have historically led to drier than average conditions in the southeast and southwest regions of the United States, particularly in Florida, Arizona, New Mexico and southern Colorado.

"The state of Arizona recorded its driest October-through-January period in the last 105 years, and temperatures have been three to five degrees Fahrenheit warmer than average during the same period, " said Kelly Redmond, deputy director of the Western Regional Climate Center and regional climatologist.

As predicted almost a year ago, these regions are now indeed now very dry - including very low winter rainfall amounts at low elevations and low snow pack at higher elevations, according to workshop participants.

Historically, La Nina is correlated not only with warm and dry conditions in the southeastern and southwestern United States, but also with high incidence of wildland fires in these regions. The higher-than-average fire occurrence is attributed to both the anomalous dryness and warmth.

"Tree-ring fire records spanning the last 300 years in the Southwest reveal a strong relationship between wildfire occurrence and the warm/dry conditions associated with La Nina" said Thomas W. Swetnam, director of the UA Laboratory of Tree-Ring Research, and an ecologist and tree-ring scientist.

Forecasts now indicate that the warm dry conditions are likely to persist through spring, noted Jonathan T. Overpeck, director of the Institute for the Study of Planet Earth and workshop participant.

"As we go from late winter to spring, the probability of significant new rain and snow becomes smaller, but unanticipated storms like those of last year's spring could decrease fire hazard significantly," Swetnam added.

Moreover, previous wet seasons created a large stock of grasses and brush that are now being dried to exceptionally flammable levels. As a consequence of the anomalous climate and fuels all indicators point to a very active fire season in the U.S. southeastern and southwestern regions. Wildfires have already started in southern Florida and New Mexico, Overpeck also noted..

"The Coronado National Forest has already managed 18 wildfires since November - an abnormally high number for this time of the year," said Ted Moore of the Fire Management Office, Catalina District, U.S. Forest Service. "Many of these fires were at high elevations in the mountains normally covered by deep snow this time of the year."

As a start, the forest managers and climate scientists plan to work closely this fire season, and also to lay the groundwork for an improved national fire management system.

"The acceptance of this new climate prediction paradigm by the people who have to manage the forests is superb," said James O'Brien, director of the Center for Ocean-Atmosphere Prediction Studies and director of the Southeast Climate Assessment Project.

"This meeting was extremely valuable in identifying ways to anticipate increased fire hazards and to request the additional fire management resources needed to reduce the heightened threats to state, federal and private lands," Moore added.

"But, the bottom line is that all visitors to the very dry forests and range lands this year need to take extra caution to prevent wildfire."


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