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Wildfires will likely get worse in western North America

The Thomas Fire (above), which consumed 281,893 acres in California’s Santa Barbara and Ventura counties in December 2017, was the largest in the state’s history. The Nazko Complex Fire in British Columbia – which merged with other fires in August, 2017 – burned more than 1 million acres and ultimately became the largest ever recorded for the province. Image via U.S. Forest Service.

The massive wildfires that burned in California, Oregon, Montana, Idaho and British Columbia in 2017 exhibited a disturbing trend: a marked increase in the amount of area burned. While it may have been an exceptional year in some respects, new research predicts that years like 2017 are likely to become more common over time.

States in the interior western United States, in particular, may be faced with large increases in total wildfire area burned, potentially beyond anything that has been experienced in the past, according to the study, published in the journal PLOS ONE on December 15, 2017, as the 2017 fire season was ending.

The study projects where the greatest increases in area burned are likely to occur across the western U.S. and Canada in coming decades, suggesting that large fires years such as the recent ones in southern and northern California may become more common.

Projected change in annual area burned for the period 2010 to 2039, with red colors indicating areas with the greatest increase in area burned annually in wildfires, and dark blue the least. Image via University of Arizona.

Environmental scientist Don Falk of the University of Arizona led this study. Falk said in a statement:

We used 34 years of climate data to calibrate area burned in 1,500 grid cells across western North America, so we could capture the different ways that seasonal climate regulates fire in different regions.

Read more about what was measured for the study here.

The study’s findings for western and northern North America show that about half the states and provinces are projected to have a large increase — five or more times the current levels — in total wildfire area burned.

On August 2, 2017, the Suomi NPP satellite captured this image of smoke from wildfires in the western United States and Canada. Actively burning areas are outlined in red. Image via NASA Earth Observatory.

Other states and provinces may see smaller increases, say the researchers, indicating there is no “one-size-fits-all” model. Falk said:

Ultimately, this means that the large fire seasons of recent years, such as the one just ending, are likely to occur more frequently, affecting ecosystems, communities and public safety. These will be billion-dollar fire years. We’re just not ready for fire impacts of this kind, including post-fire effects from flooding after fire.

The total cost of the 2017 fires in California alone is projected to exceed $180 billion. This includes not only the immediate costs of firefighting, but also the much larger costs of landscape rehabilitation; medical and hospital costs; insurance losses and the costs of replacing thousands of homes and other buildings; lost economic productivity from the destruction of businesses; repair and replacement of key infrastructure such as roads, power lines and dams; and weeks of lost income by employees.

2017’s Thomas Fire in California destroyed 1,063 structures and damaged 280 more. Image via U.S. Forest Service.
The Thomas Fire is estimated to have a total cost of more than $180 billion. Replacing destroyed homes and other buildings is part of the cost. Image via U.S. Forest Service.

Falk said that seasonal climate changes are having the effect of making the fire season longer, so there is additional time for more acreage to burn. In years when seasonal climate drives lengthy fire seasons, fire management resources may be stretched to the limit. He said:

Wildfires act as a multiplier of other forces such as climate change, exposing more and more areas not only to the immediate effects of fire, but also to the resulting cascade of ecological, hydrological, economic and social consequences.

Seasonal climate variables in the winter and spring regulate snowpack, which forms from layers of snow that accumulate in geographic regions and high altitudes where the climate includes cold weather for extended periods during the year. Snowpacks can delay the onset of the fire season and are an important water resource that feed streams and rivers as they melt. Image via U.S. Geological Survey.
Environmental scientist Don Falk – who led this study – is chair of Global Ecology & Management in the University of Arizona School of Natural Resources and the Environment. His research areas include fire history, fire ecology, restoration ecology, landscape ecology, and impacts of land management and global change on ecosystems, including dynamics of abrupt change.

Bottom line: A recent study projects that wildfires in the western U.S. will likely get worse.

Source: Direct and indirect climate controls predict heterogeneous early-mid 21st century wildfire burned area across western and boreal North America

Read more from University of Arizona

March 5, 2018

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