Science & Technology

What’s behind the dramatic surge in California’s massive fires?

September 13, 2021

Climate change, centuries of fire extinguishing, and heat waves and droughts supercharged by the proliferation of populations increase the likelihood of large-scale, devastating fires.

If huge wildfires seem to be constantly rampant in California late summer, that’s because they do. According to the state, eight of the ten largest fires recorded in the state and 12 of the top 20 have occurred in the last five years. California Department of Forestry and Fire (Cal Fire).. These 12 fires destroyed about 4% of California’s total area, or Connecticut-sized land.

Two recent incidents, the Dixie Fire (2021) and the August Fire Complex (2020), stand out in scale.Each of these almost burned 1 million acresLarger than Rhode Island, it raged in the forests of Northern California for months. Several other large fires, as well as many small fires in densely populated areas, have proven to be devastating in terms of destroyed structures. Lost life.. California 13 20 most destructive wildfires It has occurred in the last 5 years. They collectively destroyed 40,000 homes, businesses, and parts of the infrastructure.

Wildfires in California are expanding

1970 – 2021

Remote Sensing Ecologist at Idaho State University Historical fire database, Project NASAEarth Science Applied Science Program. The database shows that about 3 percent of the state’s land surface burned between 1970 and 1980. From 2010 to 2020 it was 11%. The transition to large-scale fires is evident in the 10-year map of fire perimeter data from the National Inter-Ministry Fire Center (above).

John Keeley, a scientist at the US Geological Survey based in Sequoia National Park, said: He is one of several experts who say that the confluence of factors has caused a massive and devastating fire surge in California: anomalous drought and heat exacerbated by climate change, caused by decades of fire extinguishing. Overgrown forests, and rapid population growth along the edges of the forests.

The effects of all these fires are dramatic both from the ground and from space. The false-colored image at the top of the page, captured by Landsat 8’s Operational Land Imager (OLI), shows the scars left by Dixie’s fire. The flames destroyed 1,329 structures and cost hundreds of millions of dollars to fight. The photo below shows the charred forest of the Plumas National Forest after the Dixie fire.

Wildfire July 2021

July 31, 2021

“The current drought is unprecedented,” Keeley said. “Each of the last 30 years has experienced much worse drought than any other decade of the last 150 years.” In the short term, droughts exacerbate fires by absorbing moisture from trees and plants and making them more flammable. Let me do it.In the long run it will add A large amount of dead trees It will affect the landscape and increase the likelihood of a severe fire.

The drought from 2020 to 2021 was particularly extreme. John Abazoglow, a climate scientist at the University of California, Merced, said: “This keeps the soil and vegetation dry in much of California, allowing the landscape to carry fire that resists restraint.”

Data from the Western Regional Climate Center show that two-thirds of the northern part of the state has had only half of its normal rainfall in the last few years. Drought monitors in the United States have classified approximately 85-90% of California as experiencing “exceptional” or “extreme” droughts throughout the summer of 2021. According to data from the National Institute for Environmental Studies.

Drought Chart California

January 1, 2000-2020

Daniel Swain, a climatologist at the University of California, Los Angeles, added that one of the most direct ways climate change can affect California fires is to raise temperatures. “Heat essentially turns the atmosphere into a giant sponge, drawing water from the plants and allowing the fire to burn hotter and longer,” he said. According to meteorological data, the two years from September 2019 to August 2021 were the third warmest on record in California, about 2.9 ° (1.6 ° C) higher than average.Air can absorb about 7% more water to any extent Celsius It gets warm.

Abatzoglou said some of the tragic scenes across Northern California in 2020 were due to extreme and unusual. Dry thunderstorm siege In mid-August it ignited thousands of fires overnight. “But in 2021 I’m not very sure about bad luck,” he said. “Climate change is helping fuel warming and more rapid drying, which makes land more susceptible to major fires.”

Image of NASA Earth Observatory by Joshua Stevens and Lauren Dauphin. We use Landsat data from the US Geological Survey, around the fire at the National Inter-Ministry Fire Center, and the drought status at the US Drought Monitor / University of Nebraska-Lincoln. Photo courtesy of Inci Web.

What’s behind the dramatic surge in California’s massive fires? What’s behind the dramatic surge in California’s massive fires?

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