A hotter world is also a drier world. Less precipitation in the form of rain and snow. Warmer temperatures also contribute to earlier snowmelt and more evaporation. Climate change also augurs infect infestations that kill trees and provide more fuel for wildfires. Increasingly severe storms also contribute to more lightening and this is yet another wildfire risk factor associated with climate change. Here is a brief primer reviewing some of the evidence linking wildfires to climate change.
Wildfires have always occurred in nature but human activities have caused the Earth to warm and this is increasing the number and intensity of fires. The world has warmed by an average of one degree Celsius since pre-industrial times, however, in some forests the temperature has increased by 1.5 degrees Celsius.
As reported by Yale Climate Connection, Hotter drier conditions have almost doubled the number of wildfires in the West and big wildfires are 5 times more common in the West now than in the '70s. Forty years ago there was an average of 20 large fires each year in the West, now we are averaging well over 100 large fires each year. The fire season has expanded by almost 50 percent and is now two-and-a-half months longer than it was 40 years ago.
In 2014 the National Climate Assessment study contributed to the growing body of research that corroborated the view that climate change is increasing wildfire risk. Average annual temperatures worldwide have increased by 1.9 degrees Fahrenheit in the last decade. Winter snow packs melt up to 4 weeks earlier than in previous decades, leaving landscapes drier and making it easier for wildfires to spread when they start.
The most conclusive evidence yet comes from a study titled, "Impact of anthropogenic climate change on wildfire across western US forests". While preceeding studies have said that there is a clear hypothesized link between wildfires and climate changes this study observes and quantifies the evidence for attribution. According to this research human-caused, climate change has doubled the amount of wildfires. This translates to the burning of an additional 10.4 million acres of wildfires between 1984 and 2015.
This study by John T. Abatzogloua and A. Park Williams explicitly makes the connection. Abatzoglou claimed that his research found that anthropogenic climate change played a prominent role in forest fire activity in the western United States. "We’re no longer waiting for human-caused climate change to leave its fingerprint on wildfire across the western U.S. It’s already here," Abatzoglou said in his report.
In the "Years of Living Dangerously", Randy Anderson, a longtime firefighter, and superintendent of the Snake River Hotshots said, "You can’t deny the fact that it’s getting warmer and drier. And we’re seeing it in the effects of the wildland fires." Big fires are getting bigger. Anderson explained that when he first started fighting forest fires in 1987 he was battling fires in excess of 20,000 acres. Now we are seeing fires as big as 400,000-acres fires.” He cautions that Western wildfires continue to worsen as the Earth keeps warming.
"No matter how hard we try, the fires are going to keep getting bigger, and the reason is really clear. Climate is really running the show in terms of what burns. We should be getting ready for bigger fire years than those familiar to previous generations," Professor Williams said. "I'd expect increases to proceed exponentially for at least the next few decades."
Climate Central reports:
"Climate change is making wildfire seasons longer and more intense. The trend bends toward bigger, more destructive and drought-driven blazes in the West. On average, wildfires burn six times the acreage they did 45 years ago, Since the 1970s, the frequency of wildfire has increased 1,000 percent in the Pacific Northwest, 889 percent in the Northern Rockies, 462 percent in the Southwest and 256 percent in California’s Sierra Nevada as the mountain snowpack melts earlier and the fire season lengthens, according to Schoennagel’s team’s research. In the northern latitudes, the boreal forest is burning at a rate unprecedented rate. Wildfire season arrives a month earlier than it did in 1970. In Alaska, the number of big wildfires has doubled in the last 65 years".
The lead author of another wildfire study said, "wildfires are increasing beyond our capacity to control, especially with more people in fire’s way." Tania Schoennagel, a research scientist at the University of Colorado-Boulder’s Institute of Arctic and Alpine Research. "As wildfires continue to increase, more and more communities are threatened, and suppression simply will not be able to keep up," Schoennagel said. "Through suppression, we’ve tried to make fire adapt to us, but going forward, we will have to adapt to it...The first step is to expect that wildfire will come to your door rather than assume it will not."
"The public needs to become aware that fire is a natural process and that increases in the frequency and size of large fires are inevitable," Williams said.
To make matters worse there is a dangerous feedback loop between wildfires and climate change. Not only are wildfires exacerbated by climate change they are also a contributing factor. Wildfires release large amounts of carbon dioxide and decrease the number of trees available to absorb it,
Prescribed burns and thinning can help but the real solution is to slow temperature rises and this means weaning ourselves off of fossil fuels. Will Ashley-Cantello, chief adviser on forests at WWF-UK, said the research underlined the need to stop using fossil fuels and cutting down forests. "We must reduce our climate warming emissions worldwide and mimic natural processes in the way we manage forests. The age of fossil fuels and deforestation has to end now."
California Fires are Part of a Global Phenomenon
Climate Change Fueling Wildfires in North America and Russia
Climate Impacts in California
Video - The Relationship Between Climate Change & Wildfires
Climate Change Fueling Forest Fires in the North American West (July 2015)
Wildfires Peat and Carbon
Video - How Climate Change Fuels Wildfires