In a new study from CU Boulder, researchers have compared the frequency and intensity of fires in the United States, including 28,000 fires from 1984 to 2018. The intensity of the fires was gauged by using a combination of satellite photos and federal fire records.
The experts found that there were more fires in the period from 2005 to 2018 than in the twenty years before. The study revealed that fire frequency had doubled in the western and eastern part of the US, and quadrupled in the Great Plains.
The results also showed that fires in the United States grew larger and ignited more frequently in the 2000s compared to previous years.
Due to climate change, fires are expected to increase and grow in intensity into the future. Their impacts are also likely to increase.
“Projected changes in climate, fuel and ignitions suggest that we’ll see more and larger fires in the future. Our analyses show that those changes are already happening,” said study lead author Virginia Iglesias, a research scientist with CU Boulder’s Earth Lab.
“Anthropogenic effects are likely to have influenced fire patterns across the country not only indirectly through regional aridification, but also in a direct manner,” wrote the study authors. “During the last 21 years, for example, human ignitions caused 84 percent of all fires in CONUS, representing approximately 40,000 fires per year.”
“Concurrent ignition and dry fuels are prerequisites for burning. By introducing ignitions into dry landscapes, humans have tripled the length of the fire season and expanded the size of fire-prone areas. These ignitions are notoriously important in regions with sufficient dry fuel to support fires but where lightning concurrent with dry fuel is rare, such as large portions of the Great Plains and eastern United States.”
The research also shows that the ecology of fire prone areas is already changing. Forests themselves are being altered by fires as well as by changes in precipitation.
“More and larger co-occurring fires are already altering vegetation composition and structure, snowpack, and water supply to our communities,” explained Iglesias. “This trend is challenging fire-suppression efforts and threatening the lives, health, and homes of millions of Americans.”
The researchers suggest that to properly control fires, their changing nature and the resources they impact must be taken into account.
“These convergent trends, more large fires plus intensifying development, mean that the worst fire disasters are still to come,” said study co-author William Travis.
The research is published in the journal Science Advances