According to a new study, humans are the first responsible for making the wildfire seasons last longer and affect even more areas of the United States in the past years. The investigation showed how over the past 21 years, there had been over 840,000 blazes in wood areas in the country, which represents a significant increase in comparison with other years.

A team of researchers from the University of Massachusetts analyzed over 20 years of U.S. federal records regarding wildfires during the fall, spring and winter seasons of the period between 1992 and 2012. The study found that in 84 percent of wildfire cases, humans were responsible, as that produced that the length of the regular wildfire season tripled in duration and increased the amount of damaged acreage in 50 percent. All the findings done by the investigation team co-led by Bethany Bradley from the University of Massachusetts were published in the journal Proceedings of the National Academy of Sciences.

Humans are responsible for 84 percent of wildfire cases. Image credit: Ted S. Warren / AP / Business Insider

“There cannot be a fire without a spark,” said Jennifer Balch, Director of CU Boulder’s Earth Lab and an assistant professor in the Department of Geography and lead author of the new study. “Our results highlight the importance of considering where the ignitions that start wildfires come from, instead of focusing only on the fuel that carries fire or the weather that helps it spread. Thanks to people, the wildfire season is almost year-round.”

The researchers involved in the study used the U.S. Forest Service Fire Program Analysis-Fire Occurrence Database to analyze all the registers concerning wildfires that required the assistance of local or federal agencies between the 1992-2012 period. The team omitted all the intentionally set burns and managed agricultural fires to obtain an objective result. Of all the 1.5 million wildfires registered in those 21 years, humans were the responsible of the ignition in 84 percent of the cases (1.26 million), while the other 16 percent were lighting-ignited wildfires.

The United States vs. Wildfires

Over the last ten years, the United States has faced some of the worst fires ever registered in modern history, especially in the west zone of the country. Currently, the amount of money spent by the federal government in the fight against wildfires is $2 billion, as many political figures have expressed their concerns about this national problem.

Both the intensity and duration of any wildfire are a matter of general concern since it could affect a whole community significantly. A considerable wildfire in a rural area could reverberate severely in a zone’s agricultural areas, ecosystem, and other sectors, without adding the potential cost of extinguishing a fire for the government, which is very high.

For example, in Colorado, during the studied period between 1992 and 2012, 30 percent of the wildfires registered were produced by humans, as those particular fires were responsible for the burning of over 1.2 million acres. When comparing the human-wildfire season with the lightning-wildfire season, there is a considerable difference, as the one caused by humans lasts 93 days and the other one just 43. This increase during the wildfire season duration is creating concern among public authorities as they recognize the seriousness of the issue.

Over the last ten years, the United States has faced some of the worst fires ever registered in modern history. Image credit: Max Whittaker / AP / Business Insider

According to Dr. Balch, author of the study, these findings do not show that climate change is not having a significant role when it comes to producing negative consequences to the ecosystem, but it must raise awareness regarding the human action overlapping with climate change and the repercussions this it is generating. She explained how our fields and grasslands are getting drier, which makes more probable the ignition of a particular area due to human influence.

The study showed how the lighting-wildfire season is often concentrated in the summer months of the year, while the human-related wildfires are spread among several seasons through the year. In general, humans added up to 40,000 fires in average during the spring, winter and fall seasons annually, which is about 35 times more than the number of wildfires produced by lightning.

“We saw significant increases in the numbers of large, human-started fires over time, especially in the spring,” said Bethany Bradley, an associate professor at University of Massachusetts Amherst and co-lead author of the research. “I think that’s interesting, and scary, because it suggests that as spring seasons get warmer and earlier due to climate change, human ignitions are putting us at increasing risk of some of the largest, most damaging wildfires.”

The new findings presented this Saturday have direct implications regarding how federal agencies are managing wildfire situations in several states. In the same issue, it shows how human action can have such a dramatic repercussion regarding wildfire situations countrywide. Dr. Balch recommends that people should try to make controlled and small fires in order to reduce the number of ignitions as soon as possible. The good news is that according to the investigation team, it is possible to get great results in the mid-term, in theory, if people start collaborating with the authorities by following safety procedures they recommend.