A new analysis of projected fire scenarios shows that the number and extent of wildfires will decrease worldwide later this century amid rising precipitation, population density and gross domestic products — but with a few concerning catches, as deforestation fires are still set to increase in some areas.

While wildfires should decrease worldwide by the 2050s and into the 2090s, harmful fires as a result of deforestation and degradation, the sudden or gradual drop in a forest's ecological function, may become more common in Australia, South America and Indonesia as forests continue to be burned down for pasture, according to a study published April 9 in Earth's Future.

Recent fires that devastated California and Australia, turning San Francisco's skies a hazy orange and denting koala bear populations, showed Park that these blazes were an important issue, and helped inspire her research, she said.

"Usually fire is not a bad thing for a terrestrial ecosystem, but deforestation fires can be a big problem," said lead author Chaeyeon Park, an associate postdoctoral researcher of landscape architecture at the National Institute for Environmental Studies in Japan. "Compared to natural wildfires, those fires can cause many negative impacts on ecosystems and human health."

Park and her colleagues used the Community Land Model 5, a type of land surface model that scientists use to quantify how ecosystems affect various ecological processes, including fires. According to Park, the Community Land Model is an effective prediction tool because it accounts for human activity and land use, as well as changes in GDP. 

Her team showed that by the 2090s, the area burned by deforestation and degradation fires could shrink from the current 73 million hectares per year to between 46 million and 66 million hectares per year, while total fire area will decrease from over 452 million hectares to between 184 million and 378 million hectares, depending on climate forecasts. One hectare is equal to 10,000 square meters, or about 2.5 acres. 

Climate change was a significant force in reducing fires globally, because it generated higher precipitation in many parts of the world. But it may not have been the greatest driving factor behind this overall reduction. For Park, the solution is more economic. 

In a prior study, for example, Park found that increases in GDP per capita reduce fires more than any other variable. According to her, countries with a higher GDP per capita tend to have different land management skills and technologies that are better-suited to avoiding fires. 

These countries may succeed at preventing fires within their borders, but they export deforestation to poorer countries, according to a recent analysis of consumption patterns across Europe and the U.S.

Despite formulating an overall positive prediction for the future of wildfires, the combination of climate change and human activity may still foster greater fires in crucial areas, including the Amazon rainforest, which was the only area Park found where climate change would reduce precipitation, rather than increase it. 

In the Amazon, slash-and-burn agriculture, where farmers burn sections of forest to create more land or rejuvenate soil, will continue to spark deforestation fires, as climate change reduces precipitation. These trends work together to promote deforestation and degradation fires in the Amazon, while they decrease elsewhere.

According to Park, world governments should aim to bolster fire-monitoring policy and fire education within their countries to help lessen the threat of degradation fires. Predicting the amount of carbon emitted by these fires can also help governments reach net-zero carbon emissions goals through increased awareness of these vulnerable areas.

This study represents the first step in Park's fire research. For future studies, she aims to examine the human-health connection between future-fire models and exposure to PM 2.5, fine particulate matter from a variety of sources, including fires, that can settle in the lungs and trigger serious health problems, according to the U.S. Environmental Protection Agency.  

The study, "How will deforestation and vegetation degradation affect global fire activity?" published April 9 in Earth's Future, was authored by C.Y. Park, K. Takahashi, J. Takakura and A. Ito, National Institute for Environmental Studies; F. Li, Chinese Academy of Sciences; S. Fujimori, Kyoto University; T. Hasegawa, Ritsumeikan University; and D.K. Lee, Seoul National University.