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Researchers at the University of California, Irvine and other institutions have spotted a contradiction in worldwide wildfire trends: Despite a 26% decline in total burned area from 2002 to 2021, the number of people exposed to wildfires has surged by nearly 40%.

The study, in Science, revealed another statistic that may come as a surprise to people who rely primarily on Western news sources: While high-profile wildfire disasters in the United States, Canada and Australia often dominate headlines, the researchers found that 85% of all human exposures to wildfires during that period occurred in Africa.

Just five central African countries—Congo, South Sudan, Mozambique, Zambia and Angola—accounted for half of all global human exposure. In contrast, the United States, Europe and Australia collectively constituted less than 2.5% of the total.

"Nevertheless, the western U.S. and particularly California are hot spots of intense fires globally," said senior author Mojtaba Sadegh, an associate professor of civil engineering at Idaho's Boise State University who earned a Ph.D. in civil and environmental engineering at UC Irvine in 2015.

"Our previously published study shows that California experiences a disproportionately large share of U.S. fire impacts, accounting for 72% of human exposures despite comprising 15% of the nation's burned area."

The researchers analyzed population data and more than 18.6 million fire records from 2002 to 2021 to find that an estimated 440 million people worldwide were exposed to a wildfire encroaching on their home during this period—a number roughly equivalent to the entire population of the European Union.

They discovered that human exposure to wildland fire increased by 7.7 million people, an average of 382,700 persons per year during the study period. This surge in human exposure was prompted not by a global jump in fire activity but primarily by population growth and migration into fire-prone landscapes.

Another factor illuminated by the research is a significant rise in the intensity of wildfires in North and South America. This is linked to the climate change-driven amplification of "fire weather," which includes conditions like increased heat, lower humidity and strong winds.

Extreme fire weather has grown by more than 50% over the past four decades globally.

When combined with such human activities as land development and historical fire suppression practices, this trend has led to an escalating risk of destructive fires in regions like California. across the state.

In Europe and Oceania, the study noted a decline in wildfire exposures, mainly because of population shifts from rural to urban areas. This highlights how both social and environmental factors play critical roles in shaping wildfire risk.

"The global paradox of decreased burn area and increased human impacts we uncovered … is due largely to an increasing overlap between human settlements and fire-prone landscapes," said co-author Amir AghaKouchak, UC Irvine Chancellor's Professor of civil and environmental engineering.

Underscoring a growing human vulnerability to wildfires—particularly in regions that receive little international attention—the research emphasizes the urgent need for proactive mitigation strategies to protect communities from the burgeoning threat of wildfires. These include vegetation management techniques like prescribed fires, public education and engineering solutions to reduce human-caused ignitions.

"As climate change intensifies fire weather and global populations continue to expand into fire-prone zones, proactive mitigation will be increasingly critical to reduce the risk of future wildfire disasters," AghaKouchak said.