On April 26, 1986, the Chernobyl nuclear plant in Ukraine released a plume of radiation that eventually blanketed an estimated 77,000 square miles of Europe and Eurasia. While the worst of the contamination occurred near the plant — an area still closed to human habitation, now referred to as the exclusion zone — the effects are still seen further afield as well. Radioactive wild boars roam German forests, and radioactive mushrooms grow in Bulgaria.

Now, an international team of experts warns that Europe could receive fresh doses of Chernobyl radiation from forest fires.

Radioactive isotopes of cesium, strontium and plutonium take decades to millenniums to decay. The contaminants remain in soil and in plants that, once on fire, can release them into the air.

Climate models predict that rising temperatures combined with stable or declining precipitation will increase the risk of wildfires in the already fire-prone Chernobyl landscape.

Forest covered just 50 percent of the area before the disaster, but trees and brush now cover 70 percent of the exclusion zone — an area about four times the size of New York City. Fire prevention and fighting capabilities there are minimal.

Timothy Mousseau, a biologist at the University of South Carolina, and his colleagues created a computer model that incorporates fire patterns, climate predictions and field data collected in contaminated areas in Ukraine and Belarus.

According to their analysis, published in Ecological Monographs, wildfires that broke out in the exclusion zone in 2002, 2008 and 2010 have cumulatively redistributed an estimated 8 percent of the original amount of cesium-137 released in the 1986 disaster.

“We’ve invested billions to put a new cover over the old reactor building,” Dr. Mousseau said. “But forest fires have the ability to remobilize radioactive material from the original event.”

While the researchers did not predict how much radioactive material might be redistributed in the future, they warn that large blazes could leave significant amounts of radioactive soot around Chernobyl and across Europe, possibly leading to crop contamination.

How much of a health threat this would pose is unknown. But, Dr. Mousseau pointed out, “There is never a positive consequence of having increased amounts of mutagenic materials in our environment. It’s always negative.”