Résumé
This paper analyzes the current and future status of forests in Ukraine
and Belarus that were contaminated after the nuclear disaster in 1986.
Using several models, together with remote sensing data and observations,
we studied how climate change in these forests may affect fire regimes. We
investigated the possibility of 137Cs displacement over Europe by studying
previous fire events, and examined three fire scenarios that depended on
different emission altitudes of 137Cs, assuming that 10% of the forests
were affected by fires. Field measurements and modeling simulations
confirmed that numerous radioactive contaminants are still present at
these sites in extremely large quantities. Forests in Eastern Europe are
characterized by large, highly fire-prone patches that are conducive to
the development of extreme crown fires. Since 1986, there has been a
positive correlation between extreme fire events and drought in the two
contaminated regions. Litter carbon storage in the area has doubled since
1986 due to increased tree mortality and decreased decomposition rates;
dead trees and accumulating litter in turn can provide fuel for wildfires
that pose a high risk of redistributing radioactivity in future years.
Intense fires in 2002, 2008 and 2010 resulted in the displacement of 137Cs
to the south; the cumulative amount of 137Cs re-deposited over Europe was
equivalent to 8% of that deposited following the initial Chernobyl
disaster. However, a large amount of 137Cs still remains in these forests,
which could be remobilized along with a large number of other dangerous,
long-lived, refractory radionuclides. We predict that an expanding
flammable area associated with climate change will lead to a high risk of
radioactive contamination with characteristic fire peaks in the future.
Current fire-fighting infrastructure in the region is inadequate due to
understaffing and lack of funding. Our data yield the first cogent
predictions for future fire incidents and provide scientific insights that
could inform and spur evidence-based policy decisions concerning highly
contaminated regions around the world, such as those of Chernobyl.