Japan has a bear problem, at least in the north.
In 2025, bears killed more than a dozen people in the country and injured more than 200 others. That’s way up from the previous record, set in 2023, of six fatalities. The threat grew so severe last fall — when bears are out looking for more food in preparation for hibernation — that the government called in the military, deploying troops to help trap bears in the northern prefecture of Akita, the epicenter of the attacks.
In November, meanwhile, the US embassy in Tokyo issued a rare “wildlife alert” warning US citizens to watch out for bears.
Most of the recent incidents involved Asiatic black bears, which are not normally aggressive, according to Hengjun Xiao, an environmental researcher at Japan’s Keio University. That makes what he describes as the recent “bear crisis” all the more extraordinary.
So what’s going on? It comes down to a strange connection between bears and clouds.
By analyzing climate and satellite data, Xiao found that a weather anomaly tied to climate change may explain the deadly surge.
The details are complex, but the new paper — as well as a much lengthier, unpublished study that’s currently under peer review — suggests that climate change is weakening winds, known as the westerlies, that bring dry air into Japan and prevent moist air from the Pacific from flooding in. That’s making northern Japan cloudier.
With more clouds, less light reaches the forest. And this is key: Without light, forests fail to produce young shoots, nuts, and other foods that bears rely on, the study argues. That leaves bears hungry and likely to venture into human settlements in search of sustenance.
by vox