Al Gore used a cartoon of an exhausted, endlessly swimming polar bear to illustrate the impact humans were having on the sea ice where the bears once hunted.
Coca-Cola raised $2 million for arctic polar bears and decorated the website for the habitat preservation campaign with an adorable picture of a cub. And agency after agency has warned that climate change could make polar bears extinct by 2050.
But a group of scientists has posited another potential impact of global warming on polar bears, and it’s not nearly so adorable.
It involves you being lunch.
The paper, published this month, gets straight to the meat of the issue with its title: “Polar Bear Attacks on Humans: Implications of a Changing Climate.” The researchers represent government wildlife agencies and preservation organizations from the United States, Russia, Canada, Norway and other countries.
The higher global temperatures go, the researchers said, the more likely polar bears are to interact with humans — and possibly attack and eat them.
For hungry bears, ice floating on the sea is a perfect hunting ground. They stake out breaks in the ice that calorie-dense seals use as breathing holes. The bears wait for the marine mammals to surface or use the icy cover to creep up on sunning seals — then pounce.
But warmer temperatures mean less ice, which tilts the Darwinian game of hide-and-seek in the seals’ favor.
“But a bear’s still got to eat,” said Geoff York, with Polar Bears International, who is one of the study’s authors and has survived three encounters with aggressive polar bears. “They’re more likely to try new things, and sometimes, that might be us.”
The researchers analyzed decades of polar bear attacks, dating from the 1870s. They included one particularly gruesome story of a polar bear chomping on 16th-century Russian explorers, but the data gathered from media reports, law enforcement and government records became more consistent in the 1960s.
They found that “the greatest number of polar bear attacks occurred in the partial decade of 2010 — 2014, which was characterized by historically low summer sea ice extent and long ice-free periods,” according to the study. Fifteen attacks happened in that period.
Most attacks happened in field camps and with people traveling across the landscape — places where people expect to find polar bears and typically take precautions. About 27 percent happened in towns.
“That matches what residents and managers are saying,” York said. ” ‘We’re encountering more bears. We’re encountering them at times of the year we’re not used to. We’re encountering them more frequently. We used to go camping all summer. We don’t do that anymore.’ ”
The researchers’ findings match what others have found or theorized about how polar bears adapt to changing conditions.
The U.S. Geological Survey concluded that declining sea ice means polar bears have to walk more — and burn more calories — to stay within their preferred habitat, according to the Associated Press. Less sea ice, for polar bears, means more time on land, concluded the book “Meltdown: Terror at the Top of the World,” about a polar bear attack. Those changes have altered how the bears forage for food, a Yale study concluded, decreasing the level of mercury in their bloodstream.
The bears on land are also more likely to interact with humans, “Meltdown” says: “After all, to a starving bear, a human is just meat.”
Human activity in arctic areas has also increased as people and businesses have taken advantage of decreasing sea ice, York said. That further increases the chance of bears coming into contact with miners, fishermen and tourists.
At the same time, the researchers said, hungrier bears are taking more risks. Polar bears tend to be risk-averse, and there’s an evolutionary reason for that. A brown bear or a black bear that gets injured in a fight can still forage for nuts, berries or other forest foods to sustain it.
If a polar bear is injured and unable to hunt, that’s usually a death sentence, York said. So they hunt food not likely to fight back, like seals, and avoid humans.
Starvation changes that calculus.
“It takes it from being fat, happy bears down the street from town to skinny bears that are interested in your food, that are interested in you,” York said.
He emphasized that the study’s authors want humans to do everything they can to protect themselves from attacking bears, but human-polar bear interactions are always bad for the bear — even if it survives the initial attack.
Wary humans in communities where bears attack almost always try to find the bear and kill it, he said.
Even more damaging, they’re less likely to support polar bear conservation efforts.