Can polar bears and people coexist?
We have an odd relationship with polar bears.
As we watch them pace inside their zoo enclosures, or marvel at their portrayal within natural history documentaries, we are drawn to their big paws, fluffy white fur and button-like black noses. We find polar bear cubs adorable.
We grant them special status, elevating polar bears to represent all that is most majestic about the frozen parts of our planet.
Yet we often forget that polar bears are killers.
It is in their nature. As the top carnivore in their icy world, and the largest land predator alive, polar bears hunt to survive, mainly stalking other large mammals such as seals, walruses and whales.
End Quote Polar bear expert Jon Aars of the Norwegian Polar Institute in Tromsø
When they attack humans it will usually be because they are very hungry”
Occasionally, and tragically, we now know, they will also kill people, as evidenced by the death of a young British tourist in Norway and the mauling of four others.
Incidents like this, however, could become more common.
The reason is climate change. As rising temperatures melt the sea ice, the number of polar bears may rapidly dwindle. That could mean that there are far fewer bears surviving for people to come into conflict with. But if polar bear numbers fall, we may revere them even more, with more tourists and adventurers flocking to catch a final glimpse of these animals.
If the sea ice retreats, it will also mean that more polar bears will be forced to hunt further inland. And that means more polar bears roaming around parts of the Arctic and sub-Arctic that people call home.
"I can't comment on the particular details of the bear attack in Svalbard but, unfortunately, polar bear-human conflicts are very likely going to increase in many parts of the circumpolar Arctic as climate warming progresses," Gregory Thiemann, professor of environmental science from York University, Ontario, Canada, told BBC Nature.Attacks rare
Polar bears roam the frozen seas of all the Arctic nations: Russia, Alaska in the US, Canada, Greenland and Norway, where the recent fatal attack occurred near the remote Von Postbreen glacier in Svalbard.
Generally, attacks on humans are extremely rare.
One study, a review of bear-inflicted injuries and fatalities published in 1999 in the journal Wilderness and Environmental Medicine, documents the number of incidents involving polar bears up until that time
- Between 1980 and 1985 in Alaska, there was only one recorded injury caused by a polar bear, and no deaths
- Over a 15-year period in Svalbard, Norway, other researchers documented polar bears killing one person and injuring three others. At least 46 polar bears were killed by people in the same time frame
- In a 20-year period in Canada, six human deaths and 14 injuries were attributed to polar bears. During the same period, 251 bears were killed by people "in defence of life and property"
- Polar bears are massive, with males standing up to 2m tall at the shoulder and weighing half a tonne
- Along with the grizzly bears of Kodiak Island, Alaska, they are the largest living land predator
- A single swipe of a large male polar bear's paw could be enough to kill a person
- Though polar bears have been known to track and hunt people, attacks are rare.
- Other bear species, such as brown bears, kill and injure more people each year, in part because they come into contact with people more frequently
Of the six deaths and 14 injuries in Canada, 15 were considered to be acts of predation by the bear, and one by a polar bear defending her cubs. One was attributed to both, while the other was unresolved
Until 1999, two deaths and two injuries had occurred in the town of Churchill in Manitoba, Canada, an inland seaport inhabited by around 1,000 people and a similar number of bears.
One death was a sudden encounter between a bird hunter and the bear. The hunter approached the bear, was killed and eaten.
The other involved a man who walked down the high street in the middle of the night carrying cooked meat. He too was killed and partially consumed by the bear.
Today the inhabitants of Churchill meet polar bears frequently.
Hungry bears often wander into town on their way back to hunt on the sea ice of Hudson Bay.
These bears are tolerated but are quickly removed, a procedure filmed by the BBC documentary series Human Planet.
If possible, they are trapped using seal meat as bait before being anaesthetised and transported by helicopter some 60km (37 miles) away from the town.
In the past, as many as 75 bears a years were removed this way. But in recent years, this number has halved as the population of polar bears in the area is in decline.Coming ashore
Recent studies have suggested that climate change will trigger a dramatic and sudden fall in the number of polar bears.
Last year, Dr Peter Molnar of the University of Alberta, Edmonton, Canada, published the first research to directly model how changing climate will affect polar bear reproduction and survival.
Based on what is known of polar bear physiology, behaviour and ecology, it predicted that pregnancy rates would fall and fewer bears would survive fasting during longer ice-free seasons.
These changes would happen suddenly as bears pass a "tipping point".
Other recent studies suggest that the long-term survival of polar bears is being threatened by man-made pollution that is reaching the Arctic.
Industrial chemicals such as mercury and organochlorines may have a cumulative and potentially fatal impact on the bears' bones, organs and reproductive and immune systems.
The stress caused by the combined impact of pollution and dwindling sea ice is even causing polar bears to shrink in size over the past century, according to research which compared bear skulls from the early 20th Century with those from the latter half of the century.
But as bears starve, they may also begin to spend more time ashore - seeking food - than out on the dwindling sea ice.
"As climate warming progresses, polar bears are going to spend more time on land and they are going to be more nutritionally stressed," said Dr Thiemann.
"These two factors are going to increase the risk of bears coming into conflict with people."
"Climate change is a problem for the bears," agreed Jon Aars of the Norwegian Polar Institute in Tromsoe.
"There are several places where we see more bears on land because of less sea ice, particularly in Svalbard.
"They do almost all the hunting on the sea ice," he said.
"That's where the seals are resting. So when you have shorter periods where you have no sea ice, bears have to starve for longer periods.
"They're actually very good at starving for a while - they can starve for several months. But they do get desperate for food as these starvation periods get longer."
Polar bears have already been seen seeking out alternative food sources, for example raiding geese and murre colonies in Canada for eggs and chicks.
The concern now is that polar bears and people will increasingly frequent the same stretches of icy wilderness.Humans as food
The remote Von Postbreen glacier, at the end of a large fjord in Svalbard, Norway, may have already become such a place.
- Frozen Planet, a new landmark natural history documentary series documenting the fate of the Arctic and Antarctic, will be broadcast later this year on BBC One
"There are many other places in the Arctic where the bears are still hunted. [But] from 1973, the bears have been protected in Svalbard," said Dr Aars.
"They used to be hunted, so local polar bears were shot out. Now they start coming back so we see more bears in the fjord close to where people live."
He says the place where the attack happened carries a high risk of meeting polar bears.
"If you look at the big fjord where this happened, you have a bit of sea ice at this time of year, which attracts the polar bears."
But "this time of year is particularly hard time for polar bears, because the sea ice is at its lowest".
That also means there are fewer seals, the polar bears' usual prey, resting on the sea ice.
"And the later you get in summer, the longer the bears have been without much food.
"When they attack humans it will usually be because they are very hungry."
According to Dr Thiemann, more will need to be done to avoid such tragic accidents happening with greater frequency.
"In the years ahead, it will be critical for coastal communities and governments to prepare for these increasing polar bear-human interactions and devote the time and resources necessary to develop plans aimed at minimising the risk to people and polar bears," he said.