Melting ice in the Arctic Ocean can make many polar bears disappear this century, say researchers in an international study published Monday in the journal Nature Climate Change .

It is the first time that scientists have predicted when and how the animals will disappear. "It has been clear for some time that polar bears will suffer from climate change, but it was not yet clear when we could expect a decline in their survival rates and reproduction," said University of Toronto biologist Péter Molnár.

For the study, thirteen of the nineteen polar bear subpopulations were examined. In total, this concerns about 80 percent of the global polar bear population. Among other things, the scientists conclude that polar bears should be ashore more often due to melting ice, which prevents them from hunting.

Polar bears may experience reduced reproduction from 2040, causing the animal to become extinct in a few habitats. They are likely to survive beyond 2100 only in the Queen Elizabeth Islands, north of Canada. Even if greenhouse gas emissions decrease, polar bears may not reproduce as easily from 2080. The survival rate of the animals is also decreasing due to starvation, among other things.

WWF: 'It's a bit of a swallow'

The World Wildlife Fund (WWF) is shocked by the conclusions of the study. "It takes a while, because what we feared for some time is now scientifically substantiated even more precisely."

"In the future there will be a lot less polar bears than there are now, because their habitat, the sea ice, is melting more and more and polar bears are forced to stay on land, where they have to fast longer and then starve. Polar bears have ice hard necessary to hunt prey such as seals ", says Gert Polet of WWF-NL, the Dutch division of the World Wildlife Fund.

At the moment, it is estimated that there are still about 26,000 polar bears worldwide. The animals depend on ice blocks to hunt for food.