Polar bears will be wiped out by the end of the century unless more is done to tackle climate change, a study predicts. Scientists say some populations have already reached their survival limits as the Arctic sea ice shrinks. The carnivores rely on the sea ice of the Arctic Ocean to hunt for seals. As the ice breaks up, the animals are forced to roam for long distances or on to shore, where they struggle to find food and feed their cubs. The bear has become the “poster child of climate change”, said Dr Peter Molnar of the University of Toronto in Ontario, Canada.
Studies show that declining sea ice is likely to decrease polar bear numbers, perhaps substantially. The new study, published in Nature Climate Change, puts a timeline on when that might happen. By modelling the energy use of polar bears, the researchers were able to calculate their endurance limits. Dr Steven Amstrup, chief scientist of Polar Bears International, who was also involved in the study, told BBC News: “What we’ve shown is that, first, we’ll lose the survival of cubs, so cubs will be born but the females won’t have enough body fat to produce milk to bring them along through the ice-free season. “Any of us know that we can only go without food for so long,” he added, “that’s a biological reality for all species”.
Under a high greenhouse gas emissions scenario, it’s likely that all but a few polar bear populations will collapse by 2100, the study found. And even if moderate emissions reduction targets are achieved, several populations will disappear. The findings match previous projections that polar bears are likely to persist to 2100 only in a few populations very far north if climate change continues unabated.
Source: BBC
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