Polar bears will be disappeared by the end of the century unless more is done to stop climate change, a study forecast.
Scientists say some inhabitants have already reached their survival boundaries as the Arctic sea ice shrinks.
The carnivores depend on the sea ice of the Arctic Ocean to a quest for seals.
As the ice breakdowns, the animals are required to travel for long distances or on to shore, where they scuffle 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.
“Polar bears are already sitting at the top of the world; if the ice goes, they have no place to go,” he said.
Polar bears are considered as vulnerable to extinction by the International Union for Conservation of Nature (IUCN), with climate change a vital reason in their decline.
Studies show that deteriorating sea ice is likely to decrease the number of polar bears, perhaps significantly.
The new study, published in Nature Climate Change, puts a timeline on when that might happen.
By demonstrating the energy use of polar bears, the researchers were able to analyse their endurance limits.
Dr Steven Amstrup, a chief scientist of Polar Bears International, who was also involved in the study, told: “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”.
The scientists also think when these thresholds will be strained in different parts of the Arctic. This may have already occurred in some areas where polar bears live, they said.
“Showing how imminent the threat is for different polar bear populations is another reminder. We must act now to head off the worst of future problems faced by us all,” said Dr Amstrup.
“The way we’re on now is not a decent one, but if humanity gets its turn together, we have time to save polar bears. And if we do, we will help the rest of life on Earth, including ourselves”.
Under the status of high carbon emissions, it’s likely that all but a few polar bear populations will downfall by 2100, the study found. And even if reasonable emissions reduction targets are reached, several populations will disappear.
The findings match earlier forecasts that polar bears are likely to persist to 2100 only in a few populations very far north if climate change continues unabated.
Sea ice is freezing seawater that floats on the ocean surface, forming and melting with the polar seasons.
Some persevere year after year in the Arctic, providing a key environment for wildlife such as polar bears, seals, and walruses.
Sea ice that stays in the Arctic for longer than a year has been deteriorating at a rate of about 13% per decade since satellite records began in the late 1970s.
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Zulker Naeen is a South Asia Fellow at Climate Tracker and freelance climate journalist from Bangladesh. He has three years of experience in the field. Zulker developed all his courses with the support of other experienced Climate Tracker staff credited on the course landing page.
As a young climate advocate, his fellowship aims to share knowledge of climate change. Climate Tracker is a global media network closely works on Climate Change.