This article originally appeared on VICE IN.
Climate change is starving polar bears into extinction, according to a study published on June 21. The research, published in the science journal Nature Climate Change, predicts that one of the two largest land carnivores can be extinct by the end of this century.
Polar bears require sea ice for capturing seals, their primary food. As global warming and sea ice loss continue, their population is expected to fall heavily.
This new study is the first to put a timeline on their likely demise: it concludes that polar bears in 12 subpopulations of the Arctic, almost 80 percent of the total population, will be decimated in less than 80 years.
Enough data for the other subpopulations isn’t available yet to determine their fate. Scientists estimate that there are fewer than 26,000 polar bears left, spread out across 19 subpopulations from the icescapes of Svalbard, Norway, to Hudson Bay in Canada to the Chukchi Sea between Alaska and Siberia.
The study considered a scenario where the Earth's average surface temperature will rose 3.3 degrees Celsius above the preindustrial benchmark. One degree of warming so far has triggered heatwaves, cyclones, and a host of disasters in the past five years itself.
The Arctic is already warming twice as fast as the planet as a whole. Even if humanity were able to cap global warming—a hugely ambitious venture—most of the subgroups would still be lost.
Scientists also add that the polar bears' ‘vulnerable’ status on the International Union for the Conservation of Nature (IUCN) Red List of endangered species does not accurately reflect their plight. Categories established by the IUCN are based mainly on threats such as poaching and habitat encroachment that can be addressed with local action on the ground.
"Think of it this way: If I were to push you off of the roof of a 100-story building, would your risk level be 'vulnerable' until you pass by the 10th floor?" the chief scientist of Polar Bears International Dr Steven Amstrup, who was involved in the study, told news agency AFP. "Or would you be 'endangered' all the way down? The only way to save them is to protect their habitat by halting global warming."
The threat to the bears’ survival is not rising temperatures per se, but the predators' inability to adapt to a rapidly shifting environment that is the consequence of rising temperatures. Shrinking sea ice has cut short the time bears have for hunting food. This has forced the animals onto land—further away from their food supplies—for longer periods.
Prolonged fasting and reduced nursing of cubs due to insufficient nutrients and energy available will lead to rapid declines in reproduction and survival. "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,” Amstrup told BBC News.
The new approach overlays two sets of data: one is the expanding fasting period of polar bears — the period between two hunts — and the second is Climate Change projections tracking the decline of sea ice until the end of the century. By estimating how thin and fat polar bears can be, as well as their energy use, they calculated the number of days polar bears can fast before survival rates begin to decline.
Scientists say that their dwindling bodyweight undermines the bears’ chances of surviving Arctic winters without food. "The bears face an ever longer fasting period before the ice refreezes and they can head back out to feed," Amstrup told AFP. While fasting, bears move as little as possible to conserve energy. Sea-ice loss and population declines create more problems, however: bears are having to expend more energy searching for a mate. This, in turn, affects survival.
Follow Satviki on Instagram.