Climate Change Tracker: Polar bears might disappear by 2100

In early June, this column reported that over 500 species of invertebrate animals are on the brink of extinction. Each of these species have less than 1,000 individuals left in the wild, and there’s a 94% chance that they will go extinct in 20 years. The scientists predicting this had also noted that 400 invertebrate species had already gone extinct in the past 100 years. They said this was the direct result of human intervention in the environment, in the form of degradation, pollution and climate change. Extinctions that would take about 10,000 years in normal evolutionary time frames are now occurring every century.

And now, there’s extremely bad news regarding polar bears. A new paper in Nature, titled Fasting Season Length Sets Temporal Limits For Global Polar Bear Persistence, says most polar bear sub-populations in the Arctic will be gone by 2100. The study, led by biologist Péter Molnár, says many polar bear sub-populations will face starvation and reproductive failure by as early as 2040 due to melting Arctic Sea ice. Even with moderate mitigation of greenhouse gas (GHG) emissions, most polar bear sub-populations will be similarly afflicted by 2080. According to a 2019 report, there are an estimated 26,000 polar bears in the Arctic region, divided into 19 sub-populations. The connection between GHG emissions, global heating and the loss of Arctic summer ice is the most straightforward chain of climate change impacts that we know of. What the authors of this report show is how this loss of sea ice will increase periods of summer starvation for the bears.

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As it becomes increasingly difficult for them to forage for food during the summer months due to the melting of perennial ice, polar bears are relying far longer on body energy reserves for survival. "Although polar bears can fast for months, limits are imposed by the amount of energy bears can store in body reserves before periods of food deprivation," says the study. If emissions continue at current business-as-usual rates, the scientists predict that polar bears will survive only in Canada’s northernmost Queen Elizabeth Islands archipelago. These magnificent creatures have long been portrayed as the face of the climate crisis. Soon, all we might have left are their images.

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