You Asked: When Will Polar Bears Go Extinct?
by
Robert Newton|November 30, 2021
Whether that happens depends on what happens to the sea ice in the Arctic, which serves as an important habitat for the polar bears primary food source: seals. If the ice melts every summer season and comes new every winter season, then the winter season ice will be reasonably thin– only about 1 to 1.5 meters thick– and flat. Its possible that polar bears will develop away by offering up on the ice, moving back into the forest, and mating with brown bears. Polar bears as polar bears will definitely stop to exist once the ice stops to exist. That was one of our studys findings– that if individuals are able to support the worldwide mean temperature at about two degrees centigrade, then a fair amount of summer ice will persist going forward for the foreseeable future, and the winter ice will continue and there may be sufficient multi-year ice for polar bears to endure.
A polar bear with its cub. Picture: AWeith/Wikimedia Commons
“You Asked” is a series where Columbia Climate School professionals take on reader concerns on science and sustainability. The following concern was submitted by among our Instagram fans, and the response originates from Robert Newton, a senior research scientist at the Lamont-Doherty Earth Observatory.
Q: How fast will polar bears go extinct at the rate that worldwide warming is occurring?
Robert Newton research studies Arctic environment change at Columbia Universitys Lamont-Doherty Earth Observatory.
Whether that happens depends on what happens to the sea ice in the Arctic, which serves as an essential habitat for the polar bears primary food source: seals. And the sea ice depends very securely on what occurs to carbon dioxide emissions, and we do not know whats going to occur there.
What our group found in a recent study, using model runs and standard physics, is that if we continue to produce CO2 into the atmosphere at the historical rates, then at some point in this century, summertime sea ice will disappear nearly totally in the Arctic– millions of square kilometers of sea-ice loss. That is an issue for polar bears due to the fact that their food source, seals, rely on sea ice. If the ice melts every summer season and comes brand-new every winter season, then the winter season ice will be relatively thin– only about 1 to 1.5 meters thick– and flat.
Some polar bear populations actually can den and birth on land. But even those populations need a thick, corrugated platform of sea ice to hunt for seals. If the seals are not denning and you dont have puppies in the spring, then the polar bears lose a major food source.
At some time later in the century, if things continue as they have actually been, then the winter ice will also disappear. At that point, its difficult to picture substantial populations of polar bears enduring.
There is evidence from DNA that some polar bears may be mating with brown bears. Its possible that polar bears will evolve away by offering up on the ice, moving back into the forest, and mating with brown bears. But polar bears as polar bears will definitely disappear when the ice ceases to exist. Theyre not well adjusted to hunt on land. They mix in magnificently on the sea ice; they stand out like crazy in the forest. Theyre fantastic swimmers, adapted to hunting marine mammals. Theres no reason to think that they would make it through if they need to forage and hunt on the tundra or in wooded locations on land.
To address your question, my finest guess is that polar bears could go extinct someplace in between 2050 and 2100.
That said, all of the designs weve run and our understanding of the physics of ice growth and ice melt indicate that the sea ice will follow the temperature of the environment very closely. The sea ice is disappearing extremely rapidly as the northern latitudes warm, however it ought to likewise return really quickly if we manage to get greenhouse gas emissions under control and to minimize co2 in the atmosphere.
That was among our research studys findings– that if people are able to support the international mean temperature level at about 2 degrees centigrade, then a reasonable amount of summer ice will continue moving forward for the foreseeable future, and the winter ice will continue and there might suffice multi-year ice for polar bears to survive. And if, at some future date, humans have the ability to catch co2 from the atmosphere and sequester it underground to bring international temperatures back down, then theres every reason to think that the ice will return within a couple of years as the international mean air temperature level boils down. In that sense, the future of the species is really in our hands.
