The polar bear regularly makes headlines as an emblem of climate change. We will remember the shocking images of a dying emaciated bear or this other on its small block of ice in the middle of the ocean. A few years ago, a study carried out using a numerical model and based on a worst-case scenario predicted its extinction by 2100. What is it in reality?
The government site establishes the world population between 22,000 and 31,000 animals divided into 19 subpopulations. Canada alone is home to nearly 16,000, 90% of which are concentrated in the northernmost regions, Nunavut and the Northwest Territories. They are also found in Denmark (Greenland), Norway and Russia, as well as in Alaska. The majority of the subpopulations would be stable or slightly increasing, but some further south would be in decline. It should be noted that censuses are difficult to carry out and involve a large degree of uncertainty.
In the 1960s, the world population fell to some 5,000 due to overhunting. In 1973, the five circumpolar countries concluded an agreement providing for the regulation of sport hunting, the prohibition of certain practices and the protection of ecosystems important to the polar bear. In 2015, a Circumpolar Action Plan was adopted to protect the species.
In Canada, polar bear hunting is the responsibility of the Inuit, for whom it has both cultural and economic importance. The Fur Institute of Canada ensures that the species is not currently threatened and that controlled hunting does not constitute a risk to its survival. Some 600 animals are taken each year, or 3% of stocks.
The polar bear and the grizzly both derive from a common ancestor, the brown bear, and remain genetically very close. Hybridizations known as pizza and grolar have been observed both in the wild and in captivity. The polar bear would have started to differentiate some 1.3 million years ago.
If today it is well adapted to polar conditions, it should be noted that these conditions are anything but stable. Approximately every 100,000 years, a large part of the northern hemisphere is covered with a mantle of ice, the thickness of which can exceed several kilometres. These glacial periods are interspersed with relatively warm periods called interglacials, such as the current Holocene which began 11,700 years ago and which has seen strong, sometimes very abrupt, temperature fluctuations.
Today, the polar bear feeds mainly on seals that it hunts from the pack ice, especially in the spring. The latter bottoms in summer, reaches its minimum extent in September and then recovers in autumn. The area of the Arctic sea ice decreased sharply from 1980, but it is currently in the process of stabilization.
Additionally, a study published in November 2021 (Mechanisms of the Early 20th Century Warming in the Arctic) shows that the warming of the early 20e century was comparable in magnitude to the current warming. Note also that it was considerably warmer during the Optimum of the Holocene, 6000 years ago.
In short, the polar bear is an extremely adaptable and resilient species that has survived many significant climate changes.
Robert Girouard, science communicator