Despite what some may think, polar bear scientists never set out to make their study species the “poster species” for climate change. It was possibly preordained by the 1973 Agreement on the Conservation of Polar Bears , signed by the five Arctic nations with bears in their jurisdiction, which obliged each of the signatory nations to conduct national research programs on polar bears. The resulting legacy of scientific data created a depth of understanding of polar bear ecology that surpasses other Arctic species and most large carnivores. And yet, years later, as the COP21 Paris agreement transitions into policy, polar bears still face a challenging future.
Early on in their research programs, it became clear that polar bears rely on sea ice. The ongoing melting of the Arctic sea ice and projections provided by climate scientists served as the catalysts for polar bear scientists to explore the links between anthropogenic warming and the melting of the polar bears’ habitat. This was a logical conservation concern: Habitat loss – tropical forests, grasslands, wetlands and, yes, sea ice – is the single largest threat to mammals around the world.
The first scientific study exploring a link between climate warming and polar bears was published in 1993, relatively early in the biological exploration of the consequences of unbridled carbon emissions. Studies since then present a consistent picture, despite the ranting of climate change deniers.
When it comes to the science of polar bears and the effects of climate change, we have a profound understanding of how the bears are affected. It’s a very simple story with clear scientific evidence. Sea ice is the primary habitat of polar bears. They rely on the sea ice to migrate and it is where they feed, mate and, in some areas, den to produce their young.
A warming Arctic has less sea ice and this loss is projected to continue unless we control greenhouse gas emissions. The Arctic is warming faster than southern latitudes, so the changes are coming sooner for polar bears than for most other species. At some point, the sea ice will melt too early and form too late for polar bears to persist: The fasting period on land will become too long and, consequently, both survival and reproductive rates will drop too low to sustain a population.
Fanciful predictions of polar bears becoming more terrestrial aren’t likely and, besides, nature did this experiment for us at the end of the last ice age 10,000 years ago. When the ice began to recede, polar bears in southern Scandinavia didn’t become more terrestrial, they migrated northward, leaving behind plenty of fossil evidence that they had been there.
Today, polar bears can’t move farther north over the deep and unproductive waters in the Arctic Basin. Polar bears make their living from the shallow continental shelves where marine productivity is high. Furthermore, the Arctic Basin is predicted to become ice-free in summer and is unlikely to ever support an ecosystem vibrant enough to sustain a viable population of polar bears.
How do we know what is enough sea ice for polar bears? Scientists across the Arctic have studied the bears intensely, documenting their movements and migrations in relation to sea ice to provide a clear picture. We can determine the date that bears move onto the sea ice and the date they return to land. We understand how their fat stores vary with the dates of sea ice break-up and freeze-up. If the ice-free period is too long, the bears exhaust their fat stores, can’t replenish them by hunting seals and, eventually, the area can’t support polar bears.
The iconic status of polar bears reaches beyond science, and likely resides deep in our co-evolution with bears as early humans expanded across the globe. Humans have always competed with bear species for food and space. Due to this closeness, bears – and polar bears in particular – have emerged as culturally significant species. That the bears are drop-dead gorgeous doesn’t hurt either. Couple these good looks with the lifestyle of a committed carnivore that strips energy-rich blubber from seals, and we have the original beauty and the beast all in one.
The warming we’re bound to has sealed the fate of most polar bears. But if we act wisely and boldly, perhaps we can hold onto some wild polar bears in the high latitudes of the Canadian Archipelago and northern Greenland. We can help the bears by slowing the rate of Arctic warming, reducing sources of mortality and protecting the areas that the bears need. We may even have to start feeding polar bears to sustain their numbers until the planet cools.
If things go well, the bears can wait until the planet cools down and move back south in the future.
The failure to deal with climate change has been our collective failure. As humans, we can correct our failures if we learn. The fate of all polar bears, however, is dependent on how all of us learn and our willingness to respond to a challenge greater than any previously faced by polar bears and humanity at large.
Most polar bear scientists are not advocates for polar bears: Really, they’re much more advocates for polar bear science. Nonetheless, it would be a heartless scientist who didn’t care about the generations to come – and the future generations of polar bears that should still be infusing our imaginations, art and history.
The views expressed in this article belong to the author and do not necessarily reflect those of Arctic Deeply.
Top image: Two young adult male polar bears play fight in November 2015 near Churchill, Manitoba, while waiting for the sea ice to form. (Andrew E. Derocher)