Recently, an article in the National Geographic once again addressed the serious situation polar bears are facing. The article consists of a report on the effect of global warming, which becomes more of a threat to the animal’s natural habitat with every passing day.
Source: Ralph Lee Hopkins, National Geographic
In December 2017, the magazine published a harrowing video which showed a skeletal polar which was starving as a result of a lack of natural sustenance in its territory. This shortage of food was caused by melting ice, which prevents the bear from hunting seals, its main source of calories.
Source: Screen shot from Paul Nicklen and Christina Mittermeier's video for Sea Legacy
While scientists have often dismissed the possibility of a link between melting ice and starving polar bears, this new article attempts to rekindle the debate by involving scientific discoveries from several experts.
Thanks to researchers who have studied the issue of the disappearance of polar bears, there is now greater awareness of it, and we can now establish a line of cause and effect between global warming and the lower numbers of polar bears.
Source: Paul Nicklen, National Geographic
First and foremost, wildlife biologist Anthony Pagano has highlighted the fact that the polar bear has a very particular metabolism in comparison to other vertebrates. A study led by the researcher revealed that this particular kind of bear needs around 60% more food than was believed until now. Curiously, polar bears burn calories much faster than most mammals (between 12,000 and 32,500 each day). This seems surprising, given that polar bears aren’t particularly active, and spend most of their time walking or sleeping.
Source: Norbert Rosing, National Geographic
Furthermore, according to Andrew Derocher, a renowned polar bear expert from Canada, these mammals “aren’t made for walking”. They can lose weight very quickly, and burn even more calories while swimming. The problem lies in the fact that nowadays, polar bears are burning fat faster than they can put it on; the reason being that their main food source - seals - is becoming harder and harder to come by.
As shown by the studies led by National Geographic, these animals depend heavily on seals for sustenance. As a prey animal, seals are very rich in calories, and when eaten quickly satisfy the bear’s appetite and replenish its fat stores. Most of the time, polar bears hunt while sitting down. They lie along an ice bank and wait for seals to poke their head out of the water in order to catch them. This technique requires little effort, and allows the bear t conserve calories.
Source: National Geographic
If these bears are having such difficulty procuring food today, the reason lies before our eyes. The melting of the polar ice caps, brought on by global warming, reduces the number of seals by the ice banks - and it turn the amount of food available to polar bears.
The Arctic - the polar bear’s natural habitat - is the region most affected by global warming. Nowadays, satellites show that between 1981 and 2010, the surface of the ice has shrunken by around 2 million square kilometres (77,000 square miles). As noted by National Geographic, this is the size of both Alaska and California put together.
Source: Paul Nicklen, National Geographic
It now seems that the ice is melting at a faster rate than previously, and that it is reforming more slowly. As a result, polar bears are forced to cross long distances by foot or in the water in order to find ice and, by extension, food. In some cases, they prefer to save energy and fast for part of the summer and autumn, living on fat reserves accumulated during the spring.
Source: Paul Nicklen, National Geographic
In the course of his study, Pagano was also able to capture several male and female polar bears in order to fit with with GPS tracking, and to take blood and urine samples. Once the data was collected, Pagano noticed that the bears hadn’t travelled very far, but had still burnt a large quantity of fat. During the ten-day observation period, some bears lost up to 20 kilos (45 pounds).
Source: Paul Nicklen, National Geographic
Steven Amstrup, a scientist for Polar Bears International, said of the study:
It’s a really strong study. It shows that polar bears are more like the big cats—lions and tigers— predatory carnivores with high energy metabolisms.
Polar bears are currently listed as an endangered species by the International Union for Conservation of Nature (IUCN). Their natural habitat is seriously under threat, and global warming is the main cause."
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