Numerous polar bear populations are in danger of disappearing due to climate change.
The earth is heating up. Temperatures are rising rapidly, especially in the Arctic. Among other things, it results in melting sea ice. Previous studies have already shown that this is a major problem for the polar bear, which hunts seals from that sea ice. In a new study, scientists looked at how the disappearance of the sea ice is exactly changing the future of the polar bear. And it does not look good, according to the journal Nature Climate Change . If global warming continues at this rate, most polar bear populations will collapse by the end of this century.
The polar bear diet consists mainly of seals. And those seals can only catch the polar bears from the sea ice. Because the sea ice decreases much more than normal during the summer, polar bears are forced to leave the sea ice and flee to land. However, nothing can be achieved there. It means that polar bears eat less, and as the Earth warms, they cannot take any food at all for increasingly long periods of time.
“The problem is that sea ice will continue to disappear as long as the Earth warms,” says researcher Péter Molnár. “That means polar bears have to do without food everywhere for extended periods of time and that affects their reproduction, survival rates and the survival of healthy populations.”
In their study, the researchers determine how many days in a row polar bears can do without food and at the same time manage to raise their young and stay alive. Then, using climate models, they look at how long polar bears are unlikely to have access to sea ice and thus food in future years. By combining that data, the researchers can determine when polar bears’ survival chances are really compromised and polar bear populations are about to collapse.
The research paints a somewhat rosy picture. If global warming continues at the current rate, the researchers say we can expect that the survival and reproduction chances of almost all polar bear populations will decrease enormously. And most populations will disappear by the end of this century. “Although our predictions about the future of polar bears are terrible, unfortunately they are probably still too optimistic,” said Molnár. “For example, we assumed (in our study, ed.) That polar bears make optimal use of their available body energy when they fast. If not, reality can be much worse than our predictions. ”
In their study, the researchers looked at polar bear populations that together make up 80% of the total population. The polar bears that inhabit the Canadian Arctic Islands – making up 20% of the global population – were disregarded because there was not enough data available. However, the researchers suspect that these polar bears face the same fate as the populations studied.
But the predictions don’t have to come true, the researchers also emphasize. In their study, they assume a situation in which warming continues. By reducing our emissions, we can limit global warming and the impact it has on polar bears. “We found that a small reduction in emissions causes polar bears to last longer,” said researcher Steven Armstrup. “But it probably won’t prevent quite a few populations from disappearing, and that just goes to emphasize the importance of being much more ambitious when it comes to reducing our emissions.” For example, polar bears in their current habitat would have an indefinite right to exist if we succeed in limiting global warming to 2 degrees Celsius.