One of the most critical times for polar bears to have enough body fat is during lactation, when they nurse their cubs in a snow den.
Female polar bears usually give birth to two cubs every two to three years, and they stay with them in the den for about four months, without eating or drinking.
During this time, they rely solely on their body fat to produce milk for their cubs, which can consume up to 2 liters of milk per day.
The quality and quantity of polar bear milk depends on the mother's body condition, which is influenced by the availability of sea ice and seals.
Studies have shown that polar bear milk is very rich in fat (up to 31%) and protein (up to 11%), and that it varies seasonally and geographically.
Polar bear milk is also one of the most contaminated animal milks in the world, due to the accumulation of pollutants in the Arctic food chain.
If sea ice declines, polar bears may have less access to seals and less time to hunt them, resulting in lower body fat reserves and lower milk production.
This could affect the growth and survival of their cubs, as well as their ability to reproduce in the future.
What are the impacts of climate change on polar bear populations?
Climate change is having a clear negative impact on polar bears, say scientists, making it harder for them to hunt, mate and breed.
Polar bears live in 19 key regions across the Arctic, all of which have experienced some degree of ice loss.
According to the International Union for Conservation of Nature (IUCN), polar bears are classified as vulnerable, with a high risk of extinction in the wild.
The IUCN estimated that there are between 22,000 and 31,000 polar bears in the world, but this number is uncertain and may be declining.
Some polar bear populations have already shown signs of decline, such as those in the Southern Beaufort Sea and Western Hudson Bay.
Polar bears have shown some ability to adapt to changes in their environment, such as by foraging for food on land, or swimming more to hunt for prey.
However, these adaptations may not be enough to cope with the rapid and widespread loss of sea ice projected for the future.
Scientists predicted that as sea ice diminishes, polar bears will find it harder to survive and populations will decline.
What can be done to protect polar bears from climate change?
The most effective way to protect polar bears from climate change is to reduce greenhouse gas emissions and slow down global warming.
This would help preserve the sea ice ecosystem that polar bears rely on for their survival. However, this requires global cooperation and action from governments, businesses and individuals.
In addition to reducing emissions, there are other measures that can be taken to help polar bears cope with climate change. Some of these include:
Identifying and protecting the "last ice areas", the parts of the Arctic that are projected to retain sea ice farthest into the future. These areas could serve as refuges for polar bears and other wildlife that depend on sea ice.
Increasing monitoring of polar bear populations, particularly their responses to declining sea ice. This would help improve scientific knowledge and inform conservation decisions.
Managing human-polar bear conflicts, which may increase as polar bears spend more time on land. This would involve educating local communities, implementing deterrents and coexistence strategies, and enforcing regulations.
Combating other threats that affect polar bears, such as poaching, pollution, oil spills and habitat fragmentation. These threats could exacerbate the effects of climate change and reduce the resilience of polar bears.
Polar bears are remarkable animals that have adapted to one of the most extreme environments on Earth.
However, they are facing unprecedented challenges from climate change that threaten their existence.
By taking action now, we can help ensure that these magnificent creatures continue to thrive in the Arctic for generations to come.
