Global Warming and Polar Bear - how are they related?
Updated: Dec 26, 2020
Is global warming real?
Yes, it is true. Throughout our earth's history, the climate fluctuates; there are seven periods of glaciers growing and shrinking. The last ice age ended 11 700 years ago and, after it, started the current cycles of natural global warming and cooling. The natural rhythm of climate change is contributed by the small variation of the earth's orbit, which allows the planet to receive a different amount of energy from the sun.
However, the rapid warming we encounter now cannot be explained by the natural cycles. With the advancement of technology, scientists can provide plenty of evidence supporting global warming:
The increase in the earth's average surface temperature: since the last century, the temperature has risen 1.14 degrees Celsius. This change that is supposed to spread throughout hundreds of thousands of years now happens within decades. The global temperature hit a record high, with 19 out of 20 warmest years recorded since 2001.
The rise in the ocean surface temperature: the ocean acts as the planet heat modulator has shown 0.33 degrees Celsius increase in temperature. The temperature increases cause the melting of ice shelves and sea ice. Satellite data showed a loss of 279 and 179 million tons of ice shelves in Greenland and Antarctica per year respectively. Also, satellites record a 13 % decline in Arctic sea ice per decade from 1981 to 2010.
The decrease in inland ice and snow cover volume: satellite data report the shrinking of land ice sheets in the Antarctic, Greenland since 2002, and glaciers are diminishing all around the planet, including Alaska, the Himalayas, and Africa. Also, the snow cover on the mountains’ peaks in the Northern hemisphere are decreasing since five decades ago and the snow is melting earlier in spring.
The rising of sea level: The sea level rises 8 inches since 1880, the rise is due to two factors: the melting of ice from the land, which included inland ice sheets and glaciers flowing into the ocean. And the surface seawater expands as a result of increased temperature.
The increase in extreme weather. The increases in episodes of intense rainfall and storms are fuels by warm and wet air.
Increase in atmospheric carbon dioxide level and acidify seawater: atmospheric carbon dioxide level has increased sharply since 1950, coinciding with the industrial revolution. The excessive emission of carbon dioxide by humans is absorbed by the ocean. As a result, causing the increased acidity of ocean water by 30 %.
What is the relationship between melting sea ice and Polar Bears?
The diet of polar bears
Polar bears sit and wait for their prey most of the time in a day is, in fact, high metabolic carnivores. A polar bear requires at least 12 325 calories per day and its diet depends heavily on seals.
The most efficient way for a polar bear to capture a seal is still hunting. He or she waits on the ice until a seal emerges its head from the water to breathe; the polar bear bites on the seal's neck and flips it on the ice. The polar bear will feed on the seal's skin and blubber first (for high-fat content), followed by the meat. A ringed seal weight up to 55kg can provide as much as 8 days of energy reserve to the bear.
What happened to the polar bears when the amount of sea ice decreased?
Polar bears are forced to swim or walk long distances to capture their food. The bears are good distance swimmers but too much swimming is endangered to them. A polar bear mother loses 22% of her body weight and her cubs in a long-distance swam. Prolonged walking is even worse for the bears as they are inefficient walkers than swimmers. Polar bears starve during long-distance travel to get their food, which decreases their lean muscle mass and hence the chance of a successful hunt.
Ice forms later in autumn and melts earlier in spring, giving polar bears a shorter time hunting for food.
More problematic for polar bear cubs to survive. As their mothers require to travel a long distance to build the dens on land for their cubs and those shelters are more easily to collapse in warmer weather. Also, reducing sea ice forces young polar bears to swim further before they are ready.
Don't forget the decrease in sea ice also affects the seals as they rely on the sea ice to raise their offspring.
The impact of climate change on polar bear
Climate change is the most significant impact encounter by the polar bears and it is bigger than we previously thought. One previous study in the Beaufort Sea region had estimated a decrease of 40% in the polar bear population in the last decade. If sea ice continues to decline, there will be a 70% chance that polar bears will decrease by 30% within three generations, estimated by scientists.
Can polar bears adapt to climate change?
Some may think according to Darwin's theory, animals and plants will adapt. Or some may argue that in recent research in 2016, scientists found a slight increase (+130) in polar bears in the Baffin Bay and Kane Basin. However, researchers suggested that the changes may due to the decreases in hunting and it is doubtful that the difference in sampling techniques contributed to the rise.
The polar bear expert from the University of Washington, Dr. Eric Regehr, claimed that the Baffin Bay and Kane Basin studies "certainly don't lead to the conclusion polar bears are fine in relation to climate change."
It is hard for the polar bears to catch up with rapid climate change. Shall we, the homo sapiens (main contributor of global warming), work together no matter big or small, do a little favor to all of the planet's species?
As the IUCN Species Survival Commission coordinator, Dena Cator, said, "The single most important factor to improve the long-term survival of polar bears is reducing greenhouse gas emissions and stabilizing Arctic sea-ice."
know more about how polar bear affect biodiversity
Polar bear questions and answers
For your fact check:
WWF 10 myths about climate change
Sea World Parks and Entertainment: polar bear diet
Carbon Brief: polar bears and climate change
National Geographic: polar bears and climate change
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