Daily Mirror (Northern Ireland)
Fall of the wild13
Polar bears will become extinct in 80yrs if global warming continues
MELTING sea ice could jeopardise the survival of polar bears by 2100, a study claims.
As the Arctic is warming twice as rapidly as the global average, it diminishes the sea ice the creatures use as hunting grounds to catch seals.
Researchers from the University of Toronto in Canada said a loss of sea ice caused by global warming will force the animals on to land, where they must rely on fat reserves due to a lack of food.
Weighing as much as 10 adults, polar bears pose a huge threat to people if forced into contact with them.
The study, published in Nature Climate Change, said “aggressive” cuts to greenhouse gas emissions are now needed if the world’s largest land predators are to be saved from extinction.
There are thought to be as few as 22,000 polar bears left in the world. Researchers worked out a polar bear’s energy requirements while fasting and the thresholds that would limit its survival, and used a mathematical model to predict the number of ice-free days in the future.
This was then used to estimate when the survival thresholds would be surpassed for 13 Arctic sub-populations, which together represent 80% of the world’s polar bears.
Study author Peter Molnar and his colleagues found that, in a high greenhouse gas emissions scenario, the bears’ survival would be “unlikely” past 2100 over much of the Arctic due to reduced sea ice. However, under a “moderate emissions scenario”, more sub-populations could survive the end of this century.
The study says: “Ultimately, aggressive greenhouse gas emissions mitigation will be required to save polar bears from extinction.” Mr Molnar said that while the findings may seem “just another polar bear doom and gloom story”, research shows cutting emissions “can make a difference”. He added: “There is no alternative way.” Researchers found that cubs would be most at risk from fasting, while solitary adult females would be the least-affected polar bear demographic.
It also found that several populations may be close to dying out already.
The authors write: “Our model captures demographic trends observed during 1979 to 2016, showing that recruitment and survival impact thresholds may already have been exceeded in some [polar bear] sub-populations.
“It also suggests that, with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardise the persistence of all but a few high-arctic sub-populations by 2100.”
The authors note that their study was limited by the use of a single “earth systems model” – used to determine how sea ice will be affected – and is subject to uncertainties and variations in bear behaviour and energy usage among different bear populations.
A study earlier this year found that the environmental impacts of climate change are causing polar bears to lose weight and have fewer offspring.
Researchers at the University of Washington found the bears spent 30 more days on land between 2009 and 2015 than they did in the 90s as sea ice melted at a faster rate.