End of the polar bear?

Species could be wiped out in 80 years as melting ice forces them ashore

At risk: Polar bears could be wiped out

The polar bear population would be forced on to land if there is no ice left to use to hunt seals.

They would then have to rely on their fat reserves which would threaten the survival of the species, researchers said.

The study, published in the journal Nature Climate Change, said there must be ‘aggressive’ cuts to greenhouse gas emissions to save the animals, which rely on sea ice to reach their prey, from extinction.

Researchers used modelling to determine a polar bear’s energy requirements while fasting and what threshold would need to be reached to limit their survival, along with a model to predict the future number of ice-free days. This was then used to estimate when the survival thresholds would be surpassed for 13 Arctic sub-populations, representing 80 per cent of all polar bears.

Study author Peter Molnar and his colleagues found that, under a high greenhouse gas emissions scenario, the bears’ survival would be ‘unlikely’ over much of the Arctic due to reduced sea ice.

But under a ‘moderate emissions scenario’, more sub-populations could survive this century. The report said: ‘Ultimately, aggressive greenhouse gas emissions mitigation will be required to save polar bears from extinction.’ Professor Molnar, a biological scientist at Toronto University in Canada, added: ‘Polar bears are already sitting at the top of the world; if the ice goes, they have no place to go.’

Researchers found that cubs would be most at risk from fasting, while solitary adult females would be the least affected.

It also found that survival thresholds may have already been reached in several polar bear sub-populations.

The authors added: ‘ Our model captures demographic trends observed during 1979 to 2016, showing that recruitment and survival impact thresholds may already have been exceeded in some 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 highArctic sub-populations by 2100.’

The global polar bear population is estimated at around 26,000, with some 16,000 of these in Canada. In the southernmost area of the Arctic the bears are forced ashore each summer.

They rely on body energy reserves for survival and lactation due to the absence of adequate food.

While the marine mammals can fast for months, lengthening periods have already lowered body condition, reproduction, survival and abundance.

It is still unclear how long the bears can go without food before substantial declines in lactation and therefore ‘cub recruitment’ and adult survival occur.

‘They have no place to go’

MELTING sea ice in the Arctic could wipe out most polar bears by the end of the century, according to research.