Polar bear decline has been happening for 20,000 years: study

By Isobel Williams via SWNS

Polar bears have been in decline for 20,000 years, a new study reveals.

The revelation that this has been taking place for so long was discovered by the University of Copenhagen when they studied the bears' DNA and diet.

Over the last 20,000 years, the polar bear population in Greenland has reduced by 20 to 40 percent due to rising sea temperatures.

They believe that polar bears could be extinct in Greenland within 50 years.

Professor Eline Lorenzen said: "By analyzing the genetic material from the polar bears, we can open a window into the past and gain an insight into the species' development history and population history.

“Our analysis reveals that the number of polar bears has been significantly reduced several times since the last ice age."

Lead author assistant professor Michael Westbury believes this decline is due to the rising sea temperatures caused by climate change, which have eliminated the bears' food source.

He said: "It's the rising sea temperatures that drive the decline in the polar bear population.

"When the sea temperature rises, there is less sea ice, and consequently, fewer seals, which polar bears feed on.

"We see a disturbing connection between population decline and environmental changes.

“A relatively small increase in water temperature and a small reduction in the amount of sea ice result in a quite dramatic decline in the polar bear population. The relationship is not linear."

This small change in sea temperature was around 0.2 to 0.5 degrees over the span of 20,000 years.

If this small change caused a population decrease of around 40 percent in Greenland’s polar bears, scientists are very concerned about how the species will survive the expected 2-5 degree increases to come.

Professor Westbury continued: "The current development is unprecedented compared to what the polar bear has experienced over the last 20,000 years.

"And with the drastic projections, we can expect that the species will not thrive at all."

Professor Lorenzen added: "Looking ahead, we are potentially facing a two to five-degree increase in sea temperatures around Greenland.

"So, it's a tenfold increase in temperature changes compared to the last 20,000 years.

“It doesn't look good for the polar bear. And as the top of the food chain, the polar bear represents ecosystem changes more generally, showing that marine ecosystems in the Arctic are under pressure.

"It's all of us. The Earth is a large, interconnected ecosystem, of which we are an integrated and deeply dependent part. Nature knows no boundaries."

However, there is still hope for the bears as they are known for being able to change and adapt their eating habits which may help them adjust to climate change.

In East Greenland, Polar bears differentiated what they ate to avoid competition with males consuming various seal species, while females eat ringed seals.

Scientists hope that when sea levels rise again the Greenland polar bears will be able to adjust their diet to survive once again.

Their full research was published in the journal Science Advances.