ice over

Though polar bears are usually born on land, they spend most of their lives on ice over the arctic seas.

It is much rarer for these polynyas to form in sea ice over the open ocean, hundreds of kilometres away from the coast where the seas are thousands of meters deep.

High temperatures have contributed to a loss of glacier ice on the continent, including in the Alps — which have lost about 10% of their remaining glacier ice over the last two years.

Finally, there is another study from PNAS, this one about how Arctic sea life has responded to the loss of 1 million square kilometers of sea ice over the past 25 years.

To learn this, the researchers drilled a 651-meter-long ice core from Skytrain Ice Rise in 2019, which formed as layers of snow falls and turns into ice over thousands of years.