At a Glance

At one point, older sea ice made up 30 percent of the sea ice within the Arctic Ocean.Today, nearly all of the older sea is gone, replaced by newer, thinner, more vulnerable sea ice. Arctic sea ice extent also just reached an all-time low for the month of April.

Nearly all of the older Arctic sea ice is gone, making the ice sheet even more vulnerable to storms and the impacts of global warming, a new report of the National Snow and Ice Data Center says.

In years gone by, four-year-old or older sea ice made up within the Arctic Ocean. Today, nearly all of the older sea ice is gone, replaced by newer ice that is thinner and therefore more susceptible to climate change, according to the agency's report published this week.

The loss of older sea ice makes the ice sheet more vulnerable to global warming because it breaks up more easily under the onslaught of storms and melts more quickly in warming waters.

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The researchers did offer a slim glimmer of hope that the summer melt will not entirely wipe out all of the older sea ice.

"As of mid-April 2019, the 4-plus-year-old ice made up only 1.2 percent of the ice cover. However, 3- to 4-year-old ice increased slightly, jumping from 1.1 percent in 2018 to 6.1 percent this year," the authors wrote. "If that ice survives the summer melt season, it will somewhat replenish the 4-plus-year-old category going into the 2019 to 2020 winter. However, there has been little such replenishment in recent years."

Monthly April ice extent for 1979 to 2019 shows a decline of 2.64 percent per decade.

(National Snow and Ice Data Center)

The report had more bad news to share for the beleaguered Arctic ice sheet, noting that the roof of the world's sea ice extent set a new April low that surpassed the previous record set in April 2016.

"Arctic sea ice extent for April 2019 averaged 5.19 million square miles. This was 479,000 square miles below the 1981 to 2010 long-term average extent and 89,000 square miles below the previous record low set in April 2016," the authors wrote.