Greenland loses 2 billion tons of ice in one day

Greenland loses 2 billion tons of ice in one day
Christian Streib/CNN
Greenland's massive ice sheets contain enough water to raise global sea levels by 23 feet, and a new study shows that they are melting at a rate "unprecedented" over centuries -- and likely thousands of years.

Over 40% of Greenland experienced melting Thursday, with total ice loss estimated to be more than 2 gigatons (equal to 2 billion tons) on just that day alone.

While Greenland is a big island filled with lots of ice, it is highly unusual for that much ice to be lost in the middle of June. The average “melt season” for Greenland runs from June to August, with the bulk of the melting occurring in July.

To visualize how much ice that is, imagine filling the National Mall in Washington with enough ice to reach a point in the sky eight times higher than the Washington Monument (to borrow an analogy Meredith Nettles from Columbia University gave to The Washington Post).

The sudden spike in melting “is unusual, but not unprecedented,” according to Thomas Mote, a research scientist at the University of Georgia who studies Greenland’s climate.

“It is comparable to some spikes we saw in June of 2012,” Mote told CNN, referring to the record-setting melt year of 2012 that saw almost the entire ice sheet experience melting for the first time in recorded history.

This much melting this early in the summer could be a bad sign, indicating 2019 could once again set records for the amount of Greenland ice loss.

Mote explained how snow and ice melt off the Greenland ice sheet, especially early in the season, makes it easier to for additional melt to occur later in the summer.

White snow and ice, which is bright and reflects the sun’s rays back into space, reduces the amount of heat that is absorbed and helps to keep the ice sheet cold, a process known as “albedo.”

“These melt events result in a changed surface albedo,” according to Mote, which will allow more of the mid-summer sun’s heat to be absorbed into the ice and melt it.

Predictions for a record melt season

Mote says “all signs seem to be pointing to a large melt season,” and he is far from the only scientist to think so.

Jason Box, an ice climatologist at the Geological Survey of Denmark and Greenland, predicted in late May that gtx_ads_conf.ads["ad-manager-551125"]= {"custom_css":"","ad_details":[{"min_width":"","max_width":"","dfp_ad_sizes":[{"dfp_ad_width":"300","dfp_ad_height":"250"}]}],"ad_id":551125,"ad_container":"div-ad-manager-551125","ad_placement":"in-article","ad_name":"ad-manager-551125","position":"in_article","article_position":3};

If these extreme melt seasons are becoming the new normal, it could have significant ramifications around the globe, especially for sea level rise.

“Greenland has been an increasing contributor to global sea level rise over the past two decades,” Mote said, “and surface melting and runoff is a large portion of that.”