Greenland’s unusually mild summer in 2019 caused the world’s largest island to lose 600 billion tons of ice in just two months, rivaling the summer of 2012 for the most ice mass lost in a single melt season, according to NASA data released Wednesday.
“We knew this past summer had been particularly warm in Greenland, melting every corner of the ice sheet, but the numbers are enormous,” said lead author Isabella Velicogna, an Earth science professor at the University of California at Irvine and a senior scientist at NASA’s Jet Propulsion Laboratory, in a news release.
The mass loss from Greenland alone was enough to raise global sea levels by 2.2 millimeters, the study found.
Study confirms new satellite mission is working
The data, published in the journal Geophysical Research Letters, also find measurements from a new satellite system, known as the Gravity Recovery and Climate Experiment Follow-On mission (GRACE-FO), are consistent with the previous incarnation of gravity-sensing satellites, known simply as GRACE, which went out of service in 2017. This extends the satellite-based ice mass loss record to 17 years, beginning in March 2002 and including a minor gap in data sets.
The GRACE-FO satellites are able to sense tiny changes in Earth’s gravitational field caused by ice sheets gaining or losing mass and have proved useful in studying groundwater storage worldwide.
Between 2002 and 2019, across the full time series of both satellite missions, the study finds Greenland lost 4,550 billion tons of ice, or an average of about 261 billion tons per year.
In an interview, Velicogna said the data clearly show 2019 was a major melt year in Greenland, and what distinguishes it from previous big ice-loss years is the significant melting that occurred in glaciers in the northern and northeastern regions.
“There is a significant [melt] component also coming from the north and northeast of Greenland. And so, basically, we have the loss all around the ice sheet,” she said.
Yara Mohajerani, a study co-author from UC Irvine, said persistent high-pressure areas, as well as low cloud cover in northern Greenland, caused ice losses there to spike last year.