The recent study showed the impressive loss of the Greenland ice sheet in 2019, says the article published today in The Cryosphere. In fact, the 2019 loss becomes the second-highest amount of runoff from melting ice, while 2012 was worse.
In 2019, Greenland ice has been melting much faster than ever, the glaciologists found. In other words, the ice sheet brought the biggest drops in surface mass balance since record-keeping began in 1948. Surface mass balance takes into account gains in the ice sheet’s mass — such as through snowfall — as well as losses from surface meltwater runoff.
The year 2019 was one of the worst years on record for the Greenland ice sheet, the scientists confirmed. The ice shrunk by hundreds of billions of tons, according to lead author Marco Tedesco from Columbia University’s Lamont-Doherty Earth Observatory.
The reason for such unbelievable loss of ice sheet is climate changes. Unfortunately, the current climate models may be underestimating future melting by about half, the glaciologists suggest. The study used satellite data, ground measurements, and climate models to analyze changes in the ice sheet during the summer of 2019.
“You can see the mass balance in Greenland as your bank account,” said Tedesco. “In some periods you spend more, and in some periods you earn more. If you spend too much you go negative. This is what happened to Greenland recently.”
Before now, 2012 was Greenland’s worst year for surface mass balance, with a loss of 310 billion tons compared to the 1981-2010 baseline. Yet summer temperatures in Greenland were actually higher in 2012 than in 2019 — so why did the surface lose so much mass last year?
Tedesco and co-author Xavier Fettweis, from the University of Liège, found that the record-setting ice loss was linked to high-pressure conditions (called anticyclonic conditions) that prevailed over Greenland for unusually long periods of time in 2019.
According to the theory, through these combined effects, the atmospheric conditions of the summer of 2019 led to the highest annual mass loss from Greenland’s surface since record-keeping began.
Meantime, Tedesco and Fettweis found that 2019’s large number of days with these high-pressure atmospheric conditions was unprecedented. The summer of 2012, one of Greenland’s worst years, also saw anticyclonic conditions.
The most alarming signal is the current global climate models are not able to capture these effects of a wavier jet stream. So, simulations of future impacts are «very likely underestimating the mass loss due to climate change,” Tedesco explained and added that it’s almost like missing half of the melting.