Story at a glance
- In 2019, researchers found that Greenland's ice sheet was melting seven times faster than it was in 1990.
- Unusually clear skies contributed to the rapid melting, a new study study finds, in addition to warm temperatures.
- The research suggests that current models could be underestimating future melting by about half.
Last year, scientists found that Greenland's ice is melting seven times faster than it was roughly 30 years ago, putting the planet on track for the worst-case sea-level rise scenario predicted by climate projections.
Now, a new study suggests the melt isn't slowing down anytime soon.
“Simulations of future impacts are very likely underestimating the mass loss due to climate change,” said Marco Tedesco, lead author of the study. “It’s almost like missing half of the melting.”
The study analyzed changes in the ice sheet during the summer of 2019 to understand what caused the largest drop in surface mass balance since record-keeping began in 1948. Surface mass balance reflects both gains in mass, including from snowfall, and losses throughout the year.
“You can see the mass balance in Greenland as your bank account,” said Tedesco in a release. “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.”
In 2019, the ice sheet’s surface mass balance dropped by about 320 billion tons below the average for the years 1981 through 2010. But it wasn't the hottest year in that range — in fact, summer temperatures in Greenland were actually higher in 2012 than in 2019.
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It turns out that there’s more to the loss of ice than warmer weather. Unusually clear skies in the south of Greenland contributed to the ice sheet's rapid loss of mass, both allowing more sunlight in and limiting the amount of snowfall. At the same time, warm and moist clouds in the northern and western parts of Greenland trapped the heat radiating off the ice, creating a small-scale greenhouse effect.
“Imagine this vortex rotating in the southern part of Greenland,” Tedesco explained, “and that is literally sucking in like a vacuum cleaner the moisture and heat of New York City, for example, and dumping it in the Arctic — in this case, along the west coast of Greenland. When that happened, because you have more moisture and more energy, it promoted the formation of clouds in the northern part.”
These high-pressure atmospheric conditions have become more frequent over the past few decades, Tedesco said. But current global climate models don’t reflect these changes, which means Greenland’s ice sheet, which contains enough frozen water to raise sea levels by as much as 23 feet, is melting much faster than the world is prepared for.
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