A new study of Greenland’s ice sheet shows that very little precipitation on the island’s expansive interior is “lost to the atmosphere through evaporation” because of the island’s unique thermal “lid.” This remarkable thermal lid essentially prevents any snow and ice from escaping the island via evaporation, allowing the ice sheet to continuously build up on the island. Funded by the National Science Foundation, the study was published in the open access online-only journal “Science Advances.” This is more evidence that Greenland’s ice sheet is robust and stable, even though computer models claimed it would be the first casualty in a warming world.
Some may recall that in Al Gore’s “An Inconvenient Truth (2006),” he said that a sea level rise of up to six meters (20 feet) would happen from the melting of either West Antarctica or Greenland or both. Using PowerPoint slides, the former vice president showed various cities being submerged from this cataclysmic thawing event, even though Greenland’s ice sheet survived the last three interglacial periods where temperatures were five degrees Celsius warmer than today. Other studies have also shown that the geologically active Antarctica is gaining in size, but this first-of-its-kind study adds more cold water to the already heated rhetoric on Greenland’s so-called imminent melting.
Based on new measurements from a research tower on the Greenland ice sheet, the study’s authors uncovered how snow piles up on the ice sheet year after year. According to the study’s principal investigator David Noone, an Oregon State University professor and atmospheric scientist, he says: “Normally, the air temperature goes down as you climb, but near the surface in Greenland, it gets warmer,” adding, “The surface is very cold, but it can be as much as 20 degrees warmer just 30 to 40 feet up in the air. It’s enough that you can feel the difference between your nose and your toes.”
In most places, the higher up from sea level you go, the colder it gets. Greenland is a little different in that the higher you go, the warmer it gets. “The temperature difference effectively forms a lid so that there is hardly any evaporation. Warm air likes to rise, but if it is already warmer up above the air is trapped nearer the ground,” Noone says. As water evaporates from the ice sheet’s surface, layers of fog form after the water evaporates. These “fog water-drops drift back down to the very cold surface where it refreezes onto the ice sheet.”
Noone says this is a “handy little trick of nature.” The study’s lead author, Max Berkelhammer, a researcher at the University of Illinois, indicates that scientists have known about these “accumulation zones” on high-altitude areas of Greenland’s ice sheet. But because it is difficult to do an in-depth analysis of evaporation and condensation over extended periods of time, this is the first time a research group has been able to monitor this phenomenon for an entire year.
“Instruments capable of doing this are pretty new and while they have been used before on the ice sheet, they have never been able to run during an entire winter,” said Berkelhammer, “I think at this point we are still the only group who has been able to run this type of instrument for an entire year on top of an ice sheet.” Part of their goal was to measure how well ice cores encapsulate past temperatures in Greenland.
Most of the snow and ice on the island’s interior came from evaporated sea water in the south and ferried northward by wind and storms, falling as snow on the ice sheet. Successive snowfalls gradually compact the snow into ice, building it up over time, just like in Antarctica. By measuring the “ratio of oxygen and hydrogen isotopes in the water,” researchers can track its origins and ultimate fate.
