Located across the middle of the vast Greenland ice sheet are a network of 16 climate stations, which track winds, snowfall accumulations, melting of snow and ice, sunlight and temperatures.
This array has been in place since 1995, funded in part by NASA and the National Science Foundation, and painstakingly installed and maintained via expeditions to the ice by pioneering climate scientist Konrad Steffen and his crew of graduate students and other researchers.
Steffen died earlier this year when he fell into a crevasse while working on the ice.
The United States has decided to end its financial support for the monitoring network, but the Geological Survey of Denmark and Greenland is stepping up to the plate to continue operating these stations. Their importance to climate scientists will only grow as they provide researchers with a long-term perspective of how climate change is playing out on the ice sheet itself.
According to Jason Box, research leader for the Greenland Climate Network, also known as GC-Net, and a research professor at the Geological Survey, the continued operation of these stations is crucial for giving scientists like him ground truth of what satellites and other remote sensing instruments are showing about how quickly the Greenland ice sheet is melting.
Map of GC-Net (blue) and PROMICE (red) stations in Greenland. (Jason Box)
By 2025, it will have been 30 years since these instruments began monitoring conditions on the ice, and this is the period of time generally considered necessary for establishing so-called average climate conditions.
“By supporting a series of short-term science studies, the U.S. enabled my (recently late) mentor Konrad Steffen to sustain the GC-Net for more than two decades. Now Denmark is carrying the torch forward as we are approaching 30 years of observations — the period of time key to separating the year-to-year ‘noise’ from the climate trend,” Box said in a statement.
When combined with other monitoring stations in Greenland, such as the Program for Monitoring of the Greenland Ice Sheet (PROMICE), which operates a slew of climate stations on the edge of the ice sheet, the instruments help measure Greenland’s loss of ice, or mass balance.
“We do have some advanced satellite and model capabilities, but you never know what you have until you do this ground truth work,” Box said in an interview. Box was involved in constructing and maintaining GC-net from its early days in the mid-1990s through at least 2006, and was with Steffen when he died Aug. 8.
“I was the only graduate student, I was 20 when I started, in 1994. I didn’t know it at the time but it turned into an attractive opportunity to continue the fieldwork on Greenland,” Box said. “It’s amazing how much we have learned since the early 1990s,” he said, noting that in the mid-1990s it was not known whether much of Greenland would warm and lose ice mass during this century, raising global sea levels.
Now, though, the warming and melting trends are obvious and alarming.
Studies have shown the ice sheet has lost 4 trillion tons of mass since 1992, and is now the largest contributor to global sea level rise.
“Go back to when this first got started back in the early 90s; back to when we were starting to get some indications that the planet was warming but we didn’t know what it meant,” NASA climate scientist Tom Wagner said of GC-Net’s early days in an email. “Go forward a decade to about 2000, and now we know sea levels are rising more than just from ocean warming, and it appears that Greenland is losing mass, but it’s hard to tell how much,” Wagner said.
“But by 2000 we start having enough data from this network and related fieldwork to say, ‘Whoa! Greenland is getting warmer! A lot warmer! And it’s losing mass!’" he said.
Wagner said the network serves as a critical check to determine the accuracy of satellites measuring changes in the Greenland Ice Sheet, such as through surface melting and the transport of glaciers into the sea.
“We’ve got what amounts to a Keeling curve for Greenland surface temperatures and other observations,” Wagner said, referring to the iconic chart showing increasing amounts of carbon dioxide building up in the atmosphere. That data was recorded atop Mauna Loa Observatory in Hawaii.
Like the Keeling Curve, said Waleed Abdalati, who directs the Cooperative Institute for Research in Environmental Sciences in Boulder, Colo., and helped fund GC-Net while at NASA, GC-Net “Was started out of a drive to understand what was happening. Now we have a treasured data set that has told us more about climate than we could have imagined at the time. As Greenland’s story is unfolding, we continue to learn more from those anchor records,” he said via email.
Box said his former mentor was extraordinarily skillful at securing funding to build up the network, but that the United States never intended to fund the stations long-term, so the shift in support is a positive development.
“One should only be proud of the support the U.S. gave to this network through all of these short-term contracts that Konnie was able to secure,” Box said, describing how U.S. science agencies “went along with a far-flung network of sticks out on the ice sheet.”
The data from GC-Net flows to the public free of charge and will be incorporated into weather models to improve the accuracy of predictions, he said.
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