You’ll forgive Jason Box for being a little impatient these days. After all, you would be too if you were in his position. As a geologist specializing in Greenland's glaciers and climate at Ohio State’s Byrd Polar Research Center, in the summer of 2009 Box placed high resolution, wide-angle time-lapse cameras along the Petermann Glacier in northwestern Greenland, near where it flows into the sea.
Then, this past summer, a 290 square kilometer chunk of ice (that’s about four times the size of Manhattan) broke off the ice shelf and floated away. Those cameras, as far as he knows, captured the extraordinary event in vivid detail.
There’s just one problem — he hasn’t been able to go back to retrieve the images.
So far the world has only seen NASA satellite images of the ice shelf breakup, which, interesting as they may be, are difficult to put into context. On-the-ground imagery of such an ice loss event could help drive home the reality of how quickly climate change is reshaping the Arctic, and what it means for the rest of the world given the ice’s role in raising global sea levels.
Unfortunately for Box, who served as the lead author of the National Oceanic and Atmospheric Administration’s (NOAA) “2010 Arctic Report Card,” he was unable to obtain the funding and logistical support last year — such as a ship and a helicopter — needed to retrieve the hourly images, and add more equipment in an effort to document the glacier’s movement.
“It’s likely [the cameras] operated,” Box says, “and if they did, some very wide angle, high res. photos” were obtained, pointed right at the area where the ice broke free from the glacier.
“It was pretty difficult to turn our backs on it this year,” he says, noting that, thanks to new support from the National Science Foundation and a donor in the U.K., he plans to return to Petermann with his colleagues by the spring of 2011.
“We just need to put the logistics into place.”
Growing Concern About Fate of Marine-Terminating Glaciers
The Petermann Glacier isn’t just a photogenic location, it’s also a central focus of research as scientists try to ascertain how quickly and extensively Greenland’s ice cover is melting due at least in part to global climate change. Their focus is increasingly turning to Greenland’s northern glaciers, which are showing the greatest mass loss and are dominating the losses of ice area, Box says.
Scientists are using satellites such as NASA’s Gravity Recovery and Climate (GRACE) satellite and field studies to keep tabs on glacial ice. They are observing differences in melting trends between so-called “ice shelf glaciers,” which have a floating area of ice known as an “ice tongue” that is present year-round, and glaciers that develop seasonal ice tongues.
Box says ice shelf glaciers, such as Petermann, are showing a greater sensitivity to the warming climate, but that large amounts of ice were lost throughout Greenland during the 2010 melt season.
“There is a signal of ice shelf loss within these warm years that suggests that the ice shelf loss at Petermann and some of these other large glaciers is with some confidence triggered by these warm summers,” he says.
As is explained in the Arctic Report Card, which was released last month, scientists are especially concerned about marine-terminating glaciers such as Petermann, because they serve as the outlets for large amounts of ice from the land into the sea.
Box says a large calving event, such as what occurred with the Petermann Glacier, can speed up a glacier’s slide towards the sea:
It is of concern because there is no expected or known mechanism to reverse the accelerated loss. It’s like removing a cork from a bottle. It will take an extended cold period to grow back the glacier ice on the front of a glacier like Petermann.
“The big question I think everyone wants to know,” Box says, is whether global warming is driving the ice loss such as the calving event seen last summer.
“[The] Balance of evidence is strongly suggesting” a relationship to warming temperatures, Box says, but exactly how such warming is driving ice loss is unclear. He notes two warming-related processes that are probably playing a role: surface melt and “hydrofracture,” a process by which water fills crevices in the ice and forces them apart.
Warmest Summer in Greenland Since Records Began in 1873
According to the report card, last summer was Greenland’s warmest since instrumental records began. Collectively, marine-terminating glaciers lost an area of 419 square kilometers, which is 3.4 times the loss rate seen during each of the previous eight years.
“There is now clear evidence that the ice area loss rate of the past decade is greater than loss rates pre-2000,” the report card states. The report also notes an expansion of the area and duration of Greenland ice melt during 2010, compared to past years.
As Box puts it, “What happened in Greenland really was exceptional in the observational record.”
Image: Ohio State University/Jason Box
Republished by permission