Should the entire ice field melt, scientists know the world's oceans would rise about 23 feet and decimate many coastal areas, including the bulk of the United States' eastern seaboard.
Even if the cap partially melted, scientists predict the runoff would sink a significant number of coastal areas.
“From satellites, we have fairly good records of what sea levels are doing and how it is coming up,” Harper said. “We know it is coming up 3-plus millimeters a year, but the question is where is it coming from?”
To that end, Harper has set out to answer one burning question: What happens to the Greenland ice cap's meltwater?
Does it escape the ice sheet and become a cause of sea level rise around the globe? If it does escape the frozen confines of the cap, how much of the meltwater escapes? Does it refreeze? If it doesn't freeze, can it disperse by traveling along ice layers?
With a $524,000 National Science Foundation grant, Harper set out for the lonely landscape this summer to find out. Joining him on the provocative research project were colleagues from the University of Colorado and University of Wyoming, plus three graduate students.
Their goal: to take ground samples at the Greenland ice cap's highest and lowest elevations, and to determine at what elevation meltwater is escaping into the oceans.
It will take the team two summers to gather all the data they'll need to know the fate of the meltwater, Harper said. But now that he's back in his UM office and has begun studying the information his team gathered from their first foray, he's finding some encouraging - if initial - answers.
“So far, we are finding that high up on the ice sheet, the meltwater is refreezing and not escaping,” Harper said. “Although this is our preliminary findings, and we have only done half the problem because we haven't yet studied the lower elevations - this is important news.”
Each winter a huge amount of water falls on the ice sheet in the form of snow, but each summer snowmelt and icebergs release water back to the sea.
“The fluxes of water in and out are so huge that only a slight imbalance between the gains and losses would lead to a substantial sea level rise,” Harper said.
All together, scientists believe the ice cap is now responsible for raising sea levels by a half millimeter per year, Harper said.
“We are talking huge fluxes of water going in and out of the ice sheet,” he said, “and the smallest imbalance can lead to large changes in sea levels each year. The work we are doing is trying to figure out what the imbalance is. By knowing how much of that water is escaping, it will tell us Greenland's role in current sea level rise and the potential it would have on the future.”
While many people assume the current rise in sea levels is due to the melting of Greenland's ice cap, the source is more likely melting at the world's smaller glaciers, like the ones in Glacier National Park, Harper said.
“Those smaller glaciers are the major contributor to the sea level rise now,” he said. “Those small glaciers contribute about 1.1 millimeters per year, and the Greenland ice cap contributes about 0.5 millimeter per year - at least that's our best estimate right now.”
For four weeks during June and July, Harper and his research team lived in tents on the ice cap and navigated their lives with Global Positioning Systems. Without the technology, the research would have failed and the team would not have returned from the world of ice, Harper said.
“The ice cap is a featureless landscape, and after a while you stop wondering if you should look up because there is nothing to look at,” he said. “You need a GPS to figure out where you are going at all times because you can't really tell which way is up or which way is down.”
The sun doesn't set at the top of the world, and there's no real difference between day and night. There is no wildlife to watch, no flora or fauna to mark the horizon and break the monotonous view.
Sometimes, on a rare clear day, the sky is bright blue, and on those days, Harper said, you can see the difference between land and sky.
Otherwise, he said, “It is just an endless flatness - and snow. When the snow gets blowing you can't really tell what's up or down.”
To conduct their research, the scientists trekked 60 to 70 miles a day using snowmobiles and skis. The group installed two meteorological stations, used radar to map ice layers beneath the snow, drilled 21 35-foot-long ice cores, dug snow pits and did numerous experiments with colored dye to track meltwater flow.
The scientists also installed a series of temperature sensors to record melting and freezing events in the cap up to 35 feet deep.
Next summer, the crew will return to study another 75-mile stretch at the cap's lowest elevations.
In the warm, lower climes, Harper expects to find water on the run.
“I suspect things might really be moving down below, but so far in the upper part of the ice sheet, we have thrown that out,” he said. “In that area, we found the melt is increasing every year, but it isn't going anywhere.”
|
 |
 |
Add your comment now! Write your comment in the form below.
(Email address is for verification only. If you'd like to email a story, look for the link above)