Above: “Tent City” houses scientists visiting the National Science Foundation’s research station on the summit of the Greenland ice sheet. Photo by Lauren Morello.
How can robots help scientists canvas unchartered territory in the world's coldest, most desolate regions? ClimateWire's Lauren Morello explores a National Science Foundation-funded project to perfect Yeti Robot and Cool Robot to collect data on the Greenland ice sheet. Click here to read the special report.
Climate change has accelerated the melting of Greenland's vast ice sheet. ClimateWire traveled there to follow researchers studying the changing polar environment.
Third in a three-part series.
KANGERLUSSUAQ, Greenland -- In her knitted ski hat, parka and hiking boots, Åsa Rennermalm doesn't look like an accountant -- or a plumber.
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| Rutgers University hydroclimatologist Åsa Rennermalm is trying to answer a deceptively simple question: When Greenland's ice melts, where does the water go? Photo by Lauren Morello. |
But the Rutgers University hydrologist draws on both disciplines as she works at the southwestern edge of Greenland's vast ice sheet. She's spent the past four years trying to answer a deceptively simple question: When Greenland's ice melts, where does the water go?
"Satellites show the surface of the ice is melting and the volume of ice is decreasing," Rennermalm says. "But how much meltwater is leaving and reaching the ocean? That will influence future sea level rise."
She and colleagues from the University of California, Los Angeles, are studying the runoff from one chunk of the Greenland ice sheet -- Russell Glacier, which sits 16 miles outside of this small town.
Because it rests entirely on land, it isn't vulnerable to the influxes of warming ocean water that cause outlet glaciers to calve. The main way Russell loses ice is surface melting. Some of the resulting water runs off the glacier into nearby lakes and streams. Some drains into cracks and channels in the ice, where it can refreeze or flow to subglacial streams and lakes that feed into the sea.
The scientists are trying to track the water that runs off Russell Glacier and trace it back to its source.
"We want to understand what happens to meltwater," Rennermalm says, showing visitors around her team's camp on a sunny July day. "What we're doing here is providing a piece of the puzzle, because we're looking at the margins of the ice sheet."
A few days into the group's two-week field season, it's clear there are still kinks to be worked out.
Rennermalm and her assistant, Colin Gleason, are crouched at the edge of the glacial stream that runs next to their camp. They've run into trouble with the equipment they use to measure the water's speed and depth, and it's time to double-check the wiring.
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| University of California, Los Angeles, researchers Larry Smith and Vena Chu get ready to measure the speed and depth of a stream fed by meltwater from nearby Russell Glacier. Photo by Lauren Morello. |
But a few miles up the rocky dirt road, the UCLA group is having more success. They're dipping another set of the same instruments -- this time attached to a long silver pole -- into the silty water rushing under a small plank bridge.
A few miles away, in Kangerlussuaq proper, temperatures are mild, in the low 70s. But here, closer to the glacier, a strong chill wind blows as geologist Larry Smith and doctoral student Vena Chu go about their work.
Just after 4 p.m., the current is strong and the water is rising. That's not unusual. The temperature on Russell Glacier peaks at around 1 p.m. each day, and the water level responds a few hours later, hitting its daily high.
"This morning, the stream was 2 feet lower," Chu says. "But last night around 6 or 7 p.m., it was hitting the bottom of the bridge."
Smith lowers the instrument pole into the water. The bottom of the pole rests on the streambed, and markings along its length reveal the water's depth. A silver pinwheel that sits a few inches from the bottom of the pole will reveal the stream's speed.
Every five spins of the pinwheel, an attached "squawk box" beeps. The scientists can convert the number of beeps over a certain period of time to the speed of the current in meters per second. Chu's job today is to monitor the output from the squawk box.
The researchers will take that information about the water's speed and depth and combine it with measurements of stream width to estimate how much glacial meltwater reaches the three different locations the team monitors.
"All the water here is coming from the ice sheet," Rennermalm says, but each site gives different information about the ice sheet's inner workings.
The place Smith and Chu are working today is fed by a stream that flows underneath Russell Glacier. The area where Rennermalm and Gleason are stationed is fed by overflow from an ice-dammed lake that collects meltwater from the glacier's surface. A third site receives water from both sources.
But the data they're collecting are limited. The researchers want to know how glacial runoff changes from season to season and year to year, but they're only able to visit Greenland for a few weeks each summer. To solve that problem, they've installed pressure gauges at the three stream sites that record the water's height every 15 minutes, year-round.
By comparing their summer field measurements with pressure gauge data from the same periods, the scientists know which stream heights correspond to different water speeds. That allows them to estimate glacial discharge at each of the sites throughout the year. It's a good system, but not a perfect one.
"We have some data that suggest melt events are occurring in the winter," Rennermalm says. "But we're very uncertain about those data. Our instrument measures something, but what does it mean?"
Her team is confident, however, that they understand what's happening during the summer melt season. They hope to use that knowledge, and the data they're collecting, to model how water drains from the glacier -- and how much of that water reaches the ocean, where it can raise sea level.
Rennermalm is also working with researchers at the University of Alaska, Anchorage, to track the chemical composition of glacial runoff.
"What we hope to do is fingerprint where the water is coming from," she said, "whether it's from the surface of the Greenland ice sheet or subglacial lakes. We want to understand, how did the water get in the stream?"
SUMMIT STATION, Greenland -- At first glance, this research station on the highest point of Greenland's vast ice sheet doesn't look like much.
A scattering of trailers perch on stilts high above the snow, with a neat grid of small yellow tents off to one side. There's a tall metal tower, a few outhouses. A pile of black fuel bladders stands in stark contrast next to the carefully groomed ice runway.
But this nondescript outpost is a magnet for scientists trying to answer some very big questions. Do clouds and tiny aerosol particles help warm or cool Greenland's ice and the air above it? How fast is the climate here changing? How quickly is Greenland's ice sheet melting?
Researchers established the first camp here in 1989, at the start of an international effort that drilled the 3,053-meter-long Greenland Ice Sheet Project-2 ice core, retrieving a record of climate over the previous 110,000 years.
That project ended in 1993. It wasn't until nearly a decade later, in 2000, that the National Science Foundation turned the camp perched on the apex of Greenland's ice, 2 miles above bedrock, into a year-round research hub. The station, manned by a six-person crew in winter, hosts up to 50 people at a time during the bustling summer research season.
This year, Summit's list of long-term visitors includes Brandon Strellis, an environmental engineering graduate student from the Georgia Institute of Technology studying how aerosols influence how much energy is reflected and absorbed by Greenland's ice -- and where those particles are coming from.
One aerosol, black carbon, is of increasing concern for Arctic nations worried about the pace of climate change in the far north, which is warming twice as fast as the global average. Sooty particles of black carbon, produced by burning fossil fuels, wood and dung, warm the atmosphere by absorbing heat from the sun. And when they land on Greenland's snow and ice, their ability to absorb heat from sunlight increases surface melting.
SUMMIT STATION, Greenland -- The midnight sun is shining on the Greenland ice sheet, and Yeti Robot is out for a spin.
The probe's chunky tires crunch a trail through the snow, then jerk to a stop. A blue plastic sled carrying a ground-penetrating radar crashes into Yeti's boxy black chassis, still tied to the robot by nylon ropes.
Yeti's handlers try to diagnose the problem. The robot is swinging too wide on its right turns, straying from the path programmed into its onboard GPS. The engineers confer. Seconds later, Yeti is again whizzing toward the horizon.
It's the first day of this year's field tests, and the researchers are eager to show off their prize pupil. If all goes well, battery-powered Yeti and its close relative -- a solar-powered version called Cool Robot -- could one day expand scientists' access to Earth's poles and enhance their ability to study how climate change is speeding the melt of Greenland's ice sheet.
The robots are part of a new breed of autonomous rovers, submarines, ocean gliders and unmanned aircraft designed to go places scientists can't, to handle jobs that are too dangerous or too costly for researchers to undertake themselves.
"It's expensive to put researchers in the field," said Jim Lever, a mechanical engineer at the Army's Cold Regions Research and Engineering Laboratory who helped develop Yeti and Cool Robot with colleagues at Dartmouth University and the University of New Hampshire. "You have a logistics train to support them."
That logistics train includes the U.S. Air Force's ski-equipped LC-130 cargo planes, which ferry personnel, scientific equipment, food and other basic supplies to the National Science Foundation's research camps in Greenland and Antarctica. The flight that brought Yeti's handlers to the summit of Greenland's ice sheet in mid-July carried everything from a fresh supply of weather balloons to a crate of cantaloupes.
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