‘Oh my God, what is that?’: How the maelstrom under Greenland’s glaciers could slow future sea level rise
Out Icefjord A Ilulissat, Sean Picture: Visitor Gallup/getty Ilulissat Crowding Near Greenland At The Looks Melting Icebergs Western
There are stadium-sized blocks of ice crashing from the soaring face of the Kangerlussuup glacier in western Greenland. Fierce underwater currents of meltwater are shooting out from its base, and visibility below the surface is virtually zero thanks to a torrent of suspended mud and sand. It’s little wonder scientists have never explored this maelstrom.
Yet today, they are sending in a multimillion-dollar remotely operated submarine — potentially to its death. As the scientists onboard the Celtic Explorer research ship repeatedly say: “It’s a high risk, high reward mission.”
The reward is solving a mystery that could transform the understanding of the most profound long-term impact of the climate crisis: Surging sea levels.
Glaciers fed by ice caps are increasingly disintegrating, and how fast this will accelerate directly affects a billion people in the world’s great coastal cities.
However, current models do not take account of a big possible factor: The huge mounds of ground rock that some glaciers pile up in front of them, blocking their paths and insulating them from ever hotter oceans.
However, the role this plays is unknown because researchers had never been able to scrutinise the hellish zone where mighty glaciers, rock, and ocean meet. Now, they are.
“Oh my God, what is that?” says Prof Ginny Catania, the expedition’s chief scientist, from the University of Texas (UT). She is looking at the screens in the tense control room on the ship. The live sonar feed from the submersible has revealed a vast underwater cavern in the glacier.
The engineer, Victor Naklicki, is piloting the sub, a feat of fierce concentration over the 10-hour dive.
Afterwards, he says: “It was pretty crazy down there — we saw the big cave and you could feel the [sub’s] thrusters working very hard to not get sucked right in.
"We made it 50minto it, but it went even deeper — it was an abyss.”
The move inside went against all conventional piloting wisdom, he says, as putting a remotely operated sub under anything means it can’t float back to the surface if something goes wrong.
The biggest of the prizes is taking core samples of the sediments piling up right at the glacier’s foot — nobody has got closer than 500m before. But delicately manipulating the robot arm in zero visibility, while piloting the vehicle, is extraordinarily difficult.
“It’s like you’re driving through a blizzard up in Buffalo, New York, while doing origami over in the back seat, as the car is moving around at 60 miles an hour,” Mr Naklicki says.
The submersible, called Nereid Under Ice (NUI), has other close scrapes. A deluge of mud and sand dumped 25kg on the vehicle at one point, threatening to ground it.
During another dive, an iceberg the size of 45 football pitches crashed off the glacier — without an unplanned launch delay, the submersible could have been crushed. “We dodged a bullet,” says Rosemary Loer, another of the submersible team, from Woods Hole Oceanographic Institution (WHOI).
“But there’s no better feedback than when the scientists are standing behind you and they’re like: ‘Oh my God. This is crazy. We never expected this. This changes everything’,” Mr Naklicki adds.
The data from the submersible is critical to solving the mystery of how sediment banks may slow glacier break-up.
“Model projections for the future of Greenland are just all over the place,” says Ms Catania.
“Very rapid sea level rise has been documented in the past and so: Is it possible to get that again? We are certainly perturbing the climate system enough.”
Amid warnings of potential collapse of the Greenland ice sheet, which would push up sea levels by 7m, a better understanding of when the map of the world may be redrawn is vital.
Prof John Jaeger, from the University of Florida, leads the sediment experts onboard the expedition ship.
He says: “In Florida, we clearly see sea level rise already: Coastal cities there are already getting flooded out on high tides.
"If we begin to melt a lot of ice, and [a glacier] begins to move very quickly, it can actually create a lot of sediment, and maybe that is a feedback mechanism that will slow it down," he adds.
Fully understanding this process requires a swathe of scientific expertise, and the ship is a floating laboratory — with a spectacular view.
Some 2,000m mountains tower over the remote fjord, with tributary glaciers snaking their way down to the ice strewn water, all glittering in the 24-hour sunlight. Thunderous rumbles roll through the cold air as giant icebergs calve, while fizzes and pops come from the melting ice as ancient bubbles of air are liberated.
The focus is the colossal glacier at the end of the 50km-long fjord. Its ragged face is 5km wide and 300m tall, much of it hidden below the surface.
While beyond the ship there is a savage serenity to the fjord, onboard there is a buzz of activity day and night, with every moment in this remote place too valuable to waste.
The submersible is the focus of the day shift, led by Molly Curran from WHOI, and is lowered into the water with the care of placing a baby in a cot. Then, it ventures off into the violent world of the glacier’s terminus — connected only by a hair-thin fibre-optic cable, kilometres long, which allows it to roam to places other remotely operated vehicles cannot.
Ms Curran’s colleague Mike Jakuba says wryly: “If we lose the vehicle, that would be a lot of paperwork. But the pressure is not about the vehicle — it’s about delivering for the scientists.”
The submersible is packed with kit doing just that: Scanning the glacier face and sediment banks in high resolution, measuring the velocity, temperature, and saltiness of the water, and grabbing those crucial samples.
Mr Jaeger, celebrating the 30th anniversary of his first Arctic expedition, says: “I could never get closer [to the glacier’s terminus] than about a kilometre because of safety reasons. That gap was always frustrating. Now [the submersible] gives us the chance to get in there and collect these amazing datasets.”
On the day shift, drones repeatedly map the ever-changing shape of the glacier from the air — it moves 5m a day — building up an extraordinary 3D picture of its face.
One major goal for the drone is to spot where cloudy, sediment-laden plumes are gushing out of the glacier. “Sometimes it looks like a boiling pot,” says UT engineering scientist Marcy Davis.
At night, the glacier and fjord are probed in different ways.
Multiple seismic surveys, including the “chirping” that regularly echoes around the ship, sees through the seafloor to the layers beneath. These will reveal how the sediment banks have been built in the past, and the best places to sample long cores.
This requires dropping a 6m weighted tube straight down into the seabed like a torpedo.
“That’s probably about 20 years of sediment,” Mr Jaeger says, examining faint annual layers in a 2m-long sample.
Oceanographer Bridget Ovall, from Rutgers University, says the team are inventing new strategies on the fly to measure the speed of the underwater currents.
“We’re having to make it up as we go along, as no one has done this before," she explains.
As the first measurements came in, Ms Catania says: “I cried a little bit, because it was really exciting to see and finally the drudgery of planning this for years was paying off.”
The expedition had been a decade in the making, drumming up funding for such a high-risk project, then getting the scientists and all their kit into the Arctic Circle, and then finding the right fjords not blocked by minefields of ice.
The incredibly high-resolution data gathered by the submersible is unique, she says, adding: “It was like putting glasses on for the first time, when you can suddenly see all the leaves in the trees. The detail is striking, like seabed channels that we’ve never seen before — that we didn’t know even existed.”
“Now the fun starts, to try to interpret it all, understanding what the heck it is that we’re even looking at,” Ms Catania says. “The observations are so novel that even the ways that we process the data have to be changed.”
That will take time, but the implications of the work in this inhospitable corner of Greenland could reverberate across every country with a coastline.
“I’m hoping it will make a big impact in terms of understanding,” she says.
“We know that, in these systems, there are tipping points,” the expeditions’ co-chief scientist, Prof Sean Gulick, says.
“But if a glacier creates a large pile of sediment, it might delay some of the catastrophic retreat that people are most worried about.
"These glaciers in West Greenland are particularly important because they’re fed directly from the Greenland ice sheet.
“They are the frontline of the battle between the [warming] ocean and the ice,” he says.
Other recent research has shown Greenland’s ice sheet vanished in the past when global temperatures were similar to those today.
Not all glaciers build giant sediment banks, but knowing whether this affects the biggest and most dangerous glaciers in Greenland and Antarctica will be critical information, says Ms Catania.
That is because sea level rise does not happen evenly around the world.
“So, if we can say where this sedimentation process is more important, that might help us to understand what cities are going to be more at risk from the collapse of ice sheets,” she says.
“On the Texas coast, a lot of people live in houses on stilts because of hurricanes,” she says.
“If you’re building, you want to know, do you need to build it 4m high or 8m high?” The research could even inform a geoengineering idea. “One proposal has been to try to shore up our glaciers and ice sheets against the impact of warming ocean water, by building barriers,” UT ice modeller Benjamin Keisling adds.
“Of course, that represents a massive undertaking — logistically and financially — but the ocean is taking up more and more heat as the atmosphere warms,” he says, "building a barrier like that seems absurd, but then you realise that’s actually something that nature does naturally.”
The sediment banks may prove to be a helpful delayer of sea level rise in places, giving communities a little more time to prepare, but substantial rises are already unavoidable, warns Ms Catania.
"We don’t know when, and certainly we need to answer that question, but we have little planning at many coastlines — especially in the many countries that are not wealthy, that are going to get completely inundated.”
The scientists onboard the Celtic Explorer are dedicated to answering these crucial climate questions, and aware of the stakes for humanity, but there is also space aboard for personal reflection as the expedition ends successfully, with a host of brand new data.
The submersible’s pilot, Mr Naklicki, uses a modified Xbox gaming controller to fly the submersible.
“Growing up, I played a lot more video games than my parents would have liked. But there’s some good pictures of me on this cruise using that controller. I wish I could take that picture back in time and show my parents when they told me to stop playing games and do my homework. It paid off eventually.”
Ms Catania is also thinking of family: “This is the longest I’ve been away from my kids. My husband passed when I was supposed to come here in 2013 and so I didn’t come — my kids were two at the time. So me being able to come here is a big coup.
"The logistics for this cruise was one thing, but I also had to plan the logistics for leaving my children with family and friends and stuff for the last month as well. It’s really going to be nice to be home.”
The Marine Institute’s RV Celtic Explorer left Galway on July 21 and, following a port call in Nuuk, the capital of Greenland, it travelled to Uummannaq in early August.
The voyage took the RV Celtic Explorer to remote locations beyond its typical expeditions in Irish waters, for scientists to observe how glaciers are changing using innovative technology.
The research, led by Prof Ginny Catania, is a collaborative project between the University of Texas, University of Oregon, and the University of Florida.
Results from the study will determine the degree to which moraines can be built fast enough to offset the retreat of glaciers from climate action. An unmanned surface vessel, provided by Irish company XOcean, helped researchers in obtaining data from previously inaccessible locations.
- Guardian
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