News | February 15, 2017
Glaciers on the edge
“This year we’re gonna bring it!” Oceans Melting Greenland (OMG) Principal Investigator Josh Willis told me excitedly. “It’s the beginning of year two of this five-year airborne mission, which means that by comparing data from the first and second years, we’ll be able to observe changes in Greenland’s glaciers and coastal ocean water for the first time.” Glaciers around Greenland’s jagged coastline have been melting into the ocean and causing increased sea level rise, so measuring the amount of ice mass loss will help us understand the impact of these changes, Willis said. “Will we see 5 feet of sea level rise this century … or more?”
See, Earth’s ocean, more than the atmosphere, is responsible for creating a stable climate. And as global warming has increased the temperature of the ocean waters surrounding Greenland, that warmer ocean water is melting the ice sheet from around its edges. “Hey! The ocean is eating away at the ice sheet!” Willis often cries when explaining the mission. And Team OMG is measuring how much of that warm water could be increasing due to climate change.
Decoding the environment
I understand how Willis and Project Manager Steve Dinardo get excited about measuring sea level rise. Greenland’s ice melt is accelerating, which explains why NASA is paying attention to it. Plus, after a successful first year, the team is fully aware of the stark beauty of Greenland’s rugged landscape and seascape and the rewards of bonding as a team. Dinardo told me he was “ecstatic about the incredible progress Team OMG has made in the last twenty-two months.”
After a successful first year, the team is fully aware of the stark beauty of Greenland’s rugged landscape and seascape and the rewards of bonding as a team.
As scientists, decoding the natural world is our way of caring about the environment. We care about Greenland’s icy coastline, so we go there. We go there and observe. We go there and measure. For there is something undeniable about the sheer beauty of this planet, and any time you get to experience it is a moment to feel exuberant and alive. Plus, flying around with a great team in a modified NASA G-III aircraft ain’t too shabby either.
But wait. Before I continue, there’s something you probably noticed: Willis said he named this Greenland observing expedition Oceans Melting Greenland, or OMG for short, because, hey, OMG is the exact response you might have when you find out what’s going on up there.
Parts of Greenland’s coastline are so remote, so difficult to access by boat, that they’d remain uncharted, especially under areas that are seasonally covered with ice. Imagine the edge of an unimaginably complicated winding coastline, that unknown place where ice meets water meets seafloor. Big chunks of remnant sea ice clog up the water, and the glacier has retreated so recently that the coastline is changing as fast as, or even faster than, we can study it.
The seawater around 400 meters deep is 3 to 4 degrees Celsius warmer than the water floating near the sea surface. And the sea floor bathymetry influences how much of that warm subsurface layer can reach far up into the fjords and melt the glaciers. So, to learn about the interface between where the bottom of the ice sheet reaches out over the seawater and down into the ocean, OMG began by mapping undersea canyons on the M/V Cape Race, a ship equipped with an echo sounder, which sailed right up the narrow fjords on the continental shelf surrounding Greenland to the places where the warmer Atlantic Ocean water meets the bottoms of the frozen, 0-degree glaciers. The crew had to snake in between floating icebergs and weave in and out of narrow fjords. The Cape Race used a multibeam echo sounder to map undersea canyons, where the warm seawater comes in contact with and melts the glaciers.
The next four years
In the spring of 2016, the Oceans Melting Greenland (OMG) team began surveying glacier elevation near the end of marine-terminating glaciers by precisely measuring the edges of the ice sheet on a glacier-by-glacier basis, using the Airborne Glacier and Land Ice Surface Topography Interferometer (GLISTIN-A), a radar instrument attached to the bottom of a modified NASA G-III aircraft. Data collected this spring and over the next four years can be compared with data collected in the spring of 2016 so we can determine how fast the glaciers are melting.
As scientists, decoding the natural world is our way of caring about the environment.
The investigation continued into last fall, with the team dropping more than 200 Aircraft eXpendable Conductivity Temperature Depth (AXCTD) probes that measured ocean temperature and salinity around Greenland, from the sea surface to the sea floor, through a hole in the bottom of the plane. “In most of these places,” Willis told me, “there’s been no temperature and salinity data collected. Ever.”
The team will drop more ocean probes across the same locations to find out “how much ice melts when the water is this warm,” what the melt rate is, and how much that rate is increasing, because no one knows the melt rate yet.
Big picture project
“OMG is a big picture project,” Willis explained. ”We want to see what’s happening in the ocean on the large scale and what’s happening to the ice sheet on the largest scales.”
As part of Team OMG, I also flew on NASA’s G-III into uncontrolled airspace to places where no other aircraft had flown before, into narrow and steep ice-covered fjords, winding in and out, up and down, over and through to observe and measure, like scientists do. I saw the brilliant white ice carve its way through steep brown valleys into open ocean water. I saw the glorious expanse of white upon deep blue going on and on and on below us as we flew just 5,000 feet above the winding coastline. It was extraordinary.
And if you just thought “OMG,” Willis would be proud.