Science & Technology

NASA Continues to Research Greenland Ice Sheet Melt and Sea Level Rise

Streams and rivers that kind on high of the Greenland ice sheet throughout spring and summer time are the principle agent transporting soften runoff from the ice sheet to the ocean. Credit: NASA’s Goddard House Flight Middle/Maria-José Viñas

Scientists collect area information on the Greenland Ice Sheet to assist confirm local weather fashions which can be used to estimate future sea stage rise and to incorporate the measurements into pc fashions that may create a simulation of the soften water runoff processes working on the ice sheet.

On Greenland’s ice sheet, an enormous icy panorama crisscrossed by turquoise rivers and dotted with soften water lakes, a small cluster of orange tenting tents popped up in late July. The camp, residence for per week to a group of researchers, sat by a big, fast-flowing river. Only a kilometer downstream, the river dropped right into a seemingly bottomless moulin, or sinkhole within the ice. The low rumble of the waters, the shouted directions from scientists taking measurements, and the chop of the blades of a helicopter delivering personnel and gear was all that was heard within the frozen panorama.

This camp was Laurence C. Smith’s area analysis website in west Greenland. Smith, a professor and chair of geography at College of California, Los Angeles, and his NASA-funded group had been finding out the hydrology of the ice sheet – how the shifting community of streams and rivers that kind through the soften season transport water from floor of the ice to the ocean, contributing to sea stage rise.

“Floor melting in Greenland has elevated lately, and we lacked a rigorous estimate of the water volumes being produced and their transport,” mentioned Tom Wagner, the cryosphere program scientist at NASA Headquarters in Washington. “NASA funds fieldwork like Smith’s as a result of it helps us to interpret satellite tv for pc information, and to extrapolate measurements from the native area websites to the bigger ice sheet.”

Mysterious Drainage Networks

Greenland loses ice to the ocean primarily by means of two processes: the shedding of icebergs from glaciers that run into the ocean, and floor soften runoff.

“Strong ice losses have been studied in nice element by scientists for years, however the soften water part, regardless of being the dominant agent within the ice sheet’s mass stability, has obtained comparatively much less examine,” Smith mentioned. “That is notably true for the floor water hydrology on high of the ice sheet, which has obtained little or no examine.”

The handful of ice sheet floor hydrology research have principally targeted on Greenland’s large soften water lakes, which might disappear in a matter of hours, engulfed by the ice. However Smith and his group consider that rivers sinking into holes within the ice are the principle agent transporting water from the highest to the underside of the ice sheet.

“Whereas lake drainages do all of a sudden pump a big quantity of water abruptly to the ice sheet, the truth is the quantity of water they put into the ice sheet is nearly trivial in contrast to the flux of water shifting by means of these intricate, very environment friendly drainage networks [of rivers] that unfold throughout the floor of the ablation [or melt] zone every summer time,” Smith mentioned.

In addition to contributing to sea stage rise, soften water runoff additionally accelerates ice loss: when the water percolates by means of the ice sheet and reaches the rock beneath, it barely lifts the ice, serving to it movement quicker towards the ocean. Additionally, the depth and space of floor soften are projected to enhance with local weather change.

The rise in decision of satellite tv for pc imagery over the last decade has allowed researchers to higher map soften water rivers and determine good candidates for area analysis. Nonetheless, it’s logistically very difficult to set camp on the soften zone: the Nationwide Science Basis coordinates the transport of apparatus and personnel to Greenland. Then, all researchers and instruments have to be helicoptered in from the closest city off the ice sheet – in Smith’s case, Kangerlussuaq, in western Greenland. Researchers usually have to transfer camp, for the reason that soften rapidly makes all the things too soggy. Extra importantly, the scientists go to nice lengths to guarantee security: had been anybody to slip and fall within the frigid waters, she or he can be rapidly swept away into the moulin with none risk of rescue, disappearing ceaselessly. For that reason, researchers should tether themselves to ropes when working close to the rivers.

The moulin close to Smith’s camp drained a catchment, or single community of streams flowing to a river, encompassing about 27 sq. miles (70 sq. kilometers) of the Greenland ice sheet. Because the river by the camp approached the sinkhole, its waters deeply lower into the ice partitions and carved a steep canyon. The group had marked the boundaries of no-go zones with brilliant orange tape, confining their information assortment to a secure flat riverbank. Nonetheless, the researchers had been roped in to keep away from falls whereas they moved again and forth throughout the waters an instrument referred to as an Acoustic Doppler Present Profiler, which bounced sound waves by means of the waters to measure the depth and velocity of the river’s movement.

Additional upstream, Smith deployed three autonomous drift boats outfitted with GPS and a number of different sensors. Because the devices floated down the river, they transmitted through satellite tv for pc their coordinates, plus temperature information and depth measurements taken with sonar, till they had been swallowed by the moulin.

The info will permit researchers to calculate the quantity of the water coming into the sinkhole. Smith’s group will use the sector measurements to calibrate distant estimates taken by satellites, comparable to the dual satellites of NASA’s Gravity Restoration and Local weather Experiment (GRACE) and the business WorldView spacecraft, and plane missions comparable to NASA’s Operation IceBridge. The sphere information will permit researchers to confirm the simulation of regional local weather fashions used to estimate future sea stage rise. They may also incorporate the distant and area measurements into a pc mannequin to create a simulation of soften water runoff processes working on the ice sheet.

Complementary Research

On July 19, Smith’s camp on the Greenland ice sheet had guests: researchers Marco Tedesco, an affiliate professor on the Metropolis School of New York, and Tom Mote, a climatologist at College of Georgia. The 2 scientists had been taking measurements of the albedo (the flexibility to replicate sunshine) of the basin. Albedo adjustments through the soften season as a result of soften makes the snow and ice crystals develop and grow to be much less reflective. On the identical time, darkish materials comparable to soot, mud and organic materials is darkening the floor of the ice. The darker the ice, the extra vitality it absorbs, which leads to extra melting.

From the helicopter, Tedesco and Mote had been flying the prototype of a brand new spectrometer – an instrument that measures the depth of photo voltaic gentle: first pointing it on the sky to calculate how a lot solar radiation was coming down, and then downward to see how a lot vitality the ice sheet was absorbing. The researchers had been additionally amassing geo-located, very high-resolution photos from a digital digicam mounted underneath the stomach of the helicopter.

Tedesco mentioned that he and Mote had been overlapping their information assortment with Smith’s area website as a result of the 2 tasks had been “very complementary.”

“They complement one another as a result of albedo is driving the melting, and the melting is producing the runoff that’s creating the rivers Larry research,” Tedesco mentioned. “We’re going to present Larry a really detailed map of albedo for this space, which he’ll use to higher perceive the place melting is extra intense or much less intense, and the place the water that’s feeding his streams and rivers is coming from.”

Mote, Tedesco and Smith’s analysis is simply a portion of the complementary analysis that NASA is funding this summer time in Greenland: the company gives funds for dozens of tasks that look into components such because the function of warming ocean waters in melting glaciers from beneath, or how the land rebounds because it sheds ice. All of them with an final objective: to enhance our data of how briskly and how a lot Greenland will affect sea stage rise within the upcoming many years.

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