Sentences with phrase «glacier grounding lines»

For this they used the latest observations of how glacier grounding lines have been changing.

For this they used the latest observations of how glacier grounding lines have been changing.

This would suggest to me that the glacier grounding line will retreat into the deeper basin upglacier of the current grounding line.

Not exact matches

Some glaciers on the perimeter of West Antarctica are receiving increased heat from deep, warm ocean currents, which melt ice from the grounding line, releasing the brake and causing the glaciers to flow and shed icebergs into the ocean more quickly.

Eventually, the floating ice shelf in front of the glaciers «broke up», which caused them to retreat onto land sloping downward from the grounding lines to the interior of the ice sheet.

The height of these cliffs made them unstable, triggering the release of thousands of icebergs into Pine Island Bay, and causing the glacier to retreat rapidly until its grounding line reached a restabilising point in shallower water.

Satellite data also helped them make a detailed map of grounding lines across Antarctica and determine where glaciers were retreating fastest.

The boundary between glacier and ice shelf is called a grounding line.

At the grounding line, the ice detaches from the bedrock and juts out into the water as a kind of floating ledge, or ice shelf, which helps to stabilize the glacier and hold back the flow of ice behind it.

The position of the grounding line can tell scientists a lot about the stability of any given glacier and its potential to contribute to sea - level rise.

At Pine Island Glacier, for instance — one of West Antarctica's largest glaciers, and previously one of its fastest retreating spots — the research suggests that the grounding line has recently stabilized.

But scientists increasingly attribute much of the observed grounding line retreat — particularly in West Antarctica — to the influence of warmer ocean water seeping beneath the ice shelves and lapping against the bases of glaciers, melting the ice from the bottom up.

The retreat of the grounding line at these glaciers is more than five times that rate.

Although CryoSat - 2 is designed to measure changes in the ice sheet elevation, these can be translated into horizontal motion at the grounding line using knowledge of the glacier and sea floor geometry and the Archimedes principle of buoyancy — which relates the thickness of floating ice to the height of its surface.

Most Antarctic glaciers flow straight into the ocean in deep submarine troughs, the grounding line is the place where their base leaves the sea floor and begins to float.

Between 2002 and 2007, satellite measurements showed that ice from the glacier's grounding line, the spot where it transitions from being on the land to in the sea, thinned at a rate of 1.2 meters to 6 meters per year.

If they begin to melt, however — particularly as they're exposed to warmer ocean water — the shelves become thinner and the grounding line begins to retreat backward, causing the glacier to become less stable and making the ice shelf more likely to break.

Lead author Dr Malcolm McMillan from the University of Leeds said: «We find that ice losses continue to be most pronounced along the fast - flowing ice streams of the Amundsen Sea sector, with thinning rates of between 4 and 8 metres per year near to the grounding lines of the Pine Island, Thwaites and Smith Glaciers.»

If a glacier loses mass from enhanced melting, it may start floating farther inland from its former grounding line, just as a boat stuck on a sandbar may be able to float again if a heavy cargo is removed.

For a separate study, the NASA Jet Propulsion Laboratory's Ala Khazendar — a co-author of Scheuchl's paper — measured ice loss at the bottom of the three glaciers, which he suspected might be influencing the changes in their grounding lines.

Radar waves penetrate glaciers all the way to their base, allowing direct assessment of how the bottom profiles of the three glaciers at their grounding lines differed between 2002 and 2014.

The grounding line is important because nearly all glacier melting takes place on the underside of this floating portion, called the ice shelf.

Khazendar and his team, analyzing their direct radar measurements, found stunning rates of ice loss from the glaciers» undersides on the ocean sides of their grounding lines.

The fastest - melting glacier, Smith, lost between 984 and 1,607 feet (300 and 490 meters) in thickness between 2002 and 2009 near its grounding line, or up to 230 feet (70 meters) per year.

Using satellites, the researchers determined that «bottom melt rates experienced by large outlet glaciers near their grounding lines are far higher than generally assumed.»

In Antarctica, dynamic thinning has accelerated at the grounding lines of the major glaciers of the Amundsen Sea embayment, and in places has penetrated to within 100 km of the ice divides.

Thwaites, meanwhile, also continues to rank among of the fastest - shrinking glaciers, and has seen its grounding line retreat rate increase slightly compared to the earlier period, which Konrad said «should emphasize once more that this glacier is under threat.»

In the somewhat good news department, the new study shows that Pine Island Glacier, the fastest - shrinking glacier on the planet, has actually seen its grounding line retreat slow down markedly compared to measurements taken from 1992 - 2011.

Grounding line recession here could be irreversible, leading to rapid glacier thinning and recession, and sea level rise — see Marine Ice Sheet Instability.

Additional data often mapped by satellite and added to glacier inventories include changing ice debris cover20, rock glaciers21, equilibrium line altitude22, grounding zones23 and glacial lake extent24, 25.

Schematic cartoon of a glacier flowing into an ice shelf, showing the grounding line and calving at the ice cliff at the edge of the ice shelf.

Once the ice shelf retreats to the grounding line, the buoyant force that used to offset glacier flow becomes negligible, and the glacier picks up speed on its way to the sea.

Satellites have provided grounding lines observations of Pine Island Thwaites glaciers (and other glaciers for that matter) since getting direct observations under the ice is basically a non-starter.

Warm waters have been eating away at ice from below in this region, and once grounding lines retreat far enough inland, entire glaciers can become unstable and collapse.

The rapid shrinkage of glaciers around the Antarctic Peninsula, coupled with the potential for ice - shelf collapse and grounding line retreat, raises concerns for the future of the West Antarctic Ice Sheet, and this is an area of urgent current research [3].

However, they also report that «the net change for all the glaciers, weighted by glacier width at the grounding line, has been [one of] advance» (emphasis added) with an average rate of increase of +12 ± 88 m yr - 1 (see Figure 1 below).

And sea level rise will affect the glaciers that have grounding lines upstream and under the ice — the grounding line moves further upstream... would this touch some of the deeper lakes under the ice cap?

First, as glaciers melt sea level rises and grounding lines retreat speeding the remaining glaciers» advance into the sea.

The other is the recognition that warming ocean temperatures at the grounding line for the glaciers is driving a really strong flow and thus melting response.

The grounding line is an anchoring point for the outlet glaciers.

Without a rise in the bed, glacier thinning and retreat could result in continual grounding line retreat.

There was a paper in Science several years back whose conclusion was that once glaciers left their terminal moraine grounding lines behind, the embayment left behind would freshen and cool with meltwater and provide a negative feedback to more melting.

That big hump probably was the terminal moraine of the glacier for substantial periods, and could be a potential end to the tipping point of runaway grounding line retreat.

The grounding line is where the bottom of the glacier comes in contact with the ground below the ice sheet, in this case the sea bottom.

The observed acceleration, retreat of the grounding line, thinning of the lower section of the glacier and the observed elevation of the basal topography provide no indication that this is not a weak underbelly of WAIS.

Change was afoot: after 50 years of apparent stability, the glacier calving front was retreating, and the grounding line was retreating indicating reduced bedrock anchoring.

If shortening the glacier increases the depth at the grounding line, increasing the rate of loss, the situation is unstable, and the loss accelerates.

«Widespread, Rapid Grounding Line Retreat of Pine Island, Thwaites, Smith and Kohler Glaciers, West Antarctica from 1992 to 2011.»

«More sections of the glacier become thinner and float, meaning that the grounding line continues retreating, and so on,» Khazendar explained in the statement.

Most of the increase occurred along West Antarctic grounding lines; East Antarctic glaciers remained very stable.