Sentences with phrase «surface melting of the ice sheet»

Severinghaus played several roles in the NEEM project, but his principal contribution was to determine the extent of surface melting of the ice sheet using the ratios of certain gases trapped within bubbles in the ice.

Not exact matches

The Greenland ice sheet occupies about 82 % of the surface of Greenland, and if melted would cause sea levels to rise by 7.2 metres.

This allowed them to calculate the redistribution of mass on Earth's surface due to the melting of the Greenland and Antarctic ice sheets and mountain glaciers, and model the shift in Earth's axis.

«The fact that a large portion of the western flank of the Greenland ice sheet has become dark means that the melt is up to five times as much as if it was a brilliant snow surface.»

Box pointed to nearly ice - sheet - wide melting on Greenland, with extensive surface melting documented for first time at the highest elevations of ice sheet, and the longest melt season since satellite observations began in 1979.

The data allowed them to calculate the redistribution of mass on Earth's surface due to the melting of the Greenland and Antarctic ice sheets and mountain glaciers, and the resulting rise in sea level.

David Ullman, a postdoctoral researcher at Oregon State University and lead author on the study, said there are two mechanisms through which ice sheets diminish — dynamically, from the jettisoning of icebergs at the fringes, or by a negative «surface mass balance,» which compares the amount of snow accumulation relative to melting.

In Iceland, the Grimsvotn volcano, buried miles beneath the ice sheet, melts the ice cap above it in the same way that the rising plumes might melt Europa's shell, causing the surface of the Icelandic ice sheet to cave in.

Melting near the edges of the Greenland ice sheet, where the surface is below 4,000 feet, causes about half of its annual ice loss.

The great ice sheets of Greenland and Antarctica, which rise to over 13,000 feet above sea level, accumulate ice over most of their surfaces and melt only at their lower elevations near the edges.

And on July 11 - 12 last year, gusts of warm air caused melting on virtually the entire surface of the ice sheet.

However, it's quite a different matter melting a long - lived massive ice sheet up to 1.5 km thick that covers over 70 % of the land surface (as happened at the end of the last glacial period), from melting isolated and much thinner ice caps / sheets that only cover about 11 % of the land surface (i.e. present - day).»

The research published in Nature Communications found that in the past, when ocean temperatures around Antarctica became more layered - with a warm layer of water below a cold surface layer - ice sheets and glaciers melted much faster than when the cool and warm layers mixed more easily.

Estimates from the National Snow and Ice Data Center indicate that roughly half the ice sheet's surface is melting, well above the average of around 25 percent for this time of yeIce Data Center indicate that roughly half the ice sheet's surface is melting, well above the average of around 25 percent for this time of yeice sheet's surface is melting, well above the average of around 25 percent for this time of year.

Recent summers on the vast, white expanse of the Greenland ice sheet have featured some spectacular ice melt, including an alarming period in 2012 when nearly the whole surface showed signs of melt.

When an icy impact occurred, the impactor's kinetic energy became heat energy, instantly melted some ice, gouged out a crater, and kicked up into Mars» thin atmosphere large amounts of debris mixed with water (liquid, ice crystals, and vapor)-- and complex organic molecules that obviously came recently from life.127 Then, the dirt and salt - water mixture settled back to the surface in vast layers of thin sheets — strata — especially around the crater.

Unlike the great ice sheet of Antarctica, the Greenland ice sheet is melting both on its surface and also at outlet glaciers that drain the ice sheet's mass through deep fjords, where these glaciers extend out into the ocean and often terminate in dynamic calving fronts, giving up gigaton - sized icebergs at times.

Richard B. Alley, an expert on Greenland's ice sheet at Penn State, told me it's still possible that flows of meltwater from surface lakes could start large areas of ice moving seaward, particularly if the melt zones continue to expand inland as they have been doing for years now.

The problem with the paleoclimate ice sheet models is that they do not generally contain the physics of ice streams, effects of surface melt descending through crevasses and lubricating basal flow, or realistic interactions with the ocean.

Other factors would include: — albedo shifts (both from ice > water, and from increased biological activity, and from edge melt revealing more land, and from more old dust coming to the surface...); — direct effect of CO2 on ice (the former weakens the latter); — increasing, and increasingly warm, rain fall on ice; — «stuck» weather systems bringing more and more warm tropical air ever further toward the poles; — melting of sea ice shelf increasing mobility of glaciers; — sea water getting under parts of the ice sheets where the base is below sea level; — melt water lubricating the ice sheet base; — changes in ocean currents -LRB-?)

In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12.

The trait, he proposed, comes to the surface when such people confront strong messaging on the need for emissions reductions amid enduringly murky science on what's driving some particular extreme environmental phenomenon in the world — whether a brief period of widespread melting on the Greenland ice sheet, a potent drought, a tornado outbreak or the extreme event of the moment, the hybrid nor» easter / hurricane known on Twitter as #Frankenstorm.

Extent of surface melt over Greenland's ice sheet on July 8, 2012 (left), and July 12, 2012 (right).

They offered a conclusion that the «coupling between surface melting and ice - sheet flow provides a mechanism for rapid, large - scale, dynamic responses of ice sheets to climate warming».

The flow of news releases and background science content from NASA is generally excellent, but the space agency badly blew it earlier this week with this headline, which has now reverberated around the Web: «Satellites See Unprecedented Greenland Ice Sheet Surface Melt.»

Thicker ice sheets can be more resistant to melting by having colder surfaces (but also depress the crust more, so that when melting occurs, it may leave ocean instead of land (isostatic adjustment being a slow process — from memory, a timescale of ~ 15,000 years?)

What scientists once thought was a fairly simple linear process — that is, a certain amount at the surface of an ice sheet melts each year, depending on the temperature — is now seen to be much more complicated.

«Surface Melt - Induced Acceleration of Greenland Ice - Sheet Flow.»

We quantify sea - level commitment in the baseline case by building on Levermann et al. (10), who used physical simulations to model the SLR within a 2,000 - y envelope as the sum of the contributions of (i) ocean thermal expansion, based on six coupled climate models; (ii) mountain glacier and ice cap melting, based on surface mass balance and simplified ice dynamic models; (iii) Greenland ice sheet decay, based on a coupled regional climate model and ice sheet dynamic model; and (iv) Antarctic ice sheet decay, based on a continental - scale model parameterizing grounding line ice flux in relation to temperature.

25 Alastair noted, «But as Jim Hansen pointed out, once an ice sheet starts to melt there is plenty of water on the surface to produce humidity.»

Surface melt - induced acceleration of Greenland ice - sheet flow.

But as Jim Hansen pointed out, once an ice sheet starts to melt there is plenty of water on the surface to produce humidity.

As this week started, scientists monitoring the Greenland ice sheet experienced a shock - over 10 per cent of the island's ice sheet surface was experiencing melting of over 1 millimetre.

These satellite - derived maps show the extent of surface melt over Greenland's ice sheet during the summer of 2012...

DMI says, The surface mass balance is calculated over a year from September 1st to August 31st (the end of the melt season) For the 2016 - 17 SMB year, which ended yesterday, the ice sheet had gained 544bn tonnes of ice, compared to an average for 1981 - 2010 of 368bn tonnes.

Higher temperatures in polar regions and a decrease in the salinity of surface water due to melting ice sheets could interrupt such circulation, the report says.

Editor's note: Marco Tedesco, Sarah Doherty, and other coauthors of the work described above urged the scientific community in a recent opinion piece on Eos.org to quantify the roles of multiple factors — among them coarsening of snow, light - absorbing particles, and melt ponds — in the darkening of the Greenland ice sheet's surface and subsequent ice loss.

In the summer, they cause the surface of the ice - shelves to melt David Vaughan of the EU's ice2sea programme commented that, «this study shows very clearly why the Antarctic ice sheet is currently losing ice, which is a major advance.

For humanity itself, the greatest threat is the likely demise of the West Antarctic ice sheet as it is attacked from below by a warming ocean and above by increased surface melt.

And Dr Bougamont said: «There are two sources of net ice loss: melting on the surface and increased flow of the ice itself, and there is a connection between these mechanisms that isn't taken into account by standard ice sheet models.»

According to NOAA's 2012 Arctic Report Card, the duration of melting at the surface of the ice sheet in summer 2012 was the longest since satellite observations began in 1979, and the total amount of summer melting was nearly double the previous record, set in 2010 (satellite records of melting go back to 1979.)

The 16 July low was the lowest in the satellite observational record and coincided with 97 % of the ice sheet surface area melting.

A rare, near - ice sheet - wide surface melt event melted 97 % of the surface of Greenland's ice sheet on July 11 — 12.

During the most recent event, almost all of the ice sheet experienced surface melting.

The conventional view holds that sea levels will start to rise as a pulse of warming works its way gradually from the surface through the two kilometre - and three kilometre - thick ice sheets on Greenland and Antarctica and melts them.

Endless stories about glaciers melting, polar bears, ice sheets in Greenland and Antarctica and sea ice form the view that there is virtually no ice left on the surface of the planet.

«The Greenland ice sheet, which is up to 3000 + metres thick, is not «melting away», did not «melt in four days», it is not «melting fast», and Greenland did not «lose 97 per cent of its surface ice layer».»

Satellites that constantly scan environmental conditions on the planet's surface had revealed that from 8 July to 12 July, 97 per cent of the surface of the ice sheet contained water rather than ice, whereas typically just 45 per cent of the surface area melts at this time of year.

A massive ice sheet almost completely covers Greenland, and as summertime temperatures climb and sunlight hours lengthen, parts of the ice sheet surface usually melt, especially at lower elevations near the coast.

The summer of 2012 brought Greenland far more extensive melt than anything observed in the satellite record: in July 2012, surface melt extended over nearly the entire ice sheet.