Sentences with phrase «ice sheet surface melting»

In that period ice sheet surface melting increased from 40 to 97 percent.

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.»

Does sea ice influence Greenland ice sheet surface melt?

Arctic sea ice extent reconstruction - Kinnard et al. 2011 Sea ice albedo feedback - NASA Polar jet stream - NC State University Greenland ice sheet surface melt - NASA Permafrost distribution in the Arctic - GRID - Arendal Atmospheric methane concentration - NOAA ESRL Russia plants flag at North Pole - Reuters

These rising temperatures have been accompanied by unprecedented Greenland ice sheet surface melt.

An estimated 97 percent of the ice sheet surface melted on July 11 and 12, 2012, and virtually the entire ice sheet surface melted at some point in July 2012.

Not only did Greenland Ice Sheet surface melt in 2012 occur over a bigger - than - average area, it also began about two weeks earlier at lower elevations and, for any given elevation, lasted longer.

I followed the link in wrsc to Satellite Data Indicates Unprecedented Greenland Ice Sheet Surface Melt.

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.»

As many surface melt - water lakes form each summer around the Greenland ice sheet, the possibility exists that similar subglacial lakes may be found elsewhere in Greenland.

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.

For millennia, Greenland's ice sheet reflected sunlight back into space, but satellite measurements in recent years suggest the bright surface is darkening, causing solar heat to be absorbed and surface melting to accelerate.

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.

The ice sheet got hammered by surface melt, and that's what drove final deglaciation.»

The two main forces that conspire to destroy Earth's massive polar ice sheets are heat, which melts their surfaces via sunlight and warm air, and gravity, which drives glaciers to slide to the sea.

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.

And summer is prime melt season, when the sun's rays beat down on the ice, causing meltwater to pool on the surface and drain down through the ice sheet and out to sea.

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.

In Antarctica, there is only occasional surface melt in the West Antarctic ice Sheet but the warmer seas around the edges should help unstick ice that has already pushed into the oceans.

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».

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?)

Surface melt on the ice sheet is constrained by the albedo, but a lake is dark and could absorb much more solar radiation.

• Current global model studies project that the Antarctic ice sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall.

Finally, there is another way how ice sheets can contribute to sea level rise: rather than melting at the surface, they can start to flow more rapidly.

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.»

All ice types, including massive ice sheets, mountain glaciers and Arctic sea ice (frozen sea - surface), are for the most part melting far faster than predicted three years ago.

Surface melt on an ice sheet not only directly reduces the ice sheet mass but also can accelerate ice flow and even leads to further melting.

NSIDC's Greenland Ice Sheet Today: Satellite images and information about surface melting on the Greenland ice shIce Sheet Today: Satellite images and information about surface melting on the Greenland ice Sheet Today: Satellite images and information about surface melting on the Greenland ice shice sheetsheet

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.