Sentences with phrase «of ice sheet mass»
This large acceleration explains a large share of the different GRACE estimates of ice sheet mass loss published in recent years.
http://www.realclimate.org/
... what are the shapes of the ice sheet mass loss curves for Greenland and West Antarctica?
Lots of Antarctic sea ice would argue that the loss of ice sheet mass is decreasing — however on the subject of sea ice and mass loss there is a lot of dancing.
As with IMBIE 2012, it will collate, compare, integrate, interpret, and report satellite estimates of ice sheet mass balance, with the overall aim of producing a community assessment of Greenland and Antarctica's ongoing contributions to global sea level rise.
In fact, there are now well over 150 individual assessments of ice sheet mass balance based on measurements acquired by at least 15 different satellite missions.
In light of these developments, it is now time for an updated community assessment of ice sheet mass balance.
The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering.
Our assumption that global temperature passed the Holocene mean a few decades ago is consistent with the rapid change of ice sheet mass balance in the past few decades [75].
The models are certainly wrong when it comes to simulating the rate of arctic sea ice loss, or the full dynamics of ice sheet mass balance changes.
Shepherd et al., 2012 A reconciled estimate of ice sheet mass balance.
That estimate was based in part on the fact that sea level is now rising 3.2 mm / yr (3.2 m / millennium)[57], an order of magnitude faster than the rate during the prior several thousand years, with rapid change of ice sheet mass balance over the past few decades [23] and Greenland and Antarctica now losing mass at accelerating rates [23]--[24].
For Antarctica as a whole, the study found the current rate of ice sheet mass loss to be about 160 billion metric tons of ice per year.
Then in 2003 the launch of two new satellites, ICESat and GRACE, led to vast improvements in one of the methods for mass balance determination, volume change, and introduced the ability to conduct gravimetric measurements of ice sheet mass over time.
The software developed will combine individual assessments of ice sheet mass balance to determine a reconciled estimate of ice sheet mass balance, taking into account the spatial and temporal domain of the input data and their uncertainties, and generate summary graphical and tabulated output.
That estimate was based in part on the fact that sea level is now rising 3.2 mm / yr (3.2 m / millennium)[57], an order of magnitude faster than the rate during the prior several thousand years, with rapid change of ice sheet mass balance over the past few decades [23] and Greenland and Antarctica now losing mass at accelerating rates [23]--[24].
His comments are based on the paper «Limits in detecting acceleration of ice sheet mass loss due to climate variability», B. Wouters, J. L. Bamber, M. R. van den Broeke, J. T. M. Lenaerts and I. Sasgen, Nature Geoscience 6, 613 — 616 (2013) doi: 10.1038 / ngeo1874 Find the abstract and illustrations for that paper here.
Not exact matches
Understanding sea level change in relation to the mass balance of Greenland's and Antarctica's ice sheets is at the heart of the CReSIS mission.
As glaciologist Richard Alley of Pennsylvania State University notes: «The ice sheet is losing mass, this loss has increased over time, [and] it is not the dominant term in sea - level rise — but it matters.»
Estimated changes in the mass of Greenland's ice sheet suggest it is melting at a rate of about 239 cubic kilometres (57.3 cubic miles) per year.
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.
Today, as warming waters caused by climate change flow underneath the floating ice shelves in Pine Island Bay, the Antarctic Ice Sheet is once again at risk of losing mass from rapidly retreating glacieice shelves in Pine Island Bay, the Antarctic Ice Sheet is once again at risk of losing mass from rapidly retreating glacieIce Sheet is once again at risk of losing mass from rapidly retreating glaciers.
What they found, Hansen says, is that melting ice sheets in Greenland and Antarctica could inject enough fresh water into the seas to slow the formation of two key water masses: the North Atlantic Deepwater and the Antarctic Bottom Water formations.
The drought that is devastating California and much of the West has dried the region so much that 240 gigatons worth of surface and groundwater have been lost, roughly the equivalent to a 3.9 - inch layer of water over the entire West, or the annual loss of mass from the Greenland Ice Sheet, according to the study.
To better understand and anticipate changes in sea level rise, scientists have sought to quantify how much snow falls on the ice sheet in any given year, and where, since snow is the primary source of the ice sheet's mass.
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.
«What we found was that during most of the deglaciation, the surface mass balance of the Laurentide Ice Sheet was generally positive,» Ullman said.
«This is probably the best method to look at mass changes of ice sheets if you want to get a number that you can trust,» Rignot says.
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.
When the Gravity Recovery and Climate Experiment (GRACE) satellites began measuring gravity signals around the world in 2002, scientists knew they would have to separate mass flow beneath the earth's crust from changes in the mass of the overlying ice sheet.
«By refining the spatial pattern of mass loss in the world's second largest — and most unstable — ice sheet, and learning how that pattern has evolved, we are steadily increasing our understanding of ice loss processes, which will lead to better - informed projections of sea level rise.»
«It doesn't change our estimates of the total mass loss all over Greenland by that much, but it brings a more significant change to our understanding of where within the ice sheet that loss has happened, and where it is happening now.»
The argument is that the increased separation of the Antarctic land mass from South America led to the creation of the powerful Antarctic Circumpolar Current which acted as a kind of water barrier and effectively blocked the warmer, less salty waters from the North Atlantic and Central Pacific from moving southwards towards the Antarctic land mass leading to the isolation of the Antarctic land mass and lowered temperatures which allowed the ice sheets to form.
Measurements of local gravitational anomalies by the GRACE satellites show that the Greenland ice sheet, particularly in its southern reaches, is rapidly losing mass.
«Once you have that combination of ocean heat and atmospheric heat — which are related — that's when the ice sheet could really experience dramatic ice mass loss.»
In other words, the losses of mass of the West Antarctic Ice Sheet will intensify — just like the models predict.»
The melting of Greenland contributes to the global sea level, but the loss of mass also means that the ice sheet's own gravitational field weakens and thus does not attract the surrounding sea as strongly.
The East Antarctic ice sheet is the largest ice mass on Earth, roughly the size of Australia.
The second is the gravity method, which utilizes NASA's GRACE satellite pair to essentially weigh the ice sheets from space (it measures minute changes in their flight path due to the shifting gravity field of mass below).
«The fact that the mass loss of the Greenland Ice Sheet has generally increased over the last decades is well known,» Khan said, «but the increasing contribution from the northeastern part of the ice sheet is new and very surprising.&raqIce Sheet has generally increased over the last decades is well known,» Khan said, «but the increasing contribution from the northeastern part of the ice sheet is new and very surprising.&rSheet has generally increased over the last decades is well known,» Khan said, «but the increasing contribution from the northeastern part of the ice sheet is new and very surprising.&raqice sheet is new and very surprising.&rsheet is new and very surprising.»
But that could soon change, Rignot said, because the rate at which ice sheets are losing mass is increasing three times faster than the rate of ice loss from mountain glaciers and ice caps.
Subtracting one from the other produced a «mass - balance» picture of net ice loss or growth for each ice sheet.
GNET, short for «Greenland GPS Network,» uses Earth's natural elasticity to measure the mass of the ice sheet.
The Cordilleran Ice Sheet covered large parts of North America during the Pleistocene - or last ice age - and was similar in mass to the Greenland Ice SheIce Sheet covered large parts of North America during the Pleistocene - or last ice age - and was similar in mass to the Greenland Ice Sheice age - and was similar in mass to the Greenland Ice SheIce Sheet.
Although that is unlikely to happen for many thousands of years, the ice sheet has increasingly lost mass over the last two decades, and the glaciers that serve as its outlet to the sea are accelerating.
Despite being trumpeted in certain circles as meaning that there's really nothing to worry about regarding the Greenland ice sheet, the authors made a point of noting (although not in this press release) that an additional source of mass loss needs to be identified in order to reconcile their results with the GRACE data (which do not show a reduction in mass loss for the same period).
First, the loss of mass in the Antarctic ice sheet is actually somewhat unexpected.
The relevant papers are [Velicogna and Wahr 2006 Measurements of time - variable gravity show mass loss in Antarctica Science 311, 1754 - 1756 and Rignot and Thomas «Mass balance of polar ice sheets» Science 297, 1502 - 1506]
A pair of satellites (GRACE) were launched several years ago to determine mass balance in the Antarctic and Greenland ice sheets.
The rebound can be used to weigh the ice sheet and determine how much mass it has lost and is currently losing, said Doug Wiens, PhD, professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis.
The reconstructed curve includes isolated rapid events of several decimetres within a few centuries, one of which is most likely related to loss from the Antarctic ice sheet mass around 5000 years before present.