Sentences with phrase «ice sheet mass changes»

Data for the modern rate of annual ice sheet mass changes indicate an accelerating rate of mass loss consistent with a mass loss doubling time of a decade or less (Fig. 10).

The most - optimal values for changes in bedrock elevation (GIA) in response to ice sheet mass changes have to be used

«A high - resolution record of Greenland mass balance» «Antarctica, Greenland and Gulf of Alaska land - ice evolution from an iterated GRACE global mascon solution» «Greenland and Antarctica ice sheet mass changes and effects on global sea level»

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.

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.

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.

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.

«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.

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.

«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 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).

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.

Mitrovica, J. X., Tamisiea, M. E., Davis, J. L. & Milne, G. A. Recent mass balance of polar ice sheets inferred from patterns of global sea - level change.

This implies that large - scale observations — for example, of global mean sea - level change or of the change mass of the Antarctic ice sheet — will not on their own significantly narrow the range of late - century sea - level projections for decades to come.

This spring, NASA and the German Research Centre for Geosciences are scheduled to launch the Gravity Recovery and Climate Experiment Follow - On (GRACE - FO) mission, twin satellites that will continue the original GRACE mission's legacy of tracking fluctuations in Earth's gravity field in order to detect changes in mass, including the mass of ice sheets and aquifers.

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].

The latter is almost linearly related to changes in ice sheet volume; the former, however, is influenced by a range of factors, including atmosphere / ocean dynamics and changes in Earth's gravitational field, rotation, and crustal and the mantle deformation associated with the redistribution of mass between land ice and the ocean.

So does mass change at the Earth's surface, which can come from shifts in ice sheets, or even possibly in major atmospheric wind currents.

And this is just one element in the sea level rise — small ice caps are melting faster, thermal expansion will increase in line with ocean heat content changes and Antarctic ice sheets are also losing mass.

From recent instrumental observations alone we are therefore unable to predict whether mass loss from these ice sheets will vary linearly with changes in the rate of sea - level rise, or if a non-linear response is more likely.

I do think it has been clear for a while that interactions with the ocean provide the greatest potential for surprises and rapid changes, and that Greenland's ice sheet would mostly pull out of the ocean before it lost most of its mass.

The satellites measure changes in gravity to determine mass variations of the entire Antarctic ice sheet.

The GRACE data offers a complete picture of the entire ice sheet, allowing comparisons of mass changes in coastal regions (eg - elevations below 2000 metres) with the Greenland interior (above 2000 metres).

Figure 3: Estimated ice mass change over time for the entire Antarctic ice sheet, West Antarctica, West Antarctica without the rapidly changing Amundsen Sea Coast (ASC) region and East Antarctica.

Postscript: A grouping of 40 + scientists, including four of our Nature co-authors, participated in the NASA / ESA Ice Sheet Mass Balance Intercomparison project (IMBIE) in an attempt to understand the reasons for previously disparate ice mass change estimatIce Sheet Mass Balance Intercomparison project (IMBIE) in an attempt to understand the reasons for previously disparate ice mass change estimatice mass change estimates.

We used an ensemble of ice sheet model runs and plausible Earth models to place bounded constraints on our mass change estimate.

Because ice sheets contain so much ice and have the potential to raise or lower global sea level so dramatically, measuring the mass balance of the ice sheets and tracking any mass balance changes and their causes is very important for forecasting sea level rise.

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.

At the beginning of the 1990s, scientists were unsure of the sign (positive or negative) of the mass balance of Greenland or Antarctica, and knew only that it could not be changing rapidly relative to the size of the ice sheet.

Figure 2: Ice mass changes for the Antarctic ice sheet from April 2002 to February 20Ice mass changes for the Antarctic ice sheet from April 2002 to February 20ice sheet from April 2002 to February 2009.

«These changes on the Greenland ice sheet are happening fast, and we are definitely losing more ice mass than we had anticipated,» said Isabella Velicogna, lead author of the study last year.

Figure 2: Time series of ice mass changes for the Greenland ice sheet estimated from GRACE monthly mass solutions for the period from April 2002 to February 2009.

To assess these implications, we translate global into local SLR projections using a model of spatial variation in sea - level contributions caused by isostatic deformation and changes in gravity as the Greenland and Antarctic ice sheets lose mass (36 ⇓ — 38), represented as two global 0.5 ° matrices of scalar adjustment factors to the ice sheets» respective median global contributions to SLR and (squared) to their variances.

The map shows the distribution of glaciers on the European continent, Svalbard, Iceland and in the periphery of the Greenland Ice Sheet together with the locations of glaciers with long - term mass change measurements.

«Models traditionally have projected that this difference doesn't become negative (i.e. net loss of Antarctic ice sheet mass) for several decades,» Mann said, adding that detailed gravimetric measurements, which looks at changes in Earth's gravity over spots to estimate, among other things, ice mass.

Hanna, E., Navarro, F., Pattyn, F., Domingues, C., Fettweis, X., Ivins, E., Nicholls, R., Ritz, C., Smith, B., Tulaczyk, S.... (2013) Ice - sheet mass balance and climate change.

In addition, the running sum total of the accumulated mass change over the Greenland Ice Sheet is shown on a graph overlay in gigatons.

Since its launch in 2002, GRACE has provided a continuous record of changes in the mass of the Earth's ice sheets.

A leading theory, presented by Dr. Bill McGuire, Hugh Tuffin, J. Maclennan, Peter Huybers and many others is that changes in stress to the Earth's crust caused by the loss of billions of tons of mass by ice sheets and the displacement of those billions of tons into the world's ocean system spurred previously stable magma systems into a chaotic displacement.

«The observed changes in sea ice on the Arctic Ocean, in the mass of the Greenland ice sheet and Arctic ice caps and glaciers over the past 10 years are dramatic and represent an obvious departure from long - term patterns,» says the report.

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].

«This implies that changes at the margin can affect the mass balance deep in the centre of the ice sheet,» said Dr Khan.

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.

Mass Gains of the Antarctic Ice Sheet Exceed Losses http://ntrs.nasa.gov/search.jsp?R=20120013495 SCAR ISMASS Workshop, July 14, 2012 «During 2003 to 2008, the mass gain of the Antarctic ice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt / yr (2.5 % of input), as derived from ICESat laser measurements of elevation chaIce Sheet Exceed Losses http://ntrs.nasa.gov/search.jsp?R=20120013495 SCAR ISMASS Workshop, July 14, 2012 «During 2003 to 2008, the mass gain of the Antarctic ice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt / yr (2.5 % of input), as derived from ICESat laser measurements of elevation cSheet Exceed Losses http://ntrs.nasa.gov/search.jsp?R=20120013495 SCAR ISMASS Workshop, July 14, 2012 «During 2003 to 2008, the mass gain of the Antarctic ice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt / yr (2.5 % of input), as derived from ICESat laser measurements of elevation chaice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt / yr (2.5 % of input), as derived from ICESat laser measurements of elevation csheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt / yr (2.5 % of input), as derived from ICESat laser measurements of elevation chaice discharge by 49 Gt / yr (2.5 % of input), as derived from ICESat laser measurements of elevation change

As Earth became colder and continental ice sheets grew, further increase of δ18O was due in equal parts to deep ocean temperature change and ice mass change.

According to the most highly - cited analyses of polar ice sheet melt and contribution to sea level rise, the Antarctic ice sheet as a whole changed in mass by -71 gigatonnes (GT) per year between 1992 and 2011.

The most recent calculations of ice mass balance in the antarctic also do indicate loss of ice, though nothing close to the changes seen in the arctic sea ice and Greenland ice sheet.

Great progress has been made recently in assessing the current rate of mass loss from the ice sheets (Shepherd et al., 2012), as well as monitoring the changing snowfall, surface melting, and temperature contributing to the changes.

In 2007, Denmark launched the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) to assess changes in the mass balance of the ice sheIce Sheet (PROMICE) to assess changes in the mass balance of the ice sSheet (PROMICE) to assess changes in the mass balance of the ice sheice sheetsheet.

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].