Sentences with phrase «by ice sheet models»

Not exact matches

«The widespread loss of Antarctic ice shelves, driven by a warming ocean or warming atmosphere, could spell disaster for our coastlines — and there is sound geological evidence that supports what the models are telling us,» said Robert M. DeConto of the University of Massachusetts Amherst, a co-author of the study and one of the developers of the ice - sheet model used.

Computer model simulations have suggested that ice - sheet melting through warm water incursions could initiate a collapse of the WAIS within the next few centuries, raising global sea - level by up to 3.5 metres.»

Recent modelling by researchers from the Potsdam Institute for Climate Impact Research in Germany, as well as studies of past climate, suggest that the planet will soon have warmed enough to melt Greenland's ice sheet entirely — if it hasn't already become warm enough.

Over the current century, the model projects that the average albedo for the entire ice sheet will fall by as much as 8 percent, and by as much 10 percent on the western edge, where the ice is darkest today.

The paper also describes an atmosphere - ocean modeling study of feedback loops caused by ice sheet melting under 2 °C conditions.

Research by the UK Centre for Polar Observation and Modelling (CPOM) at the University of Leeds has produced the first complete map of how the ice sheet's submarine edge, or «grounding line,» is shifting.

The international team of co-authors, led by Peter Clark of Oregon State University, generated new scenarios for temperature rise, glacial melting, sea - level rise and coastal flooding based on state - of - the - art climate and ice sheet models.

By 2100, the choice of driving climate model conditions dominates the uncertainty, but by 2200, the uncertainty in the ice sheet model and the elevation scheme are largeBy 2100, the choice of driving climate model conditions dominates the uncertainty, but by 2200, the uncertainty in the ice sheet model and the elevation scheme are largeby 2200, the uncertainty in the ice sheet model and the elevation scheme are larger.

By combining satellite images of the ice sheet and wind stress data from observations and computer modeling, Greene and his collaborators were able to study the chain of events that brings the warm water to Totten.

The international research initiative IceGeoHeat led by the GFZ German Research Centre for Geosciences establishes in the current online issue of Nature Geoscience that this effect can not be neglected when modeling the ice sheet as part of a climate study.

In the study, researchers analyzed a series of transient Coupled General Circulation Model simulations forced by changes in greenhouse gases, orbital forcing, meltwater discharge and the ice - sheet history throughout the past 21,000 years.

The consequences of global sea level rise could be even scarier than the worst - case scenarios predicted by the dominant climate models, which don't fully account for the fast breakup of ice sheets and glaciers, NASA scientists said today (Aug. 26) at a press briefing.

Summer surface meltwater will expand vertical fractures in the ice sheet and lubricate the ice sheet bed, so leading to mechanical breakup by mechanisms that we currently can not model by computer and so can not forecast.

The heights of the rectangular bars denote best estimate values guided by published values of the climate change agents and conversion to radiative perturbations using simplified expressions for the greenhouse gas concentrations and model calculations for the ice sheets, vegetation and mineral dust.

For example, some exciting work being done by David Pollard and Rob DeConto suggests that processes such as ice - cliff collapse and ice - shelf hydrofracturing may play important roles in future ice sheet behavior that have not been well incorporated into most ice sheet models.

A new study combines the latest observations with an ice sheet model to estimate that melting ice on the Antarctic ice sheet is likely to add 10 cm to global sea levels by 2100, but it could be as much as 30 cm.

i would much rather discuss and learn about cloud models, ocean circulation, ice sheet stability than repeatedly counter ignorant arguments by innumerate dunces.

One recent modeling study focused on this mode of instability estimated that the Antarctic ice sheet has a 1 - in - 20 chance of contributing about 30 centimeters (1.0 feet) to global average sea - level rise over the course of this century and 72 centimeters (2.4 feet) by the end of the next century.

Gallée, H., et al., 1991: Simulation of the last glacial cycle by a coupled, sectorally averaged climate — ice sheet model.

Model studies for climate change between the Holocene and the Pliocene, when Earth was about 3 °C warmer, find that slow feedbacks due to changes of ice sheets and vegetation cover amplified the fast feedback climate response by 30 — 50 % [216].

Such close linkages between CO2 concentration and climate variability are consistent with modelling results suggesting with high confidence that glacial — interglacial variations of CO2 and other greenhouse gases [CH4, N2O] explain a considerable fraction of glacial — interglacial climate variability in regions not directly affected by the northern hemisphere continental ice sheets (Timmermann et al., 2009; Shakun et al., 2012).

These results confirm behaviour predicted by climate models showing that greater snow cover should occur in this ice sheet.

«This uncertainty is illustrated by Pollard et al. (2015), who found that addition of hydro - fracturing and cliff failure into their ice sheet model increased simulated sea level rise from 2 m to 17 m, in response to only 2 °C ocean warming and accelerated the time for substantial change from several centuries to several decades.»

But what the GSL now says is that geological evidence from palaeoclimatology (studies of past climate change) suggests that if longer - term factors are taken into account, such as the decay of large ice sheets, the Earth's sensitivity to a doubling of CO2 could itself be double that predicted by most climate models.

(By the way, the I.P.C.C. didn't exclude the ice - sheet dynamics but they did say that the models currently were not good enough to do anything but to linearly extrapolate, and therefore they simply assumed the flow from Greenland and Antarctica based on the period 1993 - 2003.)

In LGM simulations land albedo changes are prescribed (at least in regards to ice sheets and altered topography due to sea level; there are feedback land albedo changes) so are a forcing, whereas sea ice is determined interactively by the model climate, so is a feedback in this framework.

In a more recent paper, our own Stefan Rahmstorf used a simple regression model to suggest that sea level rise (SLR) could reach 0.5 to 1.4 meters above 1990 levels by 2100, but this did not consider individual processes like dynamic ice sheet changes, being only based on how global sea level has been linked to global warming over the past 120 years.

Along with David Schilling, I had developed a model to reconstruct former ice sheets with ice elevations based on the strength of ice - bed coupling determined by glacial geology.

Combined climate / ice sheet model estimates in which the Greenland surface temperature was as high during the Eemian as indicated by the NEEM ice core record suggest that loss of less than about 1 m sea level equivalent is very unlikely (e.g. Robinson et al. (2011).

• Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise.

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.

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 vulnerability of the ice sheets to warming could be increased by dynamical processes related to ice flow (not included in current models but suggested by recent observations) thereby increasing future sea level rise.

These authors use an ice sheet model within a Bayesian statistical framework — in which critical processes are guided by expert synthesis — to simulate the mass loss from the entire Antarctic ice sheet to 2200.

Arctic air temperatures are increasing at twice the rate of the rest of the world — a study by the U. S. Navy says that the Arctic could lose its summer sea ice by next year, eighty - four years ahead of the models — and evidence little more than a year old suggests the West Antarctic Ice Sheet is doomed, which will add between twenty and twenty - five feet to ocean leveice by next year, eighty - four years ahead of the models — and evidence little more than a year old suggests the West Antarctic Ice Sheet is doomed, which will add between twenty and twenty - five feet to ocean leveIce Sheet is doomed, which will add between twenty and twenty - five feet to ocean levels.

One of the most feared of all model - based projections of CO2 - induced global warming is that temperatures will rise to such a degree as to cause a disastrous melting / destabilization of the Greenland Ice Sheet (GrIS), which melting is subsequently projected to raise global sea level by several meters.

A goal of 2C as calculated by current models is not protective of permafrost, clathrates, or ice sheets on a 50 year planning horizon from time of crossing the 1C mark.

To assure the model was realistic, the scientists drew on observations of changes in the altitude of the ice sheet surface made by NASA's IceSat satellite and airborne Operation IceBridge campaign.

They used the Ice Sheet System Model (ISSM), a numerical depiction of the physics of ice sheets developed by scientists at JPL and the University of California, IrviIce Sheet System Model (ISSM), a numerical depiction of the physics of ice sheets developed by scientists at JPL and the University of California, Irviice sheets developed by scientists at JPL and the University of California, Irvine.

Simulating the variation of the ice sheet's albedo using a regional climate model — Modèle Atmosphérique Régionale (MAR), which some members of the team helped develop — indicated that increasing temperatures and melting accompanied by snow grain growth and greater bare ice exposure account for about half the decline, the scientists report.

It is surprising, therefore, that the gross underestimation of pole ward energy transport by the computer models is not reflected as cooling and expansion of the ice sheets over the polar regions.

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.»

Mengel's team projected future sea levels by combining the results of models that anticipate changes to icebergs, ice sheets and ocean expansion in the years ahead, and used those findings to predict sea levels.

And older climate models did not include dynamic ice sheet vulnerabilities — like high latent - heat ocean water coming into contact with the submerged faces of sea - fronting glaciers, the ability of surface melt water to break up glaciers by pooling into cracks and forcing them apart (hydrofracturing), or the innate rigidity and frailty of steep ice cliffs which render them susceptible to rapid toppling.

Reducing these uncertainties by improving models of the processes that cause ice sheets to lose mass is, therefore, a critical goal of Earth Science research.

Model studies for climate change between the Holocene and the Pliocene, when Earth was about 3 °C warmer, find that slow feedbacks due to changes of ice sheets and vegetation cover amplified the fast feedback climate response by 30 — 50 % [216].

Bamber has recalculated the critical threshold temperature for ice sheet melting by forcing two surface mass balance models with real future climate.

These CO2 amounts are smaller than suggested by ice sheet / climate models, providing further indication that the ice sheet models are excessively lethargic, i.e. resistant to climate change.

Sea level from equations (3.3) and (3.4) is shown by the blue curves in figure 2, including comparison (figure 2c) with the Late Pleistocene sea - level record of Rohling et al. [47], which is based on analysis of Red Sea sediments, and comparison (figure 2b) with the sea - level chronology of de Boer et al. [46], which is based on ice sheet modelling with the δ18O data of Zachos et al. [4] as a principal input driving the ice sheet model.

Geological evidence from studies of past climate change now suggests that if longer term factors are taken into account, such as the decay of large ice sheets and the operation of the full carbon cycle, the sensitivity of the Earth to a doubling of CO2 could be double that predicted by most climate models.