Sentences with phrase «with ice sheet modelling»

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.

Thus, as an extreme alternative that can be compared with ice sheet models and real - world data, we assume that hysteresis effects are negligible in our approximation for sea level as a function of temperature.

Not exact matches

The team used the new scheme in five ice sheet models and forced them with climate warming conditions taken from two different climate models.

What's left to figure out is whether this is happening with other subglacial lakes around the Greenland ice sheet, as well as whether and how to incorporate the findings into models that are aimed at gauging how much Greenland might change with the warming climate and how much water it could add to the rising seas.

But most of all, she wanted to know whether Pappalardo's model of Europa's ice sheet jibed with all he had learned from almost 30 years of studying ice on Earth.

When the researchers compared their results with the output of a number of climate models, they found that several of the newer models that have higher resolution and use updated ice sheet configurations do «a very good job» of reproducing the patterns observed in the proxy records.

Dr Ian Joughin at the University of Washington, author of a recent study simulating future Antarctic ice sheet losses added: «This study does a nice job of revealing the strong thinning along the Amundsen Coast, which is consistent with theory and models indicating this region is in the early stages of collapse.»

«The primary uncertainty in sea level rise is what are the ice sheets going to do over the coming century,» said Mathieu Morlighem, an expert in ice sheet modeling at the University of California, Irvine, who led the paper along with dozens of other contributors from institutions around the world.

To get the big picture right, however, we need models that physically couple ice sheets / shelves with the ocean.

To get their results the researchers used sophisticated ice sheet and climate models and verified their results with independent geological observations from the oceans off Antarctica.

Armed with aerial photos that reveal these trimlines, the researchers mapped the past and present sizes of the ice sheet in a 3D computer model.

Joughin et al. (2010) applied a numerical ice sheet model to predicting the future of PIG, their model suggested ongoing loss of ice mass from PIG, with a maximum rate of global sea level rise of 2.7 cm per century.

She has shown, in an ice sheet model with gravitationally self - consistent sea level, there is actually a sea level fall at the grounding line, which acts to stabilize against the marine ice sheet instability.

Statements such as «They come to believe models are real and forget they are only models» reveals he has never had a conversation with a climate modeller — our concerns about ice sheets for instance come about precisely because we aren't yet capable of modelling them satisfactorily.

This setup consists of an atmospheric model with a simple mixed - layer ocean model, but that doesn't include chemistry, aerosol vegetation or dynamic ice sheet modules.

Our modelled values are consistent with current rates of Antarctic ice loss and sea - level rise, and imply that accelerated mass loss from marine - based portions of Antarctic ice sheets may ensue when an increase in global mean air temperature of only 1.4 - 2.0 deg.

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.

And it is inspiring to see such progress being made in the detail with which models of ice sheet dynamics and other forms of change can be applied to the moderately far future.

Models actually predict that the interior of the ice sheets should gain mass because of the increased snowfall that goes along with warmer temperatures, and recent observations actually agree with those predictions.

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).

That rate is not consistent with a top down melting model and implies dynamic response of ice sheets to warming.

The sea - level estimates are consistent with those from delta18O curves and numerical ice sheet models, and imply a significant sensitivity of the WAIS and the coastal margins of the EAIS to orbital oscillations in insolation during the Mid-Pliocene period of relative global warmth.

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.

For example, Hansen's recent paper on Scientific Reticence is quite explicit that much of important physics of ice sheets is not included in the models, hence his raising of matters to do with nonlinear behaviour (eg disintegration) of ice sheets.

This is computed from an ice sheet surface mass balance model, with the snowfall amounts and temperatures derived from a high - resolution atmospheric circulation model.

On unreliability of models see O'Reilly et al. (2012), pp. 721 - 22; «there is still no robust, credible model for the interaction of melting ice sheets with the ocean,» Holland and Holland (2015).

With a much - needed GRACE follow - on mission being planned and expected to launch around 2017, observation and modelling of Antarctic GIA will continue to give us insights into the ice sheet history — from the LGM through to the present — and hence provide the context for any future changes.

The results are very conservative because they exclude the possibility of rapid changes of the ice sheets as the numerical models do not yet know how to deal with those.

Together with the University of Alaska, PIK develops the Parallel Ice Sheet Model (PISM), an innovative computer model of continental ice sheet dynamiIce Sheet Model (PISM), an innovative computer model of continental ice sheet dynaSheet Model (PISM), an innovative computer model of continental ice sheet dynaModel (PISM), an innovative computer model of continental ice sheet dynamodel of continental ice sheet dynamiice sheet dynasheet dynamics.

Probabilistic projections with the box model allowed consideration of all major uncertainties, such as modeled temperature sensitivities to CO2 concentrations, Greenland Ice Sheet melt sensitivities to temperature changes, and AMOC sensitivities to both temperature and Greenland Ice Sheet melt changes.

Pfeiffer, M. & Lohmann, G. Greenland ice sheet influence on last interglacial climate: global sensitivity studies performed with an atmosphere — ocean general circulation model.

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.

On the other side, Professor Andr e Berger and colleagues developed a mathematical model of the climate system, rated today as a «model of intermediate complexity» [6, 7] to solve the dynamics of the atmosphere and ice sheets on a spatial grid of 19 × 5 elements, with a reasonably extensive treatment of the shortwave and longwave radiative transfers in the atmosphere.

The main reason is that there is still no robust, credible model for the interaction of melting ice sheets with the ocean.

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

We find the Pliocene sea level varying between about +20 m and − 50 m, with the Early Pliocene averaging about +15 m; the ice sheet model has a less variable sea level with the Early Pliocene averaging about +8 m.

But «These models can not explain the high sea levels in the Pliocene period [from 5.3 million to 2.5 million years ago, which began warm and with high sea levels, but cooled towards the end], for example, where data point at a less stable Antarctic ice sheet than in the current models.»

For their study, Hansen and his colleagues combined ancient paleo - climate data with new satellite readings and an improved model of the climate system to demonstrate that ice sheets can melt at a «non-linear» rate: rather than an incremental melting as Earth's poles inexorably warm, ice sheets might melt at exponential rates, shedding dangerous amounts of mass in a matter of decades, not millennia.

Nevertheless, improvements in ice - sheet models over recent decades have led to closer agreement with satellite observations, keeping track with their increasing contribution to global sea - level rise.

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.

Thus, our simple transparent calculation may provide a useful comparison with geological data for sea - level change and with results of ice sheet models.

More elaborate and accurate approaches, including use of models, will surely be devised, but comparison of our result with other approaches is instructive regarding basic issues such as the vulnerability of today's ice sheets to near - term global warming and the magnitude of hysteresis effects in ice sheet growth and decay.

The biggest problem seems to be for ice sheet melt, in the discrepancy between the paleoevidence and the models, with models producing rates of melting far below both the paleoevidence and current observations.

To get the big picture right, however, we need models that physically couple ice sheets / shelves with the ocean.

Such solecisms throughout the IPCC's assessment reports (including the insertion, after the scientists had completed their final draft, of a table in which four decimal points had been right - shifted so as to multiply tenfold the observed contribution of ice - sheets and glaciers to sea - level rise), combined with a heavy reliance upon computer models unskilled even in short - term projection, with initial values of key variables unmeasurable and unknown, with advancement of multiple, untestable, non-Popper-falsifiable theories, with a quantitative assignment of unduly high statistical confidence levels to non-quantitative statements that are ineluctably subject to very large uncertainties, and, above all, with the now - prolonged failure of TS to rise as predicted (Figures 1, 2), raise questions about the reliability and hence policy - relevance of the IPCC's central projections.

He is also deeply involved in ice - sheet modeling with specific developments in areas such as ice core dating and temperature reconstruction based on paleothermometry.

Based on ice - sheet model simulations consistent with elevation changes derived from a new Greenland ice core, the Greenland ice sheet very likely contributed between 1.4 m and 4.3 m sea level equivalent, implying with medium confidence a contribution from the Antarctic ice sheet to the global mean sea level during the last interglacial period.

With the use of a climate model of intermediate complexity, we demonstrate that with mwp - 1A originating from the Antarctic Ice Sheet, consistent with recent sea - level fingerprinting inferences, the strength of North Atlantic Deep Water (NADW) formation increases, thereby warming the North Atlantic region and providing an explanation for the onset of the Bølling - Allerød warm interWith the use of a climate model of intermediate complexity, we demonstrate that with mwp - 1A originating from the Antarctic Ice Sheet, consistent with recent sea - level fingerprinting inferences, the strength of North Atlantic Deep Water (NADW) formation increases, thereby warming the North Atlantic region and providing an explanation for the onset of the Bølling - Allerød warm interwith mwp - 1A originating from the Antarctic Ice Sheet, consistent with recent sea - level fingerprinting inferences, the strength of North Atlantic Deep Water (NADW) formation increases, thereby warming the North Atlantic region and providing an explanation for the onset of the Bølling - Allerød warm interwith recent sea - level fingerprinting inferences, the strength of North Atlantic Deep Water (NADW) formation increases, thereby warming the North Atlantic region and providing an explanation for the onset of the Bølling - Allerød warm interval.

Airborne and satellite observations of West Antarctic topography and glacier flow speeds are combined with a computer model simulating ocean - driven glacier melting to show that the ice sheet's collapse is already underway.

Pepijn Bakker and colleagues combine observational records of iceberg - rafted debris with climate models to show that the climate fluctuations seen during the Holocene may have been driven by small variations in the discharge of freshwater from the Antarctic Ice Sheet, amplified through the climate system.