Sentences with phrase «many ice sheet models»
Murali Haran, a professor in the department of statistics at Penn State University; Won Chang, an assistant professor in the department of mathematical sciences at the University of Cincinnati; Klaus Keller, a professor in the department of geosciences and director of sustainable climate risk management at Penn State University; Rob Nicholas, a research associate at Earth and Environmental Systems Institute at Penn State University; and David Pollard, a senior scientist at Earth and Environmental Systems Institute at Penn State University detail how parameters and initial values drive an ice sheet model, whose output describes the behavior of the ice sheet through time.
https://www.sciencedaily.com/
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 larger.
The revised estimate for sea - level rise comes from including new processes in the 3 - dimensional ice sheet model, and testing them against past episodes of high sea - levels and ice retreat.
«It's a major impediment to developing realistic ice sheet models when you don't even know how thick some of these outlet glaciers are,» says Eric Rignot, a remote - sensing glaciologist at the NASA Jet Propulsion Laboratory in Pasadena, California.
The team used the new scheme in five ice sheet models and forced them with climate warming conditions taken from two different climate models.
The results provide insights to guide ongoing development of fully dynamic coupled ice sheet models.
Indeed, many numerical ice sheet models of Greenland assume that a uniform value of geothermal heat flux exists everywhere across Greenland.
«Improving ice sheet models means we need even finer resolution,» Gogineni said.
«Without bed topography you can not build a decent ice sheet model,» said CReSIS director Prasad Gogineni.
Researchers used geologic evidence and ice sheet models to construct a timeline of the Cordilleran's advance and retreat.
«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.
Kuhn, from Germany's Alfred Wegener Institute, added, «This gives confidence in the predictions of the current generation of ice sheet models which are used to forecast future ice loss from Antarctica and resulting sea - level rise.»
A new three - dimensional higher - order thermomechanical ice sheet model: Basic sensitivity, ice stream development, and ice flow across subglacial lakes.
Late Quaternary deglaciation of the Amundsen Sea: Implications for ice sheet modeling.
uncertainty in climate / ocean conditions input into the ice sheet model — any uncertainty in these, both present and future, will feed into uncertainty in the ice sheet model.
The researchers then ran their ice sheet model to simulate how the glaciers responded to global temperature rise under a
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.
What is an ice sheet model?
170 (Symposium on Physical Basis of Ice Sheet Modelling, Vancouver), p. 313 - 322, 1987.
Ice sheet models can be run through many glacial cycles (i.e. cold glacial periods and warm interglacial periods).
In parallel we need significant investment in research on ice sheet models.
In The Physical Basis of Ice Sheet Modelling, pp. 81 - 91.
Inputs needed for a typical Antarctic ice sheet model are the elevation of the bed beneath the ice sheet, air temperature, snowfall and the heat input from the rock below (geothermal heat flux).
Many ice sheet models are now freely available, for example, Elmer, Glimmer - CISM, ISSM, PISM, SICOPLIS, making it possible for a wider community to be able to use these models to answer a wide range of scientific questions.
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.
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.
The researchers then ran their ice sheet model to simulate how the glaciers responded to global temperature rise under a medium - high emissions scenario.
Caption: Visualisation of ice flow in the Antarctic ice sheet model PISM - PIK.
Gallée, H., et al., 1991: Simulation of the last glacial cycle by a coupled, sectorally averaged climate — ice sheet model.
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.
They also speak about sea level sensitivity as being higher than current ice sheet models show.
It seems about 500 ppm CO2 could eventually mean an ice free planet, much lower than the circa 1000 ppm that ice sheet models seem to estimate.
Antarctic ice sheet models double the sea - level rise expected this century if global emissions of heat - trapping pollution remain high.
These simulations were subsequently used as forcing of an ice sheet model.
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.
For example, how much confidence can we really have in results from ice sheet models, which very likely miss important mechanisms (e.g., due to limited understanding of ocean - ice shelf interactions, calving physics and influence of small - scale topography)?
[this is useful, the pre-ice age era, ~ 2.5 — 3.6 million years ago, last time CO2 levels were as high as today] In response to Pliocene climate, ice sheet models consistently produce near - complete deglaciation of the Greenland ice sheet (+7 m) and West Antarctic ice sheet (+4 m) and retreat of the marine margins of the Eastern Antarctic ice sheet (+3 m)(Lunt et al., 2008; Pollard and DeConto, 2009; Hill et al., 2010), altogether corresponding to a global mean sea level rise of up to 14 m.
«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.»
They also speak about sea level sensitivity as being higher than current ice sheet models show.
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.
It seems about 500 ppm CO2 could eventually mean an ice free planet, much lower than the circa 1000 ppm that ice sheet models seem to estimate.
Since we are talking about the models that are being used today to model the next 50 or so years and that those models don't generally include ice sheet models, it is correct to describe ice sheet changes as forcings in this case.
[Response: Indeed it is the latter; most global climate models do not (yet) include continental ice sheet models.
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).
This is despite using observed ice sheet mass loss (0.19 mm / year) in the «modelled» number in this comparison, otherwise the discrepancy would be even larger — the ice sheet models predict that the ice sheets gain mass due to global warming.
But again the «models» estimate includes an observed ice sheet mass loss term of 0.41 mm / year whereas ice sheet models give a mass gain of 0.1 mm / year for this period; considering this, observed rise is again 50 % faster than the best model estimate for this period.
We used an ensemble of ice sheet model runs and plausible Earth models to place bounded constraints on our mass change estimate.
Existing ice sheet models imply that the figure is somewhere between 3 and 16 metres.
An improved Antarctic dataset for high resolution numerical ice sheet models (ALBMAP v1).