scholarly journals Ice Sheets and Sea-Level Rise in Earth System Models

2014 ◽  
Author(s):  
Stephen Price
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Earth System ◽  
System Models ◽  
Earth System Models ◽  
And Sea Level

scholarly journals A kinematic formalism for tracking ice–ocean mass exchange on the Earth's surface and estimating sea-level change

2020 ◽  
Vol 14 (9) ◽  
pp. 2819-2833
Author(s):  
Surendra Adhikari ◽  
Erik R. Ivins ◽  
Eric Larour ◽  
Lambert Caron ◽  
Helene Seroussi
Keyword(s):  
Solid Earth ◽  
Sea Level ◽  
Mass Exchange ◽  
Ice Sheets ◽  
Earth System ◽  
Generic Level ◽  
Ocean Mass ◽  
Geophysical Processes ◽  
Ice Sheet Dynamics ◽  
And Sea Level

Abstract. Polar ice sheets are important components of the Earth system. As the geometries of land, ocean and ice sheets evolve, they must be consistently captured within the lexicon of geodesy. Understanding the interplay between the processes such as ice-sheet dynamics, solid-Earth deformation, and sea-level adjustment requires both geodetically consistent and mass-conserving descriptions of evolving land and ocean domains, grounded ice sheets and floating ice shelves, and their respective interfaces. Here we present mathematical descriptions of a generic level set that can be used to track both the grounding lines and coastlines, in light of ice–ocean mass exchange and complex feedbacks from the solid Earth and sea level. We next present a unified method to accurately compute the sea-level contribution of evolving ice sheets based on the change in ice thickness, bedrock elevation and mean sea level caused by any geophysical processes. Our formalism can be applied to arbitrary geometries and at all timescales. While it can be used for applications with modeling, observations and the combination of two, it is best suited for Earth system models, comprising ice sheets, solid Earth and sea level, that seek to conserve mass.

scholarly journals ISSM-SESAW v1.0: mesh-based computation of gravitationally consistent sea-level and geodetic signatures caused by cryosphere and climate driven mass change

2016 ◽  
Vol 9 (3) ◽  
pp. 1087-1109 ◽  
Author(s):  
Surendra Adhikari ◽  
Erik R. Ivins ◽  
Eric Larour
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Computational Cost ◽  
Wave Number ◽  
Time Varying ◽  
Earth System ◽  
Viscous Effects ◽  
Legendre Series ◽  
System Models ◽  
Earth System Models

Abstract. A classical Green's function approach for computing gravitationally consistent sea-level variations associated with mass redistribution on the earth's surface employed in contemporary sea-level models naturally suits the spectral methods for numerical evaluation. The capability of these methods to resolve high wave number features such as small glaciers is limited by the need for large numbers of pixels and high-degree (associated Legendre) series truncation. Incorporating a spectral model into (components of) earth system models that generally operate on a mesh system also requires repetitive forward and inverse transforms. In order to overcome these limitations, we present a method that functions efficiently on an unstructured mesh, thus capturing the physics operating at kilometer scale yet capable of simulating geophysical observables that are inherently of global scale with minimal computational cost. The goal of the current version of this model is to provide high-resolution solid-earth, gravitational, sea-level and rotational responses for earth system models operating in the domain of the earth's outer fluid envelope on timescales less than about 1 century when viscous effects can largely be ignored over most of the globe. The model has numerous important geophysical applications. For example, we compute time-varying computations of global geodetic and sea-level signatures associated with recent ice-sheet changes that are derived from space gravimetry observations. We also demonstrate the capability of our model to simultaneously resolve kilometer-scale sources of the earth's time-varying surface mass transport, derived from high-resolution modeling of polar ice sheets, and predict the corresponding local and global geodetic signatures.

scholarly journals Change in mass balance of polar ice sheets and sea level from high-resolution GCM simulations of greenhouse warming

2000 ◽  
Vol 30 ◽  
pp. 197-203 ◽  
Author(s):  
Martin Wild ◽  
Atsumu Ohmura
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheets ◽  
General Circulation Models ◽  
Dominant Factor ◽  
Greenhouse Warming ◽  
Sea Level Changes ◽  
And Sea Level

AbstractFor projecting future sea level, the mass-balance changes on Greenland and Antarctica are considered to be crucial. Promising tools for such estimates are general circulation models (GCM). Until recently, a major impediment was their coarse grid resolution (3°-6°) causing substantial uncertainties in the mass-balance calculations of the poorly resolved ice sheets. The present study is based on a new climate-change experiment of the highest resolution currently feasible (1.1 °) performed with the ECHAM4 T106 GCM, thereby increasing confidence in the projected mass-balance and sea-level changes. This new experiment, with doubled CO2 concentration, suggests that the mass gain in Antarctica due to increased accumulation exceeds the melt-induced mass loss in Greenland by a factor of three. The resulting mass-balance change on both ice sheets is equivalent to a net sea-level decrease of 0.6 mm a"1 under doubled CO2 conditions. This may compensate for a significant portion of the melt-induced sea-level rise from the smaller glaciers and ice caps, thus leaving thermal expansion as the dominant factor for sea-level rise over the next decades. This compensating effect, however, no longer applies should atmospheric CO2 concentration reach levels well above "doubled the present value". On the contrary, under these conditions, the greenhouse warming would become large enough to induce substantial melting also on the Antarctic ice sheet, thereby significantly accelerating global sea-level rise.

scholarly journals Icy Interactions

Eos ◽  
2018 ◽  
Vol 99 ◽  
Author(s):  
Jeremy Fyke ◽  
Olga Sergienko ◽  
Marcus L�fverstr�m ◽  
Stephen Price ◽  
Jan Lenaerts
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Earth System ◽  
Complex Interactions ◽  
The Earth

Complex interactions between ice sheets and other components of the Earth system determine how ice sheets contribute to sea level rise.

scholarly journals ISSM-SLPS: geodetically compliant Sea-Level Projection System for the Ice-sheet and Sea-level System Model v4.17

2020 ◽  
Vol 13 (10) ◽  
pp. 4925-4941
Author(s):  
Eric Larour ◽  
Lambert Caron ◽  
Mathieu Morlighem ◽  
Surendra Adhikari ◽  
Thomas Frederikse ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ocean Circulation ◽  
Ice Sheets ◽  
Ice Sheet ◽  
System Model ◽  
Level System ◽  
Projection System ◽  
Forward Models ◽  
And Sea Level

Abstract. Understanding future impacts of sea-level rise at the local level is important for mitigating its effects. In particular, quantifying the range of sea-level rise outcomes in a probabilistic way enables coastal planners to better adapt strategies, depending on cost, timing and risk tolerance. For a time horizon of 100 years, frameworks have been developed that provide such projections by relying on sea-level fingerprints where contributions from different processes are sampled at each individual time step and summed up to create probability distributions of sea-level rise for each desired location. While advantageous, this method does not readily allow for including new physics developed in forward models of each component. For example, couplings and feedbacks between ice sheets, ocean circulation and solid-Earth uplift cannot easily be represented in such frameworks. Indeed, the main impediment to inclusion of more forward model physics in probabilistic sea-level frameworks is the availability of dynamically computed sea-level fingerprints that can be directly linked to local mass changes. Here, we demonstrate such an approach within the Ice-sheet and Sea-level System Model (ISSM), where we develop a probabilistic framework that can readily be coupled to forward process models such as those for ice sheets, glacial isostatic adjustment, hydrology and ocean circulation, among others. Through large-scale uncertainty quantification, we demonstrate how this approach enables inclusion of incremental improvements in all forward models and provides fidelity to time-correlated processes. The projection system may readily process input and output quantities that are geodetically consistent with space and terrestrial measurement systems. The approach can also account for numerous improvements in our understanding of sea-level processes.

The Inevitable One

2021 ◽  
pp. 228-248
Author(s):  
Eelco J. Rohling
Keyword(s):  
Thermal Expansion ◽  
Global Warming ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Ocean Warming ◽  
Global Mean Temperature ◽  
To Come ◽  
Global Mean ◽  
And Sea Level

This chapter considers processes we cannot reverse, at least in the short term: it is already too late. These are processes related to slow responses or feedbacks in the climate system, including ocean warming and sea-level rise, and they will continue to drive change whatever we do. As explained in the chapter, ocean warming operates on timescales of centuries and resulting changes in Earth’s major ice sheets take many centuries to millennia. Sea-level rise is caused by thermal expansion due to ocean warming and by reduction in the volume of land-based ice, due to global warming. Because of the timescales involved, the oceans will keep warming for centuries, dragging global mean temperature along with them, and sea level will also rise for many centuries to come. The chapter reviews the impacts of these processes, whose inevitability means that humanity has no choice but to adapt to them.

scholarly journals Layered seawater intrusion and melt under grounded ice

2021 ◽  
Author(s):  
Alexander A. Robel ◽  
Earle Wilson ◽  
Helene Seroussi
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Seawater Intrusion ◽  
Ice Sheets ◽  
Ice Sheet ◽  
System Model ◽  
Glacier Terminus ◽  
Grounding Line ◽  
Flow Through ◽  
And Sea Level

Abstract. Increasing melt of ice sheets at their floating or vertical interface with the ocean is a major driver of marine ice sheet retreat and sea level rise. However, the extent to which warm, salty seawater may drive melting under the grounded portions of ice sheets is still not well understood. Previous work has explored the possibility that dense seawater intrudes beneath relatively light subglacial freshwater discharge, similar to the salt wedge observed in many estuarine systems. In this study, we develop a generalized theory of layered seawater intrusion under grounded ice, including where subglacial hydrology occurs as a macroporous water sheet over impermeable beds or as microporous Darcy flow through permeable till. Using predictions from this theory, we show that seawater intrusion over hard beds may feasibly occur up to tens of kilometers upstream of a glacier terminus or grounding line. On the other hand, seawater is unlikely to intrude more than tens of meters through subglacial till. High-resolution simulations using the Ice-Sheet and Sea-Level System Model (ISSM) show that even just a few hundred meters of basal melt caused by seawater intrusion upstream of marine ice sheet grounding lines can cause projections of marine ice sheet volume loss to be 10–50 % higher or 100 % higher for kilometers of intrusion-induced basal melt. These results suggest that further observational, experimental and numerical investigations are needed to determine whether the conditions under which extensive seawater intrusion occurs and whether it will indeed drive rapid marine ice sheet retreat and sea level rise in the future.

A kinematic formalism for tracking ice-ocean mass exchange on the Earth's surface and estimating sea-level change 

2021 ◽  
Author(s):  
Surendra Adhikari ◽  
Erik Ivins ◽  
Eric Larour ◽  
Lambert Caron ◽  
Helene Seroussi
Keyword(s):  
Solid Earth ◽  
Sea Level ◽  
Mass Exchange ◽  
Ice Sheets ◽  
Earth System ◽  
Generic Level ◽  
California Institute Of Technology ◽  
Ocean Mass ◽  
Institute Of Technology ◽  
And Sea Level

<p>Polar ice sheets are important components of the Earth System.  As the geometries of land, ocean, and ice sheets evolve, they must be consistently captured within the lexicon of geodesy.  Understanding the interplay between the processes such as ice-sheet dynamics, solid-Earth deformation, and sea-level adjustment requires both geodetically consistent and mass conserving descriptions of evolving land and ocean domains, grounded ice sheets and floating ice shelves, and their respective interfaces. Here we present mathematical descriptions of a generic level set that can be used to track both the grounding lines and coastlines, in light of ice-ocean mass exchange and complex feedbacks from the solid Earth and sea level. We next present a unified method to accurately compute the sea-level contribution of evolving ice sheets based on the change in ice thickness, bedrock elevation and mean sea level caused by any geophysical processes. Our formalism can be applied to arbitrary geometries and at all time scales. While it can be used for applications with modeling, observations and the combination of two, it is best suited for Earth System models, comprising ice sheets, solid Earth and sea level, that seek to conserve mass.</p><p>© 2020 California Institute of Technology. Government sponsorship is acknowledged.</p>

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