Melting Of Ice Sheets Research Articles

Cloud microphysics and circulation anomalies control differences in future Greenland melt

Recently, the Greenland Ice Sheet (GrIS) has become the main source of barystatic sea-level rise1,2. The increase in the GrIS melt is linked to anticyclonic circulation anomalies, a reduction in cloud cover and enhanced warm-air advection3–7. The Climate Model Intercomparison Project fifth phase (CMIP5) General Circulation Models (GCMs) do not capture recent circulation dynamics; therefore, regional climate models (RCMs) driven by GCMs still show significant uncertainties in future GrIS sea-level contribution, even within one emission scenario5,8–10. Here, we use the RCM Modele Atmospherique Regional to show that the modelled cloud water phase is the main source of disagreement among future GrIS melt projections. We show that, in the current climate, anticyclonic circulation results in more melting than under a neutral-circulation regime. However, we find that the GrIS longwave cloud radiative effect is extremely sensitive to the modelled cloud liquid-water path, which explains melt anomalies of +378 Gt yr–1 (+1.04 mm yr–1 global sea level equivalent) in a +2 °C-warmer climate with a neutral-circulation regime (equivalent to 21% more melt than under anticyclonic circulation). The discrepancies between modelled cloud properties within a high-emission scenario introduce larger uncertainties in projected melt volumes than the difference in melt between low- and high-emission scenarios11. Greenland Ice Sheet melt is contributing to sea-level rise; however, uncertainties exist about its future contributions. A regional climate model shows that clouds are the primary cause of this uncertainty, with melt varying significantly depending on the cloud water phase and atmospheric circulation.

Rethinking Tasmania’s Regionality from an Antarctic Perspective: Flipping the Map

Tasmania hangs from the map of Australia like a drop in freefall from the substance of the mainland. Often the whole state is mislaid from Australian maps and logos (Reddit). Tasmania has, at least since federation, been considered peripheral—a region seen as isolated, a ‘problem’ economically, politically, and culturally. However, Tasmania not only cleaves to the ‘north island’ of Australia but is also subject to the gravitational pull of an even greater land mass—Antarctica. In this article, we upturn the political conventions of map-making that place both Antarctica and Tasmania in obscure positions at the base of the globe. We show how a changing global climate re-frames Antarctica and the Southern Ocean as key drivers of worldwide environmental shifts. The liquid and solid water between Tasmania and Antarctica is revealed not as a homogenous barrier, but as a dynamic and relational medium linking the Tasmanian archipelago with Antarctica. When Antarctica becomes the focus, the script is flipped: Tasmania is no longer on the edge, but core to a network of gateways into the southern land. The state’s capital of Hobart can from this perspective be understood as an "Antarctic city", central to the geopolitics, economy, and culture of the frozen continent (Salazar et al.). Viewed from the south, we argue, Tasmania is not a problem, but an opportunity for a form of ecological, cultural, economic, and political sustainability that opens up the southern continent to science, discovery, and imagination.

North Atlantic and sub-Antarctic Ocean temperatures: possible onset of a transient stadial cooling stage

The ice core glacial-interglacial record of the last 450 kyr (Cortese et al. Paleogeogr Paleoclimatol 22:4, 2007), development of cold ice meltwater regions at fringes of the Greenland and the West Antarctic ice sheets, and climate projections by Hansen et al. (Atmos Chem Phys 16:3761–3812, 2016), support a relation between ice sheet melting and the cooling of neighboring ocean zones by ice meltwater. Several factors lead to cooling of parts of the North Atlantic Ocean and adjacent lands, including the following: (A) a slowdown of the Atlantic meridional overturning circulation (AMOC); (B) flow of cold ice meltwater from the Greenland ice sheet into the North Atlantic Ocean; (C) undulation and weakening of the jet stream at the Arctic boundary due to a rise in temperature in the Arctic circle at twice the rate of warming at lower latitudes and the ice-water albedo flip. Penetration of Arctic-derived cold air masses southward through a weakened jet stream boundary ensues in extreme weather events in North America and Europe. The slowdown of the AMOC (Caesar et al. Nature 556:191–196, 2018; Praetorius Nat Clim Chang 5:475–480, 2018; Thornalley et al. Nature 556:227–230, 2018; Smeed et al. Geophys Res Lett 45(3):1527–1533, 2018) and growing cold ocean region (Rahmstorf et al. Nat Clim Chang 5:475–480, 2015) may herald the onset of a stadial event. A large-scale stadial event, possibly on the scale of the 8.3–8.2 kyr-old Laurentian melt event, or even the 12.9–11.7-kyr-old Younger Dryas stadial (Carlson Encycl Quat Sci 3:126–134, 2013), could ensue from advanced melting of both the Greenland ice sheet and the Antarctic ice sheet. A stadial would be succeeded by the resumption of warming driven by a continuing rise in greenhouse gas concentrations and amplifying feedback effects. These projections need to be examined vis-a-vis the continuous linear IPCC temperature rise models.

Compensating Biases and a Noteworthy Success in the CMIP5 Representation of Antarctic Sea Ice Processes

AbstractCoupled Model Intercomparison Project phase 5 (CMIP5) climate models simulate a wide range of historical sea ice areas. Even models with areas close to observed values may contain compensating errors, affecting reliability of their projections. This study focuses on the seasonal cycle of sea ice, including analysis of model concentration budgets. Many models have insufficient autumn ice growth, leading to large winter biases. A subset of models accurately represent sea ice evolution year‐round. However, comparing their winter ice concentration budget to observations reveals a range of behaviors. At least one model has an accurate ice budget, which is only possible due to realistic ice drifts. The CMIP5 generation of model physics and resolution is therefore structurally capable of accurately representing processes in Antarctic sea ice. This implies that substantially improved projections of Antarctic dense ocean water formation and ice sheet melting are possible with appropriate subsetting of existing climate models.

Glacier Algae: A Dark Past and a Darker Future.

“Glacier algae” grow on melting glacier and ice sheet surfaces across the cryosphere, causing the ice to absorb more solar energy and consequently melt faster, while also turning over carbon and nutrients. This makes glacier algal assemblages, which are typically dominated by just three main species, a potentially important yet under-researched component of the global biosphere, carbon, and water cycles. This review synthesizes current knowledge on glacier algae phylogenetics, physiology, and ecology. We discuss their significance for the evolution of early land plants and highlight their impacts on the physical and chemical supraglacial environment including their role as drivers of positive feedbacks to climate warming, thereby demonstrating their influence on Earth’s past and future. Four complementary research priorities are identified, which will facilitate broad advances in glacier algae research, including establishment of reliable culture collections, sequencing of glacier algae genomes, development of diagnostic biosignatures for remote sensing, and improved predictive modeling of glacier algae biological-albedo effects.

An Attempt to Observe Vertical Land Motion along the Norwegian Coast by CryoSat-2 and Tide Gauges

Present-day climate-change-related ice-melting induces elastic glacial isostatic adjustment (GIA) effects, while paleo-GIA effects describe the ongoing viscous response to the melting of late-Pleistocene ice sheets. The unloading initiated an uplift of the crust close to the centers of former ice sheets. Today, vertical land motion (VLM) rates in Fennoscandia reach values up to around 10 mm/year and are dominated by GIA. Uplift signals from GIA can be computed by solving the sea-level equation (SLE), 
 
 
 
 S
 ˙
 
 
 
 = 
 
 
 
 N
 ˙
 
 
 
 − 
 
 
 
 U
 ˙
 
 
 
 . All three quantities can also be determined from geodetic observations: relative sea-level variations (
 
 
 
 S
 ˙
 
 
 
 ) are observed by means of tide gauges, while rates of absolute sea-level change (
 
 
 
 N
 ˙
 
 
 
 ) can be observed by satellite altimetry; rates of VLM (
 
 
 
 U
 ˙
 
 
 
 ) can be determined by GPS (Global Positioning System). Based on the SLE, 
 
 
 
 U
 ˙
 
 
 
 can be derived by combining sea-surface measurements from satellite altimetry and relative sea-level records from tide gauges. In the present study, we have combined 7.5 years of CryoSat-2 satellite altimetry and tide-gauge data to estimate linear VLM rates at 20 tide gauges along the Norwegian coast. Thereby, we made use of monthly averaged tide-gauge data from PSMSL (Permanent Service for Mean Sea Level) and a high-frequency tide-gauge data set with 10-min sampling rate from NMA (Norwegian Mapping Authority). To validate our VLM estimates, we have compared them with the independent semi-empirical land-uplift model NKG2016LU_abs for the Nordic-Baltic region, which is based on GPS, levelling, and geodynamical modeling. Estimated VLM rates from 1 Hz CryoSat-2 and high-frequency tide-gauge data reflect well the amplitude of coastal VLM as provided by NKG2016LU_abs. We find a coastal average of 2.4 mm/year (average over all tide gauges), while NKG2016LU_abs suggests 2.8 mm/year; the spatial correlation is 0.58.

The Blake Geomagnetic Field Event recorded in a sequence of marine and continental facies outcropping in the coast of Buenos Aires province, Argentina

Different authors have suggested that there is a relationship between Quaternary geomagnetic field events and climate variability. Considering that in a recent paper a detailed stratigraphic study in a section of the coast of Claromecó (Buenos Aires province) indicates Late Pleistocene paleoclimatic changes, a paleomagnetic study was performed in the same stratigraphic succession. The analyzed sedimentary section belongs to “Belgranense” unit that is composed of continental and marine deposits. According to previously published dates and stable isotope results presented in this paper, it is proposed that 6 facies (sedimentary units) of the Claromecó section developed during the interglacial Marine Isotope Stage 5 (MIS 5). These units are presumably coeval with one of the best known geomagnetic field events, the Blake Event, occurred during the MIS 5, between ca. 120 and ca. 115 ka. The studied units from the base to the top are: 1) diagenetic wackestones with clasts of sand, 2) pedogenized loessian deposits, 3) lower marine wackestones, 4) lower tidal channel deposits, 5) upper marine wackestones and 6) upper tidal channel deposits. The section is capped by a continental gravity flow much younger than MIS 5. Different facies record distinct characteristic remanent magnetizations (ChRM) suggesting that these have a not modern origin. Low-field thermomagnetic curves and hysteresis loops were performed for all the sedimentary facies that provide magnetic remanences. Special sediment magnetism experiments were made for the units with reverse and/or oblique reverse components including isothermal remanent magnetization and anhysteretic remanent magnetization to perform the Lowrie-Fuller test. In these units opaque minerals were identified using polished and thin sections together with scanning electron microscopy analysis. According to all the results it is interpreted that the Blake Geomagnetic Field Event was recorded in the pedogenized loessian deposits with magnetite crystals generated during pedogenetic processes, and in extracellular biogenic magnetite crystals in the lower marine wackestones. The reverse and/or oblique reverse ChRM components were recorded before the lower tidal channel deposits, which have normal polarity directions. The Blake Geomagnetic Field Event was recorded in Claromecó during last interglacial MIS 5, however a direct correlation cannot be made between the recorded transitional polarity and a marine transgression corresponding to an important melting of ice sheets during this marine isotope stage. The magnetic components recorded in the studied sequence could be used as a stratigraphic tool to help identify “Belgranense” unit in Argentina or correlative sedimentary facies outcropping in South America.

Sand from Greenland’s Melting Ice Sheet Could Bring in Business

The effects of climate change could fuel a new sand mining industry in Greenland.

Assessment of coastal vulnerability in Chabahar Bay due to climate change scenarios

Summary A substantial body of research has shown that two key factors of global sea level rise are thermal expansion and melting of land-based ice, glaciers and ice sheets. Moreover, climate change may result in changes to wind speeds and directions, consequently resulting in contributions to variations in wind-wave components, wave heights and directions. In this research, climate change scenarios were used to assess the coastal vulnerability to the Chabahar port area due to global sea level rise, significant wave height changes and tidal regime effects. These three items were calculated separately using numerical models and the impacts of possible climate change scenarios were applied to estimate possible changes to these items by 2100. Significant wave heights for 25, 50 and 100-year return periods were evaluated. Based on statistical analysis, the maximum significant wave heights for the A2 and A1B scenarios were estimated at approximately 13.7 and 7.6, respectively. Since the main aim of this research was to assess the coastal zones at higher flood risk, therefore the mean global sea level rise, extreme values of significant wave heights and tidal heights were investigated. The height of sea during sea storms and for the most extreme case was calculated as 17.3 m and 11.2 m for A2 and the A1B scenarios, respectively. According to output maps of inundation areas, large coastal zones in the Chabahar port area are at risk due to the sea storms and possible climate change.

Atmospheric Dynamics Footprint on the January 2016 Ice Sheet Melting in West Antarctica

AbstractIn January of 2016, the Ross Sea sector of the West Antarctica ice sheet experienced a 3‐week‐long melting episode. Here we quantify the association of the large‐extent and long‐lasting melting event with the enhancement of the downward longwave (LW) radiative fluxes at surface due to water vapor, cloud, and atmospheric dynamic feedbacks using the ERA‐Interim data set. The abnormally long‐lasting temporal surges of atmospheric moisture, warm air, and low‐level clouds increase the downward LW radiative energy flux at the surface during the massive ice‐melting period. The concurrent timing and spatial overlap between poleward wind anomalies and positive downward LW radiative surface energy flux anomalies over West Antarctica due to warmer air temperature and increases in atmospheric water vapor and cloud coverage provide direct evidence that warm and moist air advection from lower latitudes to West Antarctica causes the rapid long‐lasting warming and vast ice mass loss in January of 2016.

Global environmental consequences of twenty-first-century ice-sheet melt.

Government policies currently commit us to surface warming of three to four degrees Celsius above pre-industrial levels by 2100, which will lead to enhanced ice-sheet melt. Ice-sheet discharge was not explicitly included in Coupled Model Intercomparison Project phase 5, so effects on climate from this melt are not currently captured in the simulations most commonly used to inform governmental policy. Here we show, using simulations of the Greenland and Antarctic ice sheets constrained by satellite-based measurements of recent changes in ice mass, that increasing meltwater from Greenland will lead to substantial slowing of the Atlantic overturning circulation, and that meltwater from Antarctica will trap warm water below the sea surface, creating a positive feedback that increases Antarctic ice loss. In our simulations, future ice-sheet melt enhances global temperature variability and contributes up to 25 centimetres to sea level by 2100. However, uncertainties in the way in which future changes in ice dynamics are modelled remain, underlining the need for continued observations and comprehensive multi-model assessments.

Promises and perils of sand exploitation in Greenland

Ice flow dynamics of the Greenland ice sheet control the production of sediment. Future acceleration in glacial flow and ice sheet melt will amplify Greenland’s supply of sediment to the coastal zone. Globally, sand and gravel reserves are rapidly depleting while the demand is increasing, largely due to urban expansion, infrastructural improvements and the enhancement of coastal protection in response to climate change. Here, we show that an abundance of sand and gravel provides an opportunity for Greenland to become a global exporter of aggregates and relieve the increasing global demand. The changing Arctic conditions help pave a sustainable way for the country towards economic independence. This way, Greenland could benefit from the challenges brought by climate change. Such exploitation of sand requires careful assessment of the environmental impact and must be implemented in collaboration with the Greenlandic society. Sand and gravel have become important commodities due to infrastructure and coastal protection schemes, leading to shortages on a global level. This Perspective looks at how Greenland could diversify its economy towards export of its sand resources and the potential impacts on the environment and local way of life.

Holocene Indian Ocean sea level, Antarctic melting history and past Tsunami deposits inferred using sea level reconstructions from the Sri Lankan, Southeastern Indian and Maldivian coasts

Holocene sea level change in the northern Indian Ocean was studied using geochemical and geophysical approaches. Molluscs were sub-sampled for radiocarbon dating from sediment cores retrieved from a south Sri Lankan coastal lagoon. They were then combined with previously published sediment core radiocarbon ages from the same lagoon. We observe a ∼20-fold reduction in sedimentation rates at around 4 ka, attributed to a decrease in the rate of sea level rise. Previously reported radiocarbon ages based on total organic matter in the lagoon show remarkable agreement with our new dates suggesting stable and homogeneous sedimentation during the last 8 ka. Comparison of down core age trends of both data sets reveal that sediments are older than coeval molluscs, except for the horizons adjacent to the paleo Tsunami layers, indicating fresh and younger sediments are provided during Tsunami events, which could become a new proxy for identifying paleo Tsunamis. Compilation of previously reported sea level indicators from Sri Lanka, Southeastern India and the Maldives, together with predicted sea level obtained from a glacio-hydro-isostatic adjustment model (GIA), suggest that 3–4 m of global sea level equivalent ice sheet melting occurred during the Mid Holocene due to the retreat of the Antarctic and/or Greenland ice sheets. Previous works suggests late Holocene (ca. 4 ka) climate anomalies in both the low and high latitudes. We suggest the low latitude climate anomaly, transmitted via atmosphere to the high latitude during the late Holocene, seems to have induced changes in polar ice sheets.

Upper Sun River Drainage Basin Origin Determined by Topographic Map Interpretation Techniques: Lewis and Clark and Teton Counties, Montana, USA

A new and fundamentally different regional geomorphology paradigm in which massive south- and southeast-oriented meltwater floods flowed across the entire Missouri River drainage basin is tested by interpreting detailed topographic maps of the Montana upper Sun River drainage basin region by trying to explain origins of previously unexplained or poorly explained erosional landforms located upstream from Sun River Canyon (which cuts across Montana’s north-to-south oriented Sawtooth Range). Mountain passes, through valleys, and other drainage divide low points along what are today high mountain ridges, including the North American east-west continental divide, are interpreted to be evidence of drainage routes that once crossed the region. These drainage divide crossings suggest that prior to erosion of present-day upper Sun River drainage basin valleys, massive floods moved in south directions across what are today the north-oriented Middle and South Fork Flathead River drainage basins into today’s upper Sun River drainage basin area and carved a complex of diverging and converging channels into what was probably a low relief surface now represented by the crests of the region’s highest mountain ridges. Further, the map evidence shows how a diverging complex of south- and southeast-oriented upstream Sun River drainage basin flood flow channels changed flow direction to cross the Sawtooth Range in a northeast direction before converging on the Montana plains at a location downstream from Sun River Canyon. The observed upper Sun River drainage basin area topographic map evidence is consistent with the new geomorphology paradigm predictions, in which massive south-oriented meltwater floods flowing across the rising rim of a continental ice sheet created deep “hole” (created by deep ice sheet erosion and ice sheet weight caused crustal warping) are diverted to flow in northeast and north directions into and across deep “hole” space being opened up by ice sheet melting.

Use of Topographic Map Evidence to Test a Recently Proposed Regional Geomorphology Paradigm: Wind River-Sweetwater River Drainage Divide Area, Central Wyoming, USA

Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continental ice sheet melt water floods that flowed across the entire Missouri River drainage basin. The new paradigm forces recognition of an ice sheet created and occupied deep “hole” and is fundamentally different from the commonly accepted paradigm in which a pre-glacial north- and northeast-oriented slope would have prevented continental ice sheet melt water from reaching or crossing the Wind River-Sweetwater River drainage divide. Divide crossings (or low points) are identified as places where water once flowed across the drainage divide. Map evidence is interpreted first from the accepted paradigm perspective and second from the new paradigm perspective to determine the simplest explanation. Both paradigm perspectives suggest south-oriented water crossed the drainage divide, although accepted paradigm interpretations do not satisfactorily explain the large number of observed divide crossings and are complicated by the need to bury the Owl Creek and Bridger Mountains to explain why the Wind River now flows in a north direction through Wind River Canyon. New paradigm interpretations explain the large number of divide crossings as diverging and converging channel evidence (as in flood-formed anastomosing channel complexes), Owl Creek and Bridger Mountain uplift to have occurred as south-oriented floodwaters carved Wind River Canyon, and a major flood flow reversal (caused by ice sheet related crustal warping and the opening up of deep “hole” space by ice sheet melting) as being responsible for the Wind River abrupt turn to the north. While this test only addresses topographic map evidence, Occam’s Razor suggests the new paradigm offers what in science should be the preferred Wind River-Sweetwater River drainage divide origin interpretations.

Use of Stream and Dismembered Stream Valleys Now Crossing Wyoming’s Northern Laramie Mountains to Test a Recently Proposed Regional Geomorphology Paradigm, USA

Detailed topographic maps show multiple stream valleys and what are probably dismembered stream valleys that extend completely across Wyoming’s northern Laramie Mountains. Several of the most obvious valleys are described with valley origins first explained (or attempted to be explained) from the commonly accepted regional geomorphology paradigm (accepted paradigm) perspective and second from a recently proposed regional geomorphology paradigm (new paradigm) perspective in an effort to determine which of the two paradigms provides the simplest explanations. Accepted paradigm explanations require at least some of the valley erosion to have occurred prior to deposition of Oligocene and Miocene sediments that once covered the northern Laramie Mountains (with some of the exhumed valleys now containing sediment cover remnants). In contrast the fundamentally different new paradigm requires immense south-oriented continental ice sheet melt water floods to have crossed the region as ice sheet related crustal warping raised the region and the Laramie Mountains (and implies sediments now partially filling some of the valleys are probably flood deposited materials). The new paradigm provides simpler explanations for the origins of the valleys now extending completely across the northern Laramie Mountains and also for their related barbed tributaries, truncated side valleys, and drainage route U-turns than the accepted paradigm, although the new paradigm also leads to a fundamentally different middle and late Cenozoic regional geologic history than is currently recognized. One paradigm cannot be used to judge a different paradigm, but the paradigms can be compared based on their ability to explain evidence and Occam’s Razor can determine which of the two paradigms provides the simplest explanations. New paradigm explanations for northern Laramie Mountains valley origins investigated here require fewer assumptions than the accepted paradigm explanations suggesting the new paradigm merits serious future consideration.

GEOCENTRIC MEAN SEA LEVEL FIELDS AT THE GERMAN NORTH SEA AND BALTIC COAST

Global mean sea level has risen over the 20th century (Hay et al. 2015; Dangendorf et al. 2017) and under sustained greenhouse gas emissions it is projected to further accelerate throughout the 21st century (Church et al. 2013) with large spatial variations, significantly threatening coastal communities. Locally the effects of geocentric (sometimes also referred to absolute) sea level rise can further be amplified by vertical land motion (VLM) due to natural adjustments of the solid earth to the melting of the large ice-sheets during the last deglaciation (GIA) or local anthropogenic interventions such as groundwater or gas withdrawal (e.g. Santamaría-Gómez et al. 2017). Both, the observed and projected geocentric sea level rise as well as VLM are critically important for coastal planning and engineering, since only their combined effect determines the total threat of coastal flooding at specific locations. Furthermore, due large spatial variability of sea level, information is required not only at isolated tide gauge (TG) locations but also along the coastline stretches in between.

Wintertime Fjord‐Shelf Interaction and Ice Sheet Melting in Southeast Greenland

AbstractA realistic numerical model was constructed to simulate the oceanic conditions and circulation in a large southeast Greenland fjord (Kangerdlugssuaq) and the adjacent shelf sea region during winter 2007–2008. The major outlet glaciers in this region recently destabilized, contributing to sea level rise and ocean freshening, with increased oceanic heating a probable trigger. It is not apparent a priori whether the fjord dynamics will be influenced by rotational effects, as the fjord width is comparable to the internal Rossby radius. The modeled currents, however, describe a highly three‐dimensional system, where rotational effects are of order‐one importance. Along‐shelf wind events drive a rapid baroclinic exchange, mediated by coastally trapped waves, which propagate from the shelf to the glacier terminus along the right‐hand boundary of the fjord. The terminus was regularly exposed to around 0.5 TW of heating over the winter season. Wave energy dissipation provoked vertical mixing, generating a buoyancy flux which strengthened overturning. The coastally trapped waves also acted to strengthen the cyclonic mean flow via Stokes' drift. Although the outgoing wave was less energetic and located at the opposite sidewall, the fjord did exhibit a resonant response, suggesting that fjords of this scale can also exhibit two‐dimensional dynamics. Long periods of moderate wind stress greatly enhanced the cross‐shelf delivery of heat toward the fjord, in comparison to stronger events over short intervals. This suggests that the timescale over which the shelf wind field varies is a key parameter in dictating wintertime heat delivery from the ocean to the ice sheet.

Staging the Speculative

Staging the Speculative

Interactive ocean bathymetry and coastlines for simulating the last deglaciation with the Max Planck Institute Earth System Model (MPI-ESM-v1.2)

Abstract. As ice sheets grow or decay, the net flux of freshwater into the ocean changes and the bedrock adjusts due to isostatic adjustments, leading to variations in the bottom topography and the oceanic boundaries. This process was particularly intense during the last deglaciation due to the high rates of ice-sheet melting. It is, therefore, necessary to consider transient ocean bathymetry and coastlines when attempting to simulate the last deglaciation with Earth system models (ESMs). However, in most standard ESMs the land-sea mask is fixed throughout simulations because the generation of a new ocean model bathymetry implies several levels of manual corrections, a procedure that is hardly doable very often for long runs. This is one of the main technical problems towards simulating a complete glacial cycle with general circulation models. For the first time, we present a tool allowing for an automatic computation of bathymetry and land-sea mask changes in the Max Planck Institute Earth System Model (MPI-ESM). The algorithms developed in this paper can easily be adapted to any free-surface ocean model that uses the Arakawa-C grid in the horizontal and z-grid in the vertical including partial bottom cells. The strategy applied is described in detail and the algorithms are tested in a long-term simulation demonstrating the reliable behaviour. Our approach guarantees the conservation of mass and tracers at global and regional scales; that is, changes in a single grid point are only propagated regionally. The procedures presented here are an important contribution to the development of a fully coupled ice sheet–solid Earth–climate model system with time-varying topography and will allow for transient simulations of the last deglaciation considering interactive bathymetry and land-sea mask.