Mass balance of the antarctic ice sheet from 1992 to 2017. A glacier is the product of how much mass it receives and how much it loses by melting. State of antarctic and greenland ice sheet mass balance. Imbie greenland and antarctic datasets european environment. Ice sheet massbalance estimates for greenland and antarctica. Owing to gravitational forces, the melting of the antarctic ice sheet contributes more to sea level rise in the northern hemisphere than the melting of the greenland ice sheet. A cubic kilometer of ice weighs approximately one metric gigaton. Mass flux measurements across the margin of the antarctic. Abstract 1245788simons this award supports a project to undertake an accurate and robust spatial and temporal assessment of the mass flux in the antarctic region from the data collected by the grace satellites. It covers about 98% of the antarctic continent and is the largest single mass of ice on earth. Imbie is a collaboration between scientists supported by the european space agency and the national aeronautics and space administration, and contributes to assessment reports. Marshall 3 1centre for polar observation and modelling, university college london, gower street, london wc1e 6bt, uk 2centre for polar observation and modelling, scott polar research institute, university of cambridge, lens. Icesat2 will measure changes in the antarctic ice sheet within the thickness of a no. An introduction to glacier mass balance antarctic glaciers.
The antarctic ice sheet is the largest single mass of ice on earth. What is the surface mass balance of the antarctic ice sheet. Yet putting all of the terms together to form an accurate estimate of the mass balance of the greenland and antarctic ice sheets has proven complicated. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008. Ar4 was considerably more candid than ar5 about the continuing impact of the end of the last ice age.
The antarctic ice sheet is one of the two polar ice caps of the earth. Mass flux measurements across the margin of the antarctic ice sheet metadata record for data from asac project 2318 see the link below for public details on this project. Mass balance of the antarctic ice sheet article pdf available in philosophical transactions of the royal society a mathematical physical and engineering sciences 3641844. Satellite images reveal huge cracks in antarctic ice sheet. We use 26 estimates of ice sheet mass balance derived from satellite. Ice sheet modeling of greenland, antarctica helps predict. The antarctic ice sheet is an important indicator of climate change and driver of sealevel rise. Two estimates from radar altimeter measurements of. The goals of ismass are to promote the research on the estimation of the mass balance of ice sheets and its contribution to sea level, to facilitate the coordination. We evaluate the state of the mass balance of the antarctic ice sheet over the last four decades using a comprehensive, precise satellite record and output products from a regional atmospheric climate model to document its impact on sealevel rise. Measurements of ice thickness, temperature profiles, largescale deformation, and other sea ice characteristics were made.
The mass loss is dominated by enhanced glacier flow in areas closest to warm, salty, subsurface circumpolar deep water, including east antarctica. The mass of the antarctic ice sheet has changed over the last several years. To predict how the ice sheets mass balance might change in the future, scientists must understand the current mass balance of the antarctic ice sheet, along with the factors that influence it. Numerical modeling of the antarctic ice sheet has gone through a paradigm shift over the last decade. Antarctic ice sheet surface mass balance antarctic glaciers. An unweighted average of recent estimates suggests that antarctica moved from a weakly negative mass balance in the 1990s to a faster rate of mass loss at a rate of between 45 and 120 gigatonnes. Mass balance of the greenland ice sheet from 1992 to 2018 nature.
Overview and assessment of antarctic icesheet mass balance estimates. Mass balance of the antarctic ice sheet from 1992 to 2017 request. It covers an area of almost 14 million square kilometres 5. The greenland and antarctic ice sheets will make a dominant contribution to 21st century sealevel rise if current climate trends continue. The imbie team has published time series of the mass balance of the greenland and antarctic ice sheets. Observing and modeling ice sheet surface mass balance lenaerts. Progress in numerical modeling of antarctic icesheet. Ice losses from antarctica have tripled since 2012, according to a comprehensive survey by scientists from all over the world. Highresolution mass trends of the antarctic ice sheet. That net gain slowed to 82 billion tons of ice per. Several drilling programs have used a multiparameter approach for assessment. It will contribute to solving the problem of antarcticas mass balance by providing a longterm record of elevation changes. However, predicting the expected loss of ice sheet mass.
State of antarctic and greenland ice sheet mass balance and icesheet modeling richard b. Spatial and temporal antarctic ice sheet mass trends. An increased rate of mass loss results in a faster rise in the global mean sea level. This not only required substantial software development, including allowing for. Changes in ice dynamics and mass balance of the antarctic. Consequently these products will be produced by the cci antarctic ice sheet project over the next three years. The observation program was carried out in the fall of 2007 and the spring of 2009 during a drift program of the nathaniel b. The potential for collapse of the antarctic ice sheet remains the largest single source of uncertainty in projections of future sealevel rise. The mass balance of a glacier is a measure of its health, reflecting the balance between the amount of snow that accumulates on the glaciers. The sum of the changes from all basins, figure 2a, is an antarctic total mass variation time series from january 2003 to december 20. Antarctic ice sheet mass gains greater than losses. We use 26 estimates of ice sheet mass balance derived from satellite altimetry. Antarctic ice sheet mass loss has increased eurekalert. Using a mathematical technique from statistical physics and large ensembles of stateoftheart ice sheet.
The east antarctic ice sheet has grown slightly over the period shown. Request pdf mass balance of the antarctic ice sheet from 1992 to 2017 the antarctic ice sheet is an important indicator of climate change and driver of sealevel rise. Ice sheet mass balance from remote sensing measurements. Increases in ice loss from the glaciers of antarctica, greenland, and the rest of the arctic are contributing to sea level rise, while similarly dramatic changes are occurring in the sea ice cover of the arctic and southern oceans. We evaluate the state of the mass balance of the antarctic ice sheet over the. Using a technique developed during work on the greenland ice sheet, the work will significantly improve on prior ice mass estimates made from public global level 2 grace data. According to the new analysis of satellite data, the antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001.
Mass gains of antarctic ice sheet greater than losses. Highresolution modelling of antarctic ice sheet smb. Palmer icebreaker along with a buoy network established on the antarctic sea ice. C transect was performed and elaborated using the gipsyoasis ii software 56. The antarctic ice sheet is an important indicator of climate change and. Mass balance, ice velocity, surface elevation change and grounding lines were determined to be the most important data products. This chain of events illustrated the vulnerability of ice shelves to climate warming and their buffering role on the mass balance of antarctica. Overview and assessment of antarctic icesheet mass. Pronounced regional warming in the antarctic peninsula triggered ice shelf collapse, which led to a 10fold increase in glacier flow and rapid ice sheet retreat.
While initially models focussed on longtime diffusive response to surface mass balance changes, processes occurring at the marine boundary of the ice sheet are progressively incorporated in newly developed stateoftheart icesheet models. Supraglacial lakes are important to ice sheet mass balance because their development and drainage has been linked to changes in ice flow velocity. This uncertainty comes from an imperfect understanding of ice sheet processes and the internal variability of climate forcing of ice sheets. Ice thickness and more in sea ice mass balance in the. There is variation between regions within antarctica as can be seen in figure 2. Still, areas of the continent, like the antarctic peninsula photographed above, have increased their mass loss in the last decades. Introduction 2 assessment of antarctic mass balance is an essential element in understanding past and present changes in global mean sea level and climate, and in understanding present variations in the global hydrological cycle, ocean temperature, salinity, ocean general circulation, atmospheric dynamics, and other problems. Research ice sheets and climate university of colorado boulder.
Greenland and antarctic ice sheets european environment. This is a significant, but small, proportion of the total antarctic ice loss determined by grace see figures in john cooks summary above. Greenland than it is for antarctica, reflecting differences in ice sheet size. Launched january 12, 2003, nasas ice, cloud, and land elevation satellite, or icesat, is designed to measure the mass balance of earths ice sheets balance between processes that add ice to the ice sheets versus processes that remove ice, the height of clouds and aerosols, and the topography of the land. She is also responsible for integration and testing of the issm glacier energy and mass balance gemb surface module that simulates the evolution of the ice sheet surface radiation balance and firn densification. The ice sheet mass balance intercomparison exercise imbie is a. Widespread distribution of supraglacial lakes around the. There are around 7 metres of potential sealevel rise locked up in the greenland icesheets and 57 metres in the antarctic icesheets. The ice sheet mass balance intercomparison exercise imbie was established in 2011 as a community effort to reconcile satellite measurements of ice sheet mass balance. Four decades of antarctic ice sheet mass balance from 19792017. Recent advances in the determination of the mass balance of polar ice sheets show that the greenland ice sheet is losing mass by nearcoastal thinning, and that the west antarctic ice sheet, with thickening in the west and thinning in the north, is probably thinning overall. The mass imbalance of the east antarctic ice sheet is likely to be small, but even its sign cannot yet be determined. Surprising facts about the antarctic ice sheet seeker.
Here are some facts about the planets single biggest ice mass, and why it is so important to the planet. It covers an area of almost 14 million square km and contains 30 million cubic km. A new nasa study says that antarctica is overall accumulating ice. New images taken by the esas copernicus sentinel satellites shows two major new cracks in the west antarctic ice sheet. Public summary from project this project is a cooperative venture between australian and italian institutes in a study of the mass budget of a large sector of the. Assessment of the data and techniques suggests overall antarctic ice sheet mass balance ranging from growth of 50 gt yr1 to shrinkage of 200 gt yr1 from 1993 to 2003. Surface mass balance contributions to acceleration of. Map showing the rates of mass changes from icesat 20032008 over antarctica. Research based on observations from nasas twin nasagerman aerospace centers twin gravity recovery and climate experiment grace satellites indicates that between 2002 and 2016, antarctica shed approximately 125 gigatons of ice per year, causing global sea level to rise by 0. This article is published with open access at abstract mass balance estimates for the antarctic ice sheet ais in the 2007 report by. Four decades of antarctic ice sheet mass balance from 1979.
The 300 gtyear range is approximately 15% of the annual mass input and 0. Best of all, quantarctica is free to download and redistribute. Mass losses of the antarctic ice sheet have increased global sea level by 7. The antarctic ice sheet is the largest reservoir of nonoceanic water mass. Research ice sheets and climate university of colorado. The expert group on ice sheet mass balance and sea level ismass is cosponsored by the scientific committee on antarctic research, the international arctic science committee iasc, and the wcrp climate and cryosphere project. The mass balance of a glacier is a concept critical to all theories of glacier flow and behaviour. The west antarctic ice sheet and the antarctic peninsula ice sheet are losing a lot of ice mass, at an overall increasing rate. Mass balance of the antarctic ice sheet from 1992 to 2017 nature. The data are somewhat challenging to ingest into standard software packages, but. Here we combine satellite observations of its changing volume, flow and gravitational attraction. Quantarctica is a collection of antarctic geographical datasets which works with the free, crossplatform, opensource software qgis.
824 355 391 370 1401 1209 493 592 690 1404 226 347 645 1155 293 1555 1208 13 1271 1149 812 32 504 1242 531 1263 1142 807 1124 275 866 1445 1296 1183 1387 958 525 91 1288 1376 929 118 777