Focus

Warming ice sheets

Focus
August 2011 Volume 4 No 8 pp493-571

Future sea-level rise is uncertain, not least because it is unclear how, and how fast, the ice sheets in Greenland and Antarctica are going to respond to ocean and atmosphere warming. This collection of research papers, overview articles and opinion pieces highlights current understanding of the sensitivity of the planet's cryosphere to temperature rise, including a view back into the past and far into the future.

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Editorial

Ice and ocean p493

doi:10.1038/ngeo1232

A substantial amount of the Earth's surface water moves between ice sheets and oceans as the climate oscillates on geological timescales. Ocean warming, as well as atmospheric temperature rise, affects the current redistribution in response to climate change.

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Review

Stability of the West Antarctic ice sheet in a warming world pp506 - 513

Ian Joughin & Richard B. Alley

doi:10.1038/ngeo1194

Ice sheets, and in particular the West Antarctic ice sheet, are expected to shrink in size as the world warms, which in turn will raise sea level. A Review of the literature suggests that much of this ice sheet will survive beyond this century, but confident estimates of the likelihood of future collapse require further work.

Abstract | Full text | PDF (1,398KB)

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Letters

Different magnitudes of projected subsurface ocean warming around Greenland and Antarctica pp524 - 528

Jianjun Yin, Jonathan T. Overpeck, Stephen M. Griffies, Aixue Hu, Joellen L. Russell & Ronald J. Stouffer

doi:10.1038/ngeo1189

Accurate projections of global sea-level rise require information of future ocean warming in the vicinity of the large ice sheets. An analysis of 19 climate model projections suggests that subsurface ocean warming near both polar ice sheets will be substantial, with the potential to lead to significant increases in ice-mass loss.

First paragraph | Full text | PDF (8,897KB)

Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf pp519 - 523

Stanley S. Jacobs, Adrian Jenkins, Claudia F. Giulivi & Pierre Dutrieux

doi:10.1038/ngeo1188

The ice shelf buttressing Antarctica's Pine Island Glacier has been melting rapidly. Observations taken between 1994 and 2009 show that meltwater production has increased by about 50% since 1994, as a result of a stronger circulation below the ice shelf.

First paragraph | Full text | PDF (2,605KB)

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From the archives

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Article

Winter warming in West Antarctica caused by central tropical Pacific warming

Qinghua Ding, Eric J. Steig, David S. Battisti & Marcel Küttel

doi:10.1038/ngeo1129

The Pacific sector of Antarctica has experienced substantial warming in the past 30 years. Observations of global surface temperatures and atmospheric circulation data show that the warming in continental West Antarctica is linked to sea surface temperature changes in the tropical Pacific Ocean.

Abstract | Full text | PDF (1,201KB)

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Letters

Ongoing climate change following a complete cessation of carbon dioxide emissions

Nathan P. Gillett, Vivek K. Arora, Kirsten Zickfeld, Shawn J. Marshall & William J. Merryfield

doi:10.1038/ngeo1047

Following a hypothesized complete cessation of carbon dioxide emissions, global climate models simulate approximately constant global mean temperatures for centuries. Long-term simulations with the Canadian Earth System Model suggest that, on these timescales, regional changes in temperature and precipitation are nevertheless significant, and that Southern Ocean warming at intermediate depths could affect the stability of Antarctic ice.

First paragraph | Full text | PDF (1,108KB)

Regionally differentiated contribution of mountain glaciers and ice caps to future sea-level rise

Valentina Radić & Regine Hock

doi:10.1038/ngeo1052

The contribution to sea-level rise from mountain glaciers and ice caps has grown over the past decades. A projection of their melting during the twenty-first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21% of their total global volume.

First paragraph | Full text | PDF (395KB)

Sea level as a stabilizing factor for marine-ice-sheet grounding lines

Natalya Gomez, Jerry X. Mitrovica, Peter Huybers & Peter U. Clark

doi:10.1038/ngeo1012

Climate change could potentially destabilize marine ice sheets such as the West Antarctic ice sheet. A suite of predictions of sea-level change following grounding-line migration suggests that the gravitational effects of melting on local sea levels can exert a stabilizing influence on marine ice sheets on a reverse slope.

First paragraph | Full text | PDF (569KB)

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Article

Simultaneous estimation of global present-day water transport and glacial isostatic adjustment

Xiaoping Wu, Michael B. Heflin, Hugo Schotman, Bert L. A. Vermeersen, Danan Dong, Richard S. Gross, Erik R. Ivins, Angelyn W. Moore & Susan E. Owen

doi:10.1038/ngeo938

Present-day changes in the thickness of ice sheets and glacial isostatic adjustment both affect space geodetic measurements. A combination of gravity measurements and geodetic data of surface movement with a data-assimilating model of ocean bottom pressure allows the simultaneous estimation of present-day water transport and glacial isostatic adjustment.

First paragraph | Full text | PDF (1,574KB)

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Letter

Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat

Adrian Jenkins, Pierre Dutrieux, Stanley S. Jacobs, Stephen D. McPhail, James R. Perrett, Andrew T. Webb & David White

doi:10.1038/ngeo890

Thinning ice in West Antarctica is currently contributing about 10% of the observed rise in global sea level. Observations obtained from an autonomous underwater vehicle operating beneath Pine Island Glacier, West Antarctica, reveal that the glacier was recently grounded on a transverse ridge in the sea floor, but now warm sea water flows through the widening gap above the ridge.

First paragraph | Full text | PDF (7,079KB)

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News and Views

Glaciology: Sliding to sea

Byron R. Parizek

doi:10.1038/ngeo879

Greenland's ice sheet does not look like an alpine glacier. However, it behaves like one in the way its meltwater lubricates basal motion, suggesting that projections of sea-level change will require unified knowledge of basal processes in glaciers and ice sheets.

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Letters

Accelerated Antarctic ice loss from satellite gravity measurements

J. L. Chen, C. R. Wilson, D. Blankenship & B. D. Tapley

doi:10.1038/ngeo694

Accurate quantification of Antarctic ice-sheet mass balance and its contribution to global sea-level rise remains challenging. Gravity Recovery and Climate Experiment data spanning the period April 2002 to January 2009 confirm earlier estimates of ice loss for Antarctica and indicate that East Antarctica started losing mass in about 2006.

First paragraph | Full text | PDF (893KB)

Large-scale changes in Greenland outlet glacier dynamics triggered at the terminus

Faezeh M. Nick, Andreas Vieli, Ian M. Howat & Ian Joughin

doi:10.1038/ngeo394

The recent, dramatic retreat of many outlet glaciers of the Greenland ice sheet has raised concerns over Greenland's contribution to future sea-level rise. Simulations with a numerical ice-flow model indicate that the recent rates of mass loss in Greenland's outlet glaciers are transient and should not be extrapolated into the future.

First paragraph | Full text | PDF (997KB)

Acceleration of Jakobshavn Isbræ triggered by warm subsurface ocean waters

David M. Holland, Robert H. Thomas, Brad de Young, Mads H. Ribergaard & Bjarne Lyberth

doi:10.1038/ngeo316

Observations over past decades show a sudden switch of Jakobshavn Isbræ — a large outlet glacier feeding a deep-ocean fjord on Greenland's west coast — from slow thickening to rapid thinning in 1997. This switch is associated with a doubling in glacier velocity. Hydrographic data show a concurrent sudden increase in subsurface ocean temperatures along the entire west coast of Greenland, suggesting that the changes in Jakobshavn Isbræ were triggered by the arrival of relatively warm water originating from the Irminger Sea.

First paragraph | Full text | PDF (814KB)

Recent Antarctic ice mass loss from radar interferometry and regional climate modelling

Eric Rignot, Jonathan L. Bamber, Michiel R. van den Broeke, Curt Davis, Yonghong Li, Willem Jan van de Berg & Erik van Meijgaard

doi:10.1038/ngeo102

Observed estimates of ice losses in Antarctica combined with regional modelling of ice accumulation in the interior suggest that East Antarctica is close to a balanced mass budget, but large losses of ice occur in the narrow outlet channels of West Antarctic glaciers and at the northern tip of the Antarctic Peninsula.

First paragraph | Full text | PDF (983KB)

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