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Interactive climate and ice sheet simulations project substantial East Antarctic ice loss under high emissions, amplified regional sea level rise in the Pacific, and enhanced northern latitude warming despite dampened global mean temperature rise.

If the West Antarctic Ice Sheet (WAIS) melted, sea levels would rise by about 5 m; such changes are thought to have occurred in the past but could not be simulated by models. Pollard and DeConto combine ice-sheet with ice-shelf modelling, and show that over the past 5 million years, the WAIS transitioned among full, intermediate, and collapsed states in only a few thousand years, suggesting possible disintegration of the WAIS if ocean temperatures in the area rise by 5 °C.

Climate and ice-sheet modelling that includes ice fracture dynamics reveals that Antarctica could contribute more than a metre of sea-level rise by 2100 and more than 13 metres by 2500, if greenhouse gas emissions continue unabated.

It is widely accepted that an ice-covered Antarctica first occurred ∼34 million years ago, but the glacial history of the northern hemisphere is less clear. This paper investigates the possibilities of when the continental-scale glaciation of the north occurred with a global climate/ice-sheet model that takes into account the long-term decline of atmospheric CO₂ levels during this period. The CO₂ threshold for glaciation in the north seems to be much lower, and so will have been crossed much later than ∼34 million years ago, suggesting that episodic northern-hemispheric ice sheets have been possible only for the past ∼25 million years.

Orbitally triggered decomposition of soil organic carbon in terrestrial permafrost is suggested as an explanation for a series of sudden and extreme global warming events that occurred about 55 million years ago.

The ~500-metre-thick Prudhoe Dome in northwestern Greenland completely deglaciated 7,000 years ago, highlighting the sensitivity of the ice sheet to mid-Holocene warming, according to luminescence and geochemical data from sub-ice sediments and ice cores.

Rising sea level in the next century exposes the Ports of Los Angeles and Long Beach to higher hazards from Alaskan tsunamis. By 2100, waves generated by an M8 Alaskan earthquake cause similar impacts in California to waves from an Alaskan M9 today.

Geologically validated ice-sheet model reconstructions show large-scale fluctuations between glacial and interglacial periods, suggesting that the Antarctic Ice Sheet is highly sensitive to past and future warm conditions.

Sea level projections are shaped by the tenet that the North American Ice Sheet (NAIS) melted prior to past interglacial sea level peaks. This piece argues that NAIS persisted into past interglacials, which amplifies Antarctic sensitivity to warming.

A long-standing debate regarding the Pliocene history of the East Antarctic Ice Sheet was spurred by the discovery of marine diatoms in the Transantarctic Mountains. Here the authors show that the diatoms were emplaced by wind following a retreat of the ice sheet into coastal basins and subsequent isostatic emergence.

Estimates for sea level three million years ago, a period with similar atmospheric CO₂ levels to today, vary from 10 to 40 m above present. Glacial isostatic adjustment modelling suggests that variations in the height of palaeoshorelines result from the residual adjustment of continental flexure following recent glaciations.

An observationally calibrated ice sheet–shelf model suggests that global warming of 3 °C will trigger rapid Antarctic ice loss, contributing about 0.5 cm per year of sea-level rise by 2100.

Warming of +1.5 °C above pre-industrial levels is too high for the Greenland and Antarctic ice sheets, and even the current climate forcing of +1.2 °C is likely to lead to several meters of sea-level rise, meaning that only a return to +1 °C or lower will avoid extensive loss and damage to coastal populations, according to a synthesis of recent evidence.

The growth of ice on Antarctica about 34 million years ago affected sea level. A combination of modelling and marine sediment analyses shows that sea level near the developing ice sheet first fell and then rose as a result of crustal deformation imposed by the ice growth.

Plough marks in Pine Island Bay, West Antarctica, left by the keels of drifting icebergs 12,000 years ago provide evidence that marine ice-cliff instability can drive rapid ice-sheet retreat.

The East Antarctic ice sheet retreated at the end of the last glacial period. Terrestrial and marine data suggest that the retreat began 14,000 years ago, indicating that the East Antarctic ice sheet probably did not contribute to meltwater pulse 1a 14,700 years ago.

Ice sheet freshwater discharge interacts with the climate and affects the ice sheet’s sensitivity to climate change. This study shows that the overall feedback shifts from positive to negative as the pace of future warming intensifies

Studies of an Antarctic marine sediment core suggest that the East Antarctic Ice Sheet retreated in the vicinity of the Wilkes Subglacial Basin during extended warm periods of the late Pleistocene, when temperatures were similar to those predicted to occur within this century.

About 5.6 million years ago the Mediterranean Sea evaporated leaving a 1.5 km deep basin while at the same time Antarctica’s ice sheet grew. Here the authors show that growth of Antarctic ice lowered sea-level, which cut off the Atlantic Ocean from the Mediterranean Sea and allowed it to evaporate.

The East Antarctic ice sheet was larger than present during past cold periods. Seafloor geophysical data show that in the Ross Sea, the extended ice sheet was underlain by an active hydrologic system during the glacial termination.

Ice grounding features discovered in the Arctic Basin, in water depths exceeding 1 km and dated to the penultimate glacial, suggest a past Arctic ice shelf. Here, the authors undertake numerical simulations that shed light on how such an ice shelf could have formed, its dynamics and most likely configuration.

The different contributions of long-term and short-term variability to the evolution of ice sheets lead to substantial uncertainties in ice sheet models. This Review describes the response of ice sheets to oceanic, atmospheric and hydrological processes across a range of timescales.

Climate change will increase meltwater and iceberg discharge from Antarctica, with implications for future climate and sea levels. Iceberg melt will partly offset greenhouse warming in the Southern Ocean and dampen the positive feedback loop between ice-sheet melting and subsurface warming.

Considering cryosphere and warming uncertainties together implies drastically increased risk of threshold crossing in the cryosphere, even under lower-emission pathways, and underscores the need to halve emissions by 2030 in line with the 1.5 °C limit of the Paris Agreement.

A synthesis of intervals of rapid climatic change evident in the geological record reveals some of the Earth system processes and tipping points that could lead to similar events in the future.