The Earth’s polar ice sheets contain the equivalent of about 65 metres of sea level rise, and they are losing mass. Meltwater runoff, glacier retreat and ice shelf collapse have been observed in Greenland, West Antarctica, and the Antarctic Peninsula, and evidence of ice shelf thinning in East Antarctica is also emerging.
Understanding the sensitivity of the polar ice sheets to anthropogenic warming remains a major research challenge. In order to constrain future projections of ice sheet variability and the ensuing effects on the global climate system, we must better understand internal ice sheet variability, the interaction between ice sheets, the ocean, the atmosphere and the solid Earth, and improve our knowledge of ice sheet behaviour during past periods of climate change.
This collection has been curated by the Earth science editorial team with the intention of providing the ice sheets research community with a visible and discoverable home at Nature Communications. It is our hope that this continually updated collection of comments, reviews and research articles will provide a useful resource for researchers and decision makers alike and help bridge the Arctic and Antarctic communities.
Understudied in the Antarctic system are the subsurface interfaces between ice-sheet, ocean and geological substrate. Here, the authors review our understanding of these components and propose new avenues of holistic dynamic modeling to achieve a unified understanding of past, present and future polar climate.
The evolution of the Antarctic Ice Sheet is driven by a combination of climate forcing and non-climatic feedbacks. In this review, the authors focus on feedbacks between the Antarctic Ice Sheet and the solid Earth, and the role of these feedbacks in shaping the response of the ice sheet to past and future climate changes.
Non-linear response of summertime marine productivity to increased meltwater discharge around Greenland
Discharge from Greenland is known to deliver nutrients to the marine environment. Here, the authors show that the majority of the nutrients fueling summertime productivity downstream of Greenland’s glaciers seemingly originate from entrainment in subglacial discharge plumes rather than from meltwater itself.
Across all glaciers, ice caps, and ice sheets, the gravitational driving stress, and therefore the average basal shear stress falls in a narrow range that tops out around 1 bar. Here, the authors show that the mechanical resistance posed by heterogeneous infiltration of ice into sediments governs the peak bed strength.
Low frequency intrinsic ocean variability has an unknown impact on Antarctic ice shelves, yet can arise even in the absence of varying climate forcing. Here, the authors show that this variability significantly affects modelled basal melting under the Totten Ice Shelf, with implications for the attribution of change.
Ice sheet models forced by climate model output indicate ice-sheet retreat during the Pliocene, yet concerns remain regarding potential model bias. Here, the authors present results from the Pliocene Ice-sheet Modelling Intercomparison Project, and show that results are highly dependent on the model forcing used.
The Greenland Ice Sheet has increasingly lost mass over the past few decades, yet the contribution from glaciers in Northeast Greenland is difficult to quantify. Here, the authors show that the floating part of 79 North Glacier has continuously lost mass since at least 2001, with a very high annual variability.
The West Antarctic Ice Sheet sits atop an extensional rift system with volcano-like features, yet we do not know if any of these volcanoes are active, because identifying subglacial volcanism remains a challenge. Here, the authors find evidence in helium isotopes that a large volcanic heat source is emanating from beneath the fast-melting Pine Island Ice Glacier.
Submarine glacial landforms are used to reconstruct the Holocene retreat dynamics and stability of Petermann Glacier in northwest Greenland. Here, a large grounding-zone wedge at the mouth of Petermann fjord indicates a period of glacier stability, with final retreat likely driven by marine ice cliff instability.
The outlet glaciers that comprise the Northeast Greenland Ice Stream (NEGIS) have experienced accelerated retreat in recent years, yet their longterm stability remains unclear. Here, via cosmogenic surface exposure and radiocarbon ages, the authors investigate the stability of the NEGIS for the past 45 kyr.
Numerical simulations of a kilometre-thick Arctic ice shelf consistent with ice grounding observations
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.
Warm Atlantic water circulates cyclonically around the Nordic Seas while gradually cooling. Here, the authors show that the retreat of the ice edge toward Greenland has led to further transformation of this water mass, which is no longer situated underneath sea ice when transiting the western Iceland Sea in winter.
Evidence for ephemeral middle Eocene to early Oligocene Greenland glacial ice and pan-Arctic sea ice
With rapidly disappearing ice, understanding the past behavior of the cryosphere is critical. Here, the authors indicate the initiation and disappearance of glaciation on Greenland and Arctic sea ice coincided in the past, synchronous with Antarctic ice and global ice volume, and a CO2 threshold of ~500 p.p.m.v.
The surface types that comprise the dark zone of the Greenland Ice Sheet, an area of bare ice with low albedo, are unknown. Here, the authors use UAV imagery to show that, during the melt-season, biologically active surface impurities are responsible for spatial albedo patterns and the dark zone itself.
Lakes on the Greenland Ice Sheet transfer water to the bed when they drain, but the impact is unknown. Here, the authors use a 3D model to show that lakes drain when fractures form, causing a chain reaction in which cascading lake drainages extend inland and deliver water to previously isolated regions of the bed.
Ocean heat is important in forcing ice sheet retreat, yet past ocean temperature data from proximal ice sheet locations are sparse. Here, the authors present temperature reconstructions from the Wilkes Land subglacial basin during the mid-Miocene, and show that warm waters sustained ice sheet retreat 17–14.8 Ma.