Accelerating glacier volume loss on Juneau Icefield driven by hypsometry and melt-accelerating feedbacks.

Globally, glaciers and icefields contribute significantly to sea level rise. Here we show that ice loss from Juneau Icefield, a plateau icefield in Alaska, accelerated after 2005 AD. Rates of area shrinkage were 5 times faster from 2015-2019 than from 1979-1990.

60 million years of glaciation in the Transantarctic Mountains.

The Antarctic continent reached its current polar location ~83 Ma and became shrouded by ice sheets ~34 Ma, coincident with dramatic global cooling at the Eocene-Oligocene boundary. However, it is not known whether the first Antarctic glaciers formed immediately prior to this or were present significantly earlier. Here we show that mountain glaciers were likely present in the Transantarctic Mountains during the Late Palaeocene (~60-56 Ma) and middle Eocene (~48-40 Ma).

Rapid accelerations of Antarctic Peninsula outlet glaciers driven by surface melt.

Atmospheric warming is increasing surface melting across the Antarctic Peninsula, with unknown impacts upon glacier dynamics at the ice-bed interface. Using high-resolution satellite-derived ice velocity data, optical satellite imagery and regional climate modelling, we show that drainage of surface meltwater to the bed of outlet glaciers on the Antarctic Peninsula occurs and triggers rapid ice flow accelerations (up to 100% greater than the annual mean). This provides a mechanism for this sector of the Antarctic Ice Sheet to respond rapidly to atmospheric warming.

Corrigendum: Widespread movement of meltwater onto and across Antarctic ice shelves.

This corrects the article DOI: 10.1038/nature22049.

Widespread movement of meltwater onto and across Antarctic ice shelves.

Surface meltwater drains across ice sheets, forming melt ponds that can trigger ice-shelf collapse, acceleration of grounded ice flow and increased sea-level rise. Numerical models of the Antarctic Ice Sheet that incorporate meltwater's impact on ice shelves, but ignore the movement of water across the ice surface, predict a metre of global sea-level rise this century in response to atmospheric warming. To understand the impact of water moving across the ice surface a broad quantification of surface meltwater and its drainage is needed.

Ice stream motion facilitated by a shallow-deforming and accreting bed.

Ice streams drain large portions of ice sheets and play a fundamental role in governing their response to atmospheric and oceanic forcing, with implications for sea-level change. The mechanisms that generate ice stream flow remain elusive. Basal sliding and/or bed deformation have been hypothesized, but ice stream beds are largely inaccessible.