CR
Cryospheric Sciences

ice-ocean interactions

Image of the Week – Receiving messages from the deep

March 10, 2023
Image of the Week – Receiving messages from the deep
‘Walter’ eyes us up as he takes a breather in one of our ocean access holes. [Natalie Robinson | NIWA]

The Weddell Seal pops his head up through the hole in the floor of the shipping container… for the fourth time today. The shipping container is one of several making up our field camp on sea ice, 40 km from Scott Base – situated on Ross Island, in the south-western Ross Sea. Today I talk about the sub-ice platelet layer, which provides the base for a rich marine environment. Generating super ...[Read More]

The fragile connection of the Ocean and the Cryosphere – a story from the past

March 24, 2022
The fragile connection of the Ocean and the Cryosphere – a story from the past
The primordial Earth. [Credit: Simone Marchi/SwRI]

Compared to the formation and evolution of the Earth’s surface, the ancient oceans receive little attention in geological history. However, understanding the rise and fall of the oceans of the past—or “ghost oceans”—can reveal crucial information about the evolution of our planet, the cryosphere included. Can oceans play a historical role in climate change? If water bodies had not existed, would w ...[Read More]

The “Cliffs Notes” on Ice-Cliff Failure

May 6, 2021
The “Cliffs Notes” on Ice-Cliff Failure
An ice cliff above the ocean adjacent to Thwaites Glacier in West Antarctica. Credits: NASA Public domain, via Wikimedia Commons.

The retreat of large glaciers that drain the Greenland and Antarctic ice sheets could expose immense ice-cliffs at newly-bared calving faces, which are the exposed ends of glaciers where, in these cases, glacier ice meets the ocean. Past a certain height, these ice cliffs will become susceptible to collapsing from high stresses, a process known as structural ice-cliff failure. If a taller ice clif ...[Read More]

Did you know… about the fluctuating past of north-east Greenland?

November 8, 2019
Did you know… about the fluctuating past of north-east Greenland?
Fig. 1: Map of the north-east sector of Greenland showing the location of the North East Greenland Ice Stream (NEGIS) with its three outlet glaciers (Nioghalvfjerdsfjorden (79N), Zachariae Isstrøm (ZI) and Storstrømmen Glacier (SG)), and the offshore bathymetry and the position of its margin reconstructed for the Last Glacial Maximum (LGM) (dotted black line) [Credit: Ilaria Tabone].

Recent geological data shows that during a very cold phase of our Earth’s climate (between 40,000 and 26,000 years ago), there was a huge expansion of polar ice sheets, yet the north-eastern part of the Greenland ice sheet was less extensive than today. How could this have occurred? In this post we shed light on the potential causes of this ice sheet behaviour. What do we know about present- ...[Read More]

Image of the Week – How geometry limits thinning in the interior of the Greenland Ice Sheet

May 26, 2017
Image of the Week – How geometry limits thinning in the interior of the Greenland Ice Sheet
Figure 1: (a) Mass change of the Greenland ice sheet measured by NASA’s GRACE mission in cm/yr water equivalent from January 2003 to December 2013 [Credit: modified from Velicogna et al., 2014]. (b) Dynamic surface elevation change and mass loss along the margin of West Greenland as measured by DEM differencing. The map shows surface elevation change from 1985 to present for 16 outlet glaciers. Circles represent mass change (estimated using 917 kg m-3 as ice density) with circle areas proportional to magnitude of mass change. [Credit: Denis Felikson]

The Greenland ice sheet flows from the interior out to the margins, forming fast flowing, channelized rivers of ice that end in fjords along the coast. Glaciologists call these “outlet glaciers” and a large portion of the mass loss from the Greenland ice sheet is occurring because of changes to these glaciers. The end of the glacier that sits in the fjord is exposed to warm ocean water that can me ...[Read More]