Monitoring ice shelves in Antarctica
Ice Shelves are formed when the grounded ice sheet flows out over the ocean, forming a floating platform of ice. Ice shelves in Antarctica are constantly changing due to ice flow causing the ice front to advance, or due to iceberg calving events which cases the ice front to retreat. On this website we have mapped the historical calving front positions on 9 major ice shelves in Antarctica.
Icebergs breaking off ice shelves often form very flat, 'tabular' ice bergs, which are then transported away from the shelf by ocean currents and blowing winds.
In some cases the icebergs are so large that they can become grounded, or stuck on the sea floor beneath the ocean. Iceberg calving is part of the natural cycle of any ice shelf and is not an indicator of ice shelf stability but when whole ice shelves are removed this can trigger the grounded ice behind it to flow more quickly.
On this website we have mapped the historical calving front positions on 9 major ice shelves in Antarctica. Historical calving fronts have been manually delineated from NASA Modis satellite data over the last 10-years, and using the ESA-EU Copernicus Sentinel-1 radar images during the present day.
Two large cracks, Chasm 1 and the ‘Halloween Crack’, are growing on the Brunt Ice Shelf in Antarctica and when they meet, a large iceberg around 3 times the size of Leeds (1,594 km2) will break off.
We use satellite images to measure the growth of both cracks on the Brunt Ice Shelf, along with tracking visible features on the ice shelf surface to measure the ice speed.
Chasm1, located on the West side of the Brunt Ice Shelf, lay dormant for 35 years, but in 2012 it showed signs of movement before starting to propagate across the ice shelf. In 2014 the crack began to grow even more rapidly, and is now over 55 km long! There is now only a 5 km bridge of ice between the tip of Chasm 1 and the McDonald Ice Rumples. When it breaks through, a new iceberg will calve.
A second fracture on the Eastern side of the Brunt Ice Shelf, named the ‘Halloween Crack’ because of its discovery on the 31st October 2016, is growing inland away from the McDonald Ice Rumples. Although the Halloween Crack is more recent, it is now also over 60 km long. Watch the drone footage below to fly along the length of the crack!
Halley Research Station on the Brunt Ice Shelf
The British Antarctic Survey’s (BAS) Halley VI research station was originally located seaward of Chasm 1 on the Brunt Ice Shelf. After the cracks grew rapidly, the whole research base was towed over 23 km inland, safeguarding the buildings and scientific experiments for the future.
In 2015 three 50 km long icebergs were observed close to Brunt by Sentinel-1 during the austral winter. This was a concern because if the icebergs knocked into the fragile floating ice shelf, there was a risk the ice might break putting the station at risk. BAS designed the research base as a series of modules which could be towed to a new location on skis, so the whole station was moved to safety during the 2016/17 season.
Explore the Brunt Ice Shelf for yourself using our interactive map. Zoom in and out to explore the features, and see if you can spot the cracks in the ice!
This map uses images from the Landsat 8 mission.
|Calving Front, 2009-2019||Shapefiles||GeoJSON|
|Chasm 1, 2013-2019||Shapefiles||GeoJSON|
|Halloween Crack, 2016-2019||Shapefiles||GeoJSON|
Ice Speed on the Brunt Ice Shelf
We track moving features, such as crevasses on the ice surface, to measure ice speed every 6-days on the Brunt Ice Shelf!
The European Space Agency's (ESA) Sentinel-1 satellite is a synthetic aperture radar (SAR), which means it can take a picture of the ice surface during the day or night, and it can see through clouds! By extracting velocity measurements along two profiles, crossing Chasm 1 and the Halloween Crack, we can see how ice speed varies on either side of these breaks in the ice.
Take a look at the data yourself, by downloading maps and profiles of ice speed through the CPOM ice velocity data portal. We also distribute frequent maps of ice velocity for other key outlet glaciers on the Antarctic and Greenland ice sheets.
Ice Shelf Calving
Iceberg calving is part of the natural cycle of any ice shelf and is not an indicator of ice shelf stability but when whole ice shelves are removed this can trigger the grounded ice behind it to flow more quickly.
We continuously process Synthetic Aperture Radar (SAR) images from satellites such as Sentinel-1, to measure any change in ice speed after this calving event on the Brunt Ice Shelf.
For a more detailed description on the importance of large ice shelf calving events, take a look at this paper on the Larsen-C iceberg calving event (Hogg and Gudmundsson, 2017) [pdf].
We welcome feedback on our products and the website.
For inquiries of a scientific nature, please contact Dr. Anna Hogg, for inquiries related to web site operations please contact: Alan Muir at email@example.com.