Shackleton's Endurance: Where Could the Floe Go?

By Stephanie Pfirman

A new simulation tool lets viewers follow sea ice movements.

August 3, 2022

The Long View Physics Cartography

Record breaking low Antarctic sea ice cover led to the finding of the Endurance shipwreck in March 2022, amazingly well preserved on the sea floor since it was crushed by the ice and sunk on November 21, 1915.

Ad Right

Following this catastrophe, Sir Ernest Shackleton—the expedition leader—led his 27-man crew on an extraordinary journey of survival, first navigating three lifeboats to Elephant Island, then on with a total crew of six on a 1,300 kilometer boat journey to South Georgia. Once there, they had to cross a mountain chain before finally reaching the Grytviken whaling village on the other side of the island. Shackleton eventually managed to rescue all of his crew who had been forced to live on Elephant Island while he sought help, one of the truly heroic expeditions of all time.

Analysis of potential alternative trajectories—given what we know about ice conditions since 1979—shows that although Shackleton was both lucky and unlucky with the environmental conditions, he and his crew only survived through amazing feats of perseverance, as well as navigational and operational skill.

But the low ice conditions that allowed for the wreck of the Endurance to be located in 2022 are in contrast with the recent ice conditions of 2019 and 2020, which could have delivered not just the crew, but also the intact Endurance, to within about 831 kilometers of Grytviken.

You can explore this recent drift yourself—as well as other alternatives from 1980 to 2020—using the new version of the Ice Tracker referenced in Going with the Floe (November–December 2009). SITU: Sea Ice Tracking Utility, developed in collaboration with Garrett Campbell, Bruno Tremblay, Bob Newton, Walt Meier, Chuck Fowler, and Patricia DeRepentigny, allows you to track past sea ice trajectories in the Antarctic as well as both past and future trajectories in the Arctic.

Image courtesy of the authors; opening image Frank Hurley (1885-1962) / National Library of Australia Hurley negative collection.

To explore the conditions where Endurance was stuck drifting along with the sea ice and eventually sank, visit the SITU website and follow the instructions below.
Click "How to Use" to learn the functionality.
Then select "Obs South" to shift the tool from the Arctic to the Antarctic
To Plot Drift Trajectory for an expedition freezing in 2019
Select a base map "concentration"—this will show sea-ice concentration
In Timeline Settings
Start Date Yr "2019" Mo "1"
End Date Yr "2020" Mo "12"—This will show drift of the ice starting in January, the month the crew reported no longer being able to maneuver the ship
In Start of Track
Latitude: 76.56
Longitude: 328.6—this corresponds to the location where the Endurance was frozen into the ice (76°34'S 31°30'W)
In Output Type select "Ice Tracks"
In Loop Controls select "step month" and in
Include in loop: click "track" and "map"
and then click the play arrow—this will play an animation showing the potential trajectory of Endurance drifting with the sea ice, in parallel with the changing ice conditions during the drift.

Above is a plot of sea ice concentration over time. It is made by selecting “Plot all Parameters” on the right side of SITU. From the plot, sea ice concentration along this drift trajectory didn’t drop below 50 percent until November 2020. At this point the ship would likely have been released from the ice if it hadn’t been crushed already.

To Plot Conditions at Endurance's Sinking Location
In Timeline Settings
Start Date Yr "1980" Mo "1"
End Date Yr "2020" Mo "12"—This will show conditions at Endurance’s sinking location over the entire 40 year data set from 1980 to 2020
In Start of Track
Latitude: 68.65
Longitude: 307.56—this corresponds to the location where the Endurance was crushed and sank (68°39'30"S 52°26'30"W)
In Output Type select "Fixed Point"

The plots above show over the past 40 years that the average sea ice concentration at this location was 65 percent and the average ice age was 1.4 years. We calculate the age of the ice age in order to estimate its thickness. Older ice is generally thicker and more ridged than younger ice, and so poses more of a crushing hazard to ships. The plots show that there were only three times when there would have been less than 50 percent sea ice cover in the vicinity of the ship, in austral summer 1993, 1999, and 2002 (November–March). Furthermore, 77 percent of the time, there was greater than 90 percent ice cover at this location and 90 percent of the time, the ice was older than 1 year.

These analyses show the variability in Antarctic sea ice drift—both during the historical age of polar exploration—as well as today. Regarding future variability, we have incorporated sea ice models into SITU for the Arctic and are currently exploring the implications of climate-changed conditions, with dramatically less summer sea ice. Some have called this change from perennial to seasonal sea ice cover the “Antarctification” of the Arctic.

American Scientist Comments and Discussion

To discuss our articles or comment on them, please share them and tag American Scientist on social media platforms. Here are links to our profiles on Twitter, Facebook, and LinkedIn.

If we re-share your post, we will moderate comments/discussion following our comments policy.

Blogs

The Long View