A Trip to Totten Glacier
I grabbed the hand rail as the ship shuddered against a massive chunk of ice. No-one had slept for days. The constant roar of the engines and ramming of the ship into the sea ice made sleep impossible. Some days we travelled mere metres, Adelie and Emperor penguins stopping to look at us on their way across the ice, easily overtaking our slow progress as they tobogganed along on their bellies. Other days we would find a lee in the ice and travel at speed, the sea ice crumbling like tissue paper under the bulk of the icebreaker. But all the while, we were fighting the clock. The only reason we were able to travel to Totten Glacier was because the winds had favoured us, blowing the sea ice away from the edge of the ice shelf. If the winds changed and blew the sea ice back, we would be stuck, the ship crammed between the layers of ice.
So it is with great trepidation and urgency that we watched, hoping to catch our first glimpse of Totten Glacier, the largest glacial ice shelf of East Antarctica. East Antarctica is a region that stores so much ice that, if it were to melt, global sea levels would rise tens of metres. Totten alone could lead to 3.5m of sea-level rise if it were to melt, and understanding the conditions influencing the ice shelf stability and the effects of our changing climate are vital to understanding and mitigating the risks of climate change.
It took days for us to navigate through the thick sea ice and around the giant icebergs before we sighted Totten. We were the first to ever reach those waters. Standing on the deck of the ship, one of the expeditioners commented that we were explorers, real explorers, pioneering into places on the earth never before touched.
We emerged into an area of open water, known as a polynya, a welcome break from the ramming of sea ice. It is the polynya that we had been looking for, as it formed in front of the Totten ice shelf. Every moment we were there was precious, the winds could change at any second, forcing us to abandon our post and return to the relative safety of the open ocean. We rushed to take as many measurements as possible. We cast CTDs (Conductivity i.e salinity, Temperature and Depth), captured acoustic doppler data of the currents and collected water samples in large niskin bottles providing us with information of salinity, helium, dissolved oxygen, nutrients, alkalinity, and dissolved inorganic carbon (TCO2). Our hands froze as we bottled the samples and the icy sea water covered our fingers, the smell of brine and the squeak of our gumboots filling the air. We cherished every last sample, but it was not long before we had no choice but to retreat as the risk of dangerous conditions intensified.
The measurements from the January 2015 expedition produced a picture of the flow and conditions of the waters in front of Totten ice shelf. This data provided the first indication of warm waters in the area near Totten Glacier (Rintoul et al., 2016, Silvano et al., 2016, Silvano et al., 2017). While these measurements are now nearly ten years old, they have been fundamental in understanding Totten glacier and the sensitivity of East Antarctica to climate change. Totten is melting faster than any other glacier in the region and remains an important avenue of research, with further measurements continuing to provide insight into East Antarctica and the warm waters near Totten Glacier (Nakayama et al., 2023, Hirano et al., 2023).
East Antarctica has the potential for widespread ice loss if global temperatures continue to rise (Stokes et al., 2022). Significant mass loss could be prevented by limiting climate warming (Stokes et al., 2022), highlighting the need for urgent action and the importance of understanding and protecting these remote and fragile environments.
The 2014-2015 science expedition was led by Steve Rintoul, CSIRO.
References:
Rintoul et al., 2016, Ocean heat drives rapid basal melt of the Totten Ice Shelf, Science Advances, 2, 12, DOI: 10.1126/sciadv.1601610
Silvano et al., 2017, Distribution of water masses and meltwater on the continental shelf near the Totten and Moscow University ice shelves, Journal of Geophysical Research: Oceans, https://doi.org/10.1002/2016JC012115
Silvano, A., S.R. Rintoul, and L. Herraiz-Borreguero. 2016. Ocean-ice shelf interaction in East Antarctica. Oceanography 29(4):130–143, https://doi.org/10.5670/Oceanog.2016.105.
Stokes, C.R., Abram, N.J., Bentley, M.J. et al. Response of the East Antarctic Ice Sheet to past and future climate change. Nature 608, 275–286 (2022). https://doi.org/10.1038/s41586-022-04946-0
Hirano, D., Tamura, T., Kusahara, K. et al. On-shelf circulation of warm water toward the Totten Ice Shelf in East Antarctica. Nat Commun 14, 4955 (2023). https://doi.org/10.1038/s41467-023-39764-z
Nakayama et al., 2023, Helicopter-Based Ocean Observations Capture Broad Ocean Heat Intrusions Toward the Totten Ice Shelf, Geophysical Research Letter, https://doi.org/10.1029/2022GL097864
