It’s well known now that massive glaciers in Greenland and Antarctica are contributing to an accelerating global sea level rise. And while we first thought Greenland was primarily at risk of producing ocean-lifting melt this Century, we have now learned that both West and East Antarctica are becoming involved.

(A massive glacier the size of France is floating on more of a warming ocean than previously thought. Taking into account past reports of thinning along the glacier’s underside, and this is a rather concerning finding. Image source: Australian Antarctic Division.)

How much and how soon and under how much warming pressure is still a matter of some debate in the sciences. But the situation is now looking a bit worse for the Totten Glacier — an enormous sea-fronting slab of ice as big as France that if it melted in total would, by itself, raise sea levels by about 10-13 feet globally.

Previously thought to be more resilient to melt as a result of human-caused climate change and related fossil fuel burning, the Totten was once considered to be stable. However, over recent years, concerns were raised first when plumes of warm water were identified approaching the glacier’s base and later when it was confirmed that Totten was melting from below. Concerns that were heightened by new research identifying how winds associated with climate change were driving warmer waters closer and closer to the huge ice slab.

(Winds heated by climate change drove warmer waters toward Totten and accelerated the glacier during recent years. Video source: Science News.)

After follow-on expeditions to Totten, scientists (over the past two years) discovered that the glacier’s floating underside was losing about 10 meters of thickness annually even as its seaward motion was speeding up. Now, new research has found that more of the Totten Glacier is floating upon this warming flood of ocean water than previously thought. According to Professor Paul Winberry, from Central Washington University, who spent the austral summer of 2018 with a Tasmania-funded team of scientists taking measurements of Totten:

“A hammer-generated seismic wave was used to ‘see’ through a couple of kilometres of ice. In some locations we thought were grounded, we detected the ocean below indicating that the glacier is in fact floating (emphasis added).”

Beneath Totten lies a large ridge upon which most of the glacier is grounded as it flows toward the sea. But penetrating this ridge are numerous gateways that, if melted through, provide sea water access to the glacier’s interior. And recent studies have found that a number of these gateways have been thawed open, allowing warming ocean waters access to sections of the glacier that are hundreds of miles inland.

(Warm water invasion pathways have opened along Totten’s previous grounding line. These openings have allowed water to flood far inland beneath the glacier. The result is a less stable, more rapidly moving ice sheet. Image source: Jamin Greenbaum/University of Texas-Austin.)

This warm water breakthrough has contributed to Totten’s seaward movement. And the new study was aimed at discovering the extent of the inland water melt flood. According to lead researcher Dr Galton-Fenzi:

“These precise measurements of Totten Glacier are vital to monitoring changes and understanding them in the context of natural variations and the research is an important step in assessing the potential impact on sea-level under various future scenarios.”

The fact that the extent of inland flooding along Totten’s underside runs further than previously thought is a concern in light of recent findings that the glacier is losing a considerable amount of underbelly ice each year. In addition, the fact that we haven’t yet pinpointed the grounding line should add another note of worry. How much we should worry is unclear at this time. But the fact is that the scientific signs coming in from Totten continue to indicate that the glacier is suffering warming impacts that pose risks to its historic stability.