New research has revealed that an Antarctic ice shelf is breaking apart from the inside out and could cause sea levels to rise. A study produced by the Australian National University (ANU), in collaboration with the University of Tasmania and Belgium’s Université catholique de Louvain, shows that the glacier, known as the Totten Glacier in East Antarctica, is losing ice because of warm ocean water. The glacier is responsible for more than 70% of the ice discharge from East Antarctica and holds enough ice to raise sea levels by at least 3.5m.
The researchers found that the glacier is experiencing rapid melt caused by contact with warm ocean waters, responsible for approximately 90% of the heat entering the Earth’s oceans. The rate of Antarctic melting suggests that the estimated impact of sea level rise has been underestimated. Further significant rises could threaten low-lying cities and countries including Bangladesh, Vietnam, and the Netherlands. The process of ocean warming in Antarctica is causing melting to take place from the ice shelf’s underside rather than via melt water runoff from above, which could have implications for future sea level rise.
The cause of the warm water intrusion is partly due to changes in wind currents, caused by both human-induced climate change and natural phenomena such as El Niño. While natural variability is a factor, the human impact is exacerbating the melting of Antarctica, with some scientists believing that it is a critical “tipping point” in climate change.
Melting from the Totten Glacier could cause sea levels to rise by at least 2.9 metres, a process that could take centuries or accelerate over just a few decades. The melting rate is currently unclear, but ANU Glaciologist and the study’s lead author, Dr Stephen Galton-Fenzi, warned that the implications of the melting process could be significant: “if the melting of the Totten Glacier continues at its current rate, it could cause major changes to global coastlines and impact on weather patterns and temperatures across the world.”
The research highlights the potential for a feedback loop, whereby melting ice causes circulation changes in the ocean, which in turn cause more melting of the ice. As Dr Galton-Fenzi stated: “When this overturning slows, it opens a pathway for warmer waters which could cause increased melt, which would be a further feedback, putting more meltwater into the ocean and slowing down this circulation even more.”