The observation by a team of scientists for the first time, about the presence of warm water at a vital point underneath a glacier in Antarctica, is an alarming discovery that points to the cause behind the gradual melting of this ice shelf while also raising concerns about sea-level rise around the globe.
If these waters are causing glacier melt in Antarctica, resulting changes in sea level would be felt in more inhabited parts of the world. The recorded warm waters – more than two degrees above freezing – flow beneath the Thwaites Glacier, which is part of the Western Antarctic Ice Sheet.
The discovery was made at the glacier’s grounding zone – the place at which the ice transitions between resting fully on bedrock and floating on the ocean as an ice shelf and which is key to the overall rate of retreat of a glacier.
Thwaites’ demise alone could have significant impact globally. It would drain a mass of water that is roughly the size of Great Britain or the state of Florida and currently accounts for about 4% of global sea-level rise. Some scientists see Thwaites as the most vulnerable and most significant glacier in the world in terms of future global sea-level rise – its collapse would raise global sea levels by nearly one metre, perhaps overwhelming existing populated areas. While the glacier’s recession has been observed over the past decade, the causes behind this change had previously not been determined. It may be noted that the Thwaites Glacier has lost 600bn tonnes of ice over the past several decades, accelerating to as many as 50bn tonnes per year in recent years.
“The fact that such warm water was just now recorded by our team along a section of Thwaites grounding zone where we have known the glacier is melting suggests that it may be undergoing an unstoppable retreat that has huge implications for global sea level rise,” noted David Holland, director of New York University’s (NYU) Environmental Fluid Dynamics Laboratory, and a professor at Courant Institute of Mathematical Sciences, in a statement. The scientists’ measurements were made in early January, after the research team created a 600m deep and 35cm wide access hole and deployed an ocean-sensing device to measure the waters moving below the glacier’s surface. This device gauges the turbulence of the water as well as other properties such as temperature. The result of turbulence is the mixing of fresh meltwater from the glacier and salty water from the ocean.
It marks the first time that ocean activity beneath the Thwaites Glacier has been accessed through a bore hole and that a scientific instrument measuring underlying ocean turbulence and mixing has been deployed. The hole was opened on January 8-9 and the waters beneath the glacier measured on January 10-11. Aurora Basinski, an NYU graduate student who made the turbulence measurement, said, “From our observations into the ocean cavity at the grounding zone we observed not only the presence of warm water, but also its turbulence level and thus its efficiency to melt the ice shelf base.”
Scientists refer to Thwaites as the “doomsday glacier” due to the dire implications its rapid melting could have for the planet. Though a 10-ft sea-level rise would likely take years, the melting of the glacier could eventually mean the US would lose 28,800sq miles of coastal land – pushing 12.3mn people currently living in those areas out of their homes.