Antarctic scientists have recorded, for the first time, unusual warm water under a Florida-sized glacier, which is already melting and contributing to rising sea levels.
The researchers, working on the Thwaites glacier, recorded water temperatures at the base of the ice of more than 2 degrees Celsius, or 3.8 degrees Fahrenheit, above the normal freezing point. Critically, measurements were made on the glacier's grounding line, the area where it passes from resting entirely on the rocky bed to spreading out in the sea like ice shelves.
It is not clear how fast the glacier is deteriorating: studies have predicted its total collapse in a century and also in a few decades. The presence of hot water in the ground line can support estimates in the fastest range.
This is significant because the Thwaites, along with Pine Island Glacier and several smaller glaciers, act as a brake on part of the much larger West Antarctic ice sheet. Together, the two largest glaciers are holding ice that, if melted, would raise the world's oceans by more than a meter, or about four feet, over centuries, an amount that would put many coastal cities under water.
"The warm waters in this part of the world, however remote they may seem, should serve as a warning to all of us about the potential terrible changes caused by climate change on the planet," said David Holland, lead researcher on the expedition and director of the Dynamics Laboratory of Environmental Fluids at New York University.
Glaciologists had already warned of the presence of warm water melting the Thwaites underneath. This is the first time, however, that hot waters are measured at the glacier ground line.
To observe activity under the glacier, Dr. Holland's team drilled a hole from the surface to the bottom and then implanted equipment that measures the water temperature and the turbulence of the ocean, or the mixture of fresh water from the glacier and of the salt water of the ocean. The warm waters under the Thwaites are actively melting, according to the team.
Drilling the hole – about 30 centimeters wide and 600 meters deep, or approximately one foot by 1,970 feet – and collecting the data took about 96 hours in sub-zero weather. The results of the study are due to be published in March. The expedition was part of the Collaboration in the Thwaites International Glacier, a series of research projects that aim to understand the glacier.
"It certainly has a big impact on our U.S. coast and in many areas," said Twila Moon, a researcher at the National Snow and Ice Data Center at the University of Colorado Boulder, who was not part of the expedition.
Although scientists are still unable to definitively predict how long glaciers like the Thwaites will melt, man-made climate change is a key factor. The biggest predictor of "how much ice we will lose and how quickly we will lose it," said Moon, "is human action."