A gigantic cavity – two-thirds the area of Manhattan and almost 1,000 feet (300 meters) tall – growing at the bottom of Thwaites Glacier in West Antarctica, is the finding of a NASA-led study recently published on Science Advances.
Researchers expected to find some gaps between ice and bedrock at Thwaites’ bottom where ocean water could flow in and melt the glacier from below. The size and explosive growth rate of the newfound hole, however, surprised them. It’s big enough to have contained 14 billion tons of ice, and most of that ice melted over the last three years.
We asked a comment to Dorotea Iovino, CMCC scientist at ODA – Ocean modeling and Data Assimilation Division and Principal Investigator of the INVASI project.
“Although climatic trends in and around Antarctica are predominantly controlled by internal variability and natural mechanisms”, she explains, “this cavity is at least partially related to the warming of the ocean. The cavity has been forming over the past 3 years as newly discovered limb of warm water has flowed into glacier cracks, steadily melting the ice. The more heat under the glacier, the faster the melting.”
So, what are major implications and in particular threats emerging from these results?
“The size of Thwaites glacier is huge and contains vast amounts of ice above sea level that if transported into the ocean would affect global sea level significantly”, researcher Iovino explains, “raising global sea level by around 65cm. The Thwaites glacier melting will free the path of warm ocean water to surrounding glaciers, accelerating their melting and the potential water release, large enough to raise sea level up to 2.4m”.
The study highlighted a complex pattern of retreat and ice melt, with sectors retreating at 0.8 km/year and floating ice melting at 200 m/year, while others retreat at 0.3 km/year with ice melting 10 times slower. Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models.
“Over the last decade, there has been a total transformation in our abilities to understand and predict the behaviour of the ice sheets, but there is still work to be done to properly understand the processes that lead to ice loss on Thwaites and to reduce the uncertainty in future sea-level projections”, Dr. Iovino concluded.