Predicting the future behavior of Thwaites, the Doomsday Glacier

Scientists have mapped the ground beneath Antarctica’s most vulnerable glacier, Thwaites, for the first time. This breakthrough will aid researchers in understanding the impacts of climate change on this sensitive area.

Thwaites Glacier, a massive formation in West Antarctica comparable in size to Great Britain or the US state of Florida, is one of Antarctica’s fastest-changing ice-ocean systems. 

Geophysicist Dr. Tom Jordan, who spearheaded this study at the British Antarctic Survey (BAS), emphasized that the findings are vital due to the glacier’s rapid transformation.

A few surprises revealed in the data

The study, published in the journal Science Advances, revealed that the area beneath the Thwaites Glacier had less sedimentary rock than anticipated. “Sediments allow faster flow, like sliding on mud,” Dr. Jordan explained. 

Understanding the location of these slippery sediments, he noted, would help predict the glacier’s future behavior as it retreats.

The researchers noticed significant changes at the glacier’s grounding zone – the spot where it interacts with the seafloor. Since the late 1990s, this point has retreated a staggering 14 km. 

Notably, much of the ice sheet rests below sea level, which makes it prone to rapid, irreversible ice loss that could result in a global sea-level rise of over half a meter within centuries.

How the study was conducted

This groundbreaking research involved airborne surveys using specially equipped aircraft. These planes housed radar that could penetrate the ice to the rocks beneath, as well as sensors to map minute variations in gravity and magnetism. The instruments operated hundreds to thousands of meters below the ground and seabed where the glacier rests.

In combining the data from these various sources, researchers compiled a 3D representation of several features, including the type and extent of different rocks. 

Dr. Jordan pointed out the importance of the integrated nature of these airborne surveys: “Each sensor on the aircraft provided an important but incomplete part of the picture, but by bringing them all together we could provide the detailed map of the underlying geology.”

The study delves into geological history, tracing back to when New Zealand separated from Antarctica around 100 million years ago, long before the formation of the Thwaites Glacier. 

Researchers anticipated the discovery of thick sediments at the base of Thwaites Glacier, given its position below sea level and the geological processes of millions of years. Previous analyses of other Antarctic glaciers indicated the presence of thick underlying sediments.

However, the survey data indicated that sedimentary rock constitutes only about a fifth of the ground beneath the Thwaites Glacier. These sediments are scattered in basins ranging between 80 and 200 km in length and about 30 km wide. The remainder of the ground comprises diverse geological bodies, including granite peaks and other hard rocks. The researchers hypothesized that the sedimentary basins were once larger but were eroded down to bedrock due to glacier movement.

Implications of the results are unclear

The implications of these findings for estimates of ice flow and loss from Thwaites and other glaciers remain unclear. Yet, the study demonstrates that the geological landscape directly impacts the basal shear stress, a key determinant of the speed at which ice can flow into the ocean.

Dr. Jordan expressed his hopes for the study’s implications: “We hope that by showing the detailed geology, and how it correlates with the basal friction, future models of glacial retreat will have lower uncertainty, as the controls of the basal processes will be better understood.”

“No single scientific study could ever match the scale and challenge of climate change. But it is the incremental building of all the individual scientific studies like this that allows us to understand and tackle that challenge.”

The team will proceed with more detailed studies of these processes. The newly discovered data may also assist in creating more accurate predictions of future ice loss. 

Study co-author and glaciologist Dr. Sarah Thompson added an optimistic note: “The integrated approach used in this study has significant potential for successful application elsewhere in Antarctica, enabling us to explore other potentially vulnerable regions where current knowledge is sparse.”

Much more research is needed

This research project has opened a new dimension in the understanding of Antarctic glaciers and their response to climate change. Its innovative approach to mapping the geology beneath the ice has shed light on how the structure and composition of the earth beneath a glacier can influence its flow rate and melting process.

More research is forthcoming, and with it, we may gain better predictions about how these massive glaciers will behave in the future. As the team dives deeper into this exciting new knowledge base, the global scientific community eagerly anticipates further insights into our changing world.

While we grapple with the grand challenges of climate change, research endeavors such as this one from the British Antarctic Survey provide us with crucial knowledge and tools. 

Incrementally, we are building a scientific understanding robust enough to tackle the profound environmental transformations of our time. This study is an important piece of the jigsaw puzzle, highlighting the inextricable ties between our planet’s geology and climate.

More about the Thwaites Glacier

Thwaites Glacier, also known as the “Doomsday Glacier,” is located in the remote Amundsen Sea in West Antarctica. It’s a wide and fast-flowing glacier, roughly the size of Florida or Great Britain, and it has been a significant focus of scientific study due to its sensitivity to climate change.

Thwaites Glacier is one of the most vulnerable and important glaciers in the world in terms of future global sea-level rise. It is believed that the glacier is undergoing significant change due to warming oceans, and this change is accelerating.

Accelerating pace of ice loss is troubling 

In the past few decades, the speed at which Thwaites Glacier is flowing into the sea has nearly doubled. Satellite measurements have shown that the glacier is losing an enormous amount of ice each year, nearly 50 billion tons annually, contributing to rising global sea levels. If the entire Thwaites Glacier were to melt, it could raise the world’s oceans by about 65 centimeters (over 2 feet).

A critical concern is that much of Thwaites sits on land that is below sea level, in a configuration known as “marine-based.” This situation means that as the glacier’s grounding line – the point where the glacier’s ice lifts off the land and starts floating on the sea – retreats inland, it can pass over deeper and deeper valleys. This process allows more and more ice to discharge into the sea, which might accelerate the glacier’s melt in a phenomenon known as “marine ice sheet instability.”

Collapse of Thwaites would cause disastrous chain reaction

The stability of Thwaites is also important because it backs up other glaciers, acting as a kind of doorstop, and preventing the ice in these glaciers from flowing into the sea. The collapse of Thwaites could potentially destabilize a larger part of the West Antarctic Ice Sheet, which contains enough ice to raise sea levels by an additional several meters.

Despite its remote location, research teams from around the world have been traveling to Thwaites for study. They’re using ice-penetrating radar and other instruments to map the ice and the sea floor, and are drilling into the glacier to understand its stability and the factors affecting its rapid change.

—-

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.