West Antarctic Ice Sheet Retreat: The 2014 NASA Study and Thwaites Today

In May 2014, NASA announced that a group of fast-moving glaciers in West Antarctica had passed the point of no return. A team led by glaciologist Eric Rignot of NASA's Jet Propulsion Laboratory and the University of California, Irvine, concluded that ice loss from the Amundsen Sea sector "appears unstoppable", a result that put Thwaites and Pine Island glaciers on front pages around the world.

The 2014 NASA West Antarctic glacier study

Rignot's team, publishing in Geophysical Research Letters, used satellite measurements to track six glaciers draining into the Amundsen Sea: Pine Island, Thwaites, Haynes, Pope, Smith and Kohler. The findings were stark:

• Between 1992 and 2011, Pine Island Glacier's grounding line retreated 31 km (19 miles), and the centre of Thwaites retreated about 14 km (9 miles).
• The amount of ice flowing from the region into the sea had risen by 77 percent since 1973.
• The team found no hills or bumps in the bedrock behind the glaciers that could stop the retreat.

A separate study published in Science, led by Ian Joughin of the University of Washington, used computer models and estimated that Thwaites could enter rapid, irreversible collapse in roughly 200 to 900 years unless warming stays minimal.

How much sea-level rise is at stake

The Amundsen Sea Embayment is only a fraction of the West Antarctic Ice Sheet, but it holds enough ice to raise global sea level by about 1.2 metres (4 feet). The whole West Antarctic Ice Sheet, if it melted completely, would add several metres more; NASA's primer gave a figure of about 5 metres (16 feet).

The timescale is long. NASA's conservative estimate was that the loss of the Amundsen Sea glaciers would take several centuries. That is slow by human standards and very fast by geological ones, and it would reshape coastlines everywhere. Interactive tools such as Climate Central's Surging Seas show which coasts sit lowest.

Why grounding lines matter

The grounding line is the point where a glacier lifts off its bed and starts to float as an ice shelf. Much of West Antarctica rests on bedrock far below sea level, and the bed slopes downward inland. When warm ocean water reaches the grounding line, it melts the ice from below and the line retreats into ever deeper water.

The warm water comes from a deep ocean current steered towards the coast by the shape of the seafloor, first observed reaching these glaciers in the 1990s. As ice shelves thin, they push back less against the ice behind them, so the glaciers speed up, thin and feed more ice to the sea. NASA's video below shows the flow speeds and elevation change across the region.

Thwaites Glacier research since 2014

Thwaites became the focus of the International Thwaites Glacier Collaboration, a joint US–UK programme that began fieldwork in 2018. The glacier is about 120 km wide, the widest on Earth, covers an area about the size of Great Britain or Florida and is more than 2,000 m thick in places. Its complete collapse would raise sea level by about 65 cm.

In September 2024, the collaboration's scientists met at the British Antarctic Survey in Cambridge to present results from underwater robots, new surveys and improved models. They reported that:

• Thwaites has been retreating for more than 80 years, and the retreat has sped up over the past 30.
• Ice flow from Thwaites and its neighbours more than doubled between the 1990s and 2010s.
• The Amundsen Sea Embayment now supplies about 8 percent of global sea-level rise, which runs at 4.6 mm a year.
• Thwaites and much of the West Antarctic Ice Sheet could be lost by the 23rd century.

Ted Scambos, the programme's US science coordinator, summed up the role of emissions: "Immediate and sustained climate intervention will have a positive effect, but a delayed one." Warm deep ocean water remains the main driver, and the sooner warming is limited, the more it helps.

The glacier is named after Fredrik T. Thwaites (1883–1961), a glacial geologist at the University of Wisconsin–Madison who never visited it. The nickname "Doomsday Glacier" came from a 2017 magazine article, and several leading glaciologists, Rignot and Scambos among them, consider it alarmist.

Related reading

• glacier change in repeat photographs
• sea ice and land ice explained
• The Ilulissat Calving Sequence in Chasing Ice
• Blood Falls, Antarctica: Iron-Rich Brine at Taylor Glacier
• Gentoo Penguins at Neko Harbour: When a Glacier View Changes Scale
• Antarctic Condition 1 Weather: The View through a Station Door
• Lake Hodgson: Microbial Evidence from Antarctic Sediments

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