The Doomsday Glacier

You may have heard about the so called “Doomsday Glacier.” If you haven’t, you’re going to today. It’s official name is Thwaites Glacier and it’s part of a larger glacial system called the West Antarctic Ice Sheet (WAIS). The reason it’s being called “Doomsday” is that scientists have discovered that it’s being eroded from the bottom by warm seawater.

As more of its underside melts, the grounding line retreats. The graphic shows how the ground slopes downward behind the bedrock mound against which the glacier is pinned. This allows seawater to advance and melt more of the bottom ice. At some point, the “lubrication” provided by liquid water could allow the entire glacier to slide into the ocean. Total collapse could happen in this century, and it would raise ocean levels by around 65 cm (25 inches).

Thwaites is moving downhill around 2 km each year, but that rate is accelerating. As the floating ice shelf advances ocean swells and tides cause it flex and crack, calving off large icebergs. That process is already contributing 4% of the total global rise in sea level. Since 2000, Thwaites has lost 1000 billion tons of ice. This photo shows the leading edge of the floating ice shelf. At it’s widest part, it measures 120 km (80 miles):

Thwaites Glacier has an area of 192,000 km2. That’s slightly more than the size of Florida at 170,000 km2. This graphic shows a scaled version of Florida (pink area) superimposed over the location of Thwaites in Antarctica. Florida was flipped horizontally to better match the glacier’s ice field:

Scientists only recently discovered what was happening under Thwaites. They drilled a borehole to the bottom of the glacier and also used a remotely controlled underwater drone. What they found is shown in the top graphic. If the melting continues to accelerate, the total collapse of Thwaites could occur in this century.

The larger worry is that the collapse of Thwaites (the largest single glacier in the WAIS) could trigger the collapse of all the other glaciers in the WAIS. Although this would take a few centuries to millennia, it would raise sea levels by another 3.3 m (11 feet).

It’s a bit ironic that the sizes of Thwaites and Florida are often used in comparisons. 3.3 meters of sea level rise would pretty much wipe out most of the low-lying state. Even the 65 cm from Thwaites alone would wreak havoc. Coastal areas around the globe, where the majority of people live, would be devastated. Surprisingly, even Yuma, AZ could find itself with beachfront properties!

So you can see why they call it the “Doomsday Glacier.” It’s one of many unfortunate consequences of climate change. Antarctica may seem a long distance off, but the impacts of climate change are global.

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