Members of our broader research group are working extensively in the field. This especially involves the International Thwaites Glacier Collaboration, the major project to learn what is going on in the most vulnerable part of the most vulnerable ice sheet in the Antarctic, the West Antarctic Ice Sheet, which includes the Thwaites Glacier. After seasons lost to Covid, a major expedition will be traversing down Thwaites, using radars, seismic sensors and more to characterize the ice and its bed.
Other groups are working farther downstream, extending work that has been done on the ice shelf and in the ocean beyond. Thwaites is vast, larger than the state of Florida. It is some 80 miles across, making it arguably the widest glacier on Earth. Since the 1990s, scientists have reported on the increased velocity of its movement and the doubling of its contribution to sea-level rise. Its collapse would trigger meters of sea-level rise in the decades and centuries to come, hence its popular nickname in the media, Doomsday Glacier.
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What are the challenges in predicting how much warming will ultimately cause the Thwaites Glacier to break apart?
Some of this is really difficult, especially where fractures are involved. Think about ceramic coffee cups dropped on hard floors. Sometimes the coffee cup just bounces, or the rim chips, or the handle breaks off, but sometimes the whole thing shatters. Scientists can accurately predict the average behavior of a lot of coffee cups dropped on a lot of floors, if you tell us the height of the drop, the type of floor, the type of cup and a few other things. But predicting the exact behavior of the next cup dropped is really difficult, in part because the behavior depends on whether there are small cracks buried deep in the material of the cup, among others. Predicting exactly how much warming is needed to break parts of Thwaites will be harder than predicting coffee cups.
Sounds like there’s still a lot of uncertainty here. How should policymakers cope with that?
First of all, the uncertainties are not our friend. There is basically no way that sea-level rise can be notably smaller than expected. When we make the climate warmer, the ocean warms up. That makes the water expand, which raises sea level. That’s relatively easy.
The glaciers in the mountains are doing what we projected decades ago: They really are melting. That takes water that was ice out of the mountains and puts it into the ocean, and that raises sea level. Those are fairly easy predictions. There are not large uncertainties in those. The uncertainties are: Will the ice shelves break off, will the flow of the big ice sheets change a lot, with the potential to drive these very large, rapid sea-level rises. So the uncertainties are on the bad side.
In other areas of our lives, we tend to invest a lot to avoid the possibility of a catastrophe, even if we are not sure it is going to happen. The example I like to use is highway safety. We have highway engineers, we have crumple zones in the car, we have airbags and antilock brakes and seatbelts and we have police out there trying to stop drunken drivers. We are not very likely to get killed by a drunken driver, but the catastrophe would be so bad if it happened that we invest a lot in heading that off.
What would make sense may be to think about sea-level rise and our response to it with the same sort of lens: There are things we can do to better understand why it happens and what the causes are. Next steps might be communities taking steps that reflect scientific findings, which of course have economic as well as social benefits.
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