Jason Box on Greenland’s Zombie Ice

October 1, 2022

Glaciologist Jason Box of the Geological Survey of Denmark and Greenland has a new study out that got a lot of attention a few weeks back.

Here he summarizes in a helpful video. Dr. Box’s “Faster than Forecast” youtube channel is here.

Washington Post:

The new research assesses Greenland’s future through a simpler method. It tries to calculate how much ice loss from Greenland is already dictated by physics, given the current Arctic climate.

An ice sheet — like an ice cube, but at a vastly larger scale — is always in the process of melting, or growing, in response to the temperature surrounding it. But with an ice body as large as Greenland — picture the entire state of Alaska covered with ice that is one to two miles thick — adjustment takes a long time. This means that a loss can be almost inevitable, even if it has not actually happened yet.

Still, the ice sheet will leave clues as it shrinks. As it thaws, scientists think the change will manifest itself at a location called the snow line. This is the dividing line between the high altitude, bright white parts of the ice sheet that accumulate snow and mass even during the summer, and the darker, lower elevation parts that melt and contribute water to the sea. This line moves every year, depending on how warm or cool the summer is, tracking how much of Greenland melts in a given period.

The new research contends that in the current climate, the average location of the snow line must move inward and upward, leaving a smaller area in which ice would be able to accumulate. That would yield a smaller ice sheet.

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One Response to “Jason Box on Greenland’s Zombie Ice”

  1. rhymeswithgoalie Says:

    I seek a super physics nerd who actually understands the application of differential equations to tell me how much chilly meltwater actually counteracts the thermal expansion of the existing sea water.

    That is, if there were no ice caps or glaciers, all of the ocean expansion would be from a fixed mass of water being thermally expanded. Conversely, if we instantaneously put all of the meltwater into the existing ocean, all of the ocean expansion would be from pouring in more water. So how does the combination of cooler-than-average meltwater being added to ocean with an increasing heat content net out into total mean global SLR?


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