“Warm ice” was not taken into account when building models of ocean level rise

18.01.2025/12/30 XNUMX:XNUMX    231

A new study indicates that glaciers are sliding into the ocean much more slowly than previous models predicted, which could significantly change projections of sea level rise due to global warming.

by @freepik

Scientists led by Neil Iverson, a professor at Iowa State University, focused on “warm” ice — the parts of glaciers that melt under pressure and become soft. This type of ice, which looks like a cube melting on a table, is the most important for understanding how glaciers slide into the sea, because that’s where the most activity occurs. But traditional models have mostly been based on studying “cold” ice, which is harder and less dynamic, which may explain the overestimated predictions.

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A study published in the journal Science, found that the standard equation describing the speed of glacier flow, in particular Glen's law, needed to be corrected for "warm" ice. Experiments using a special ring shear device in Iverson's laboratory showed that ice at moderate temperatures deforms at a rate proportional to stress, but does not soften in response to increasing stress, as previously assumed.

These experiments also revealed that ice grains within the ice change during deformation: they triple in size and form more jagged boundaries. This melting and refreezing at grain boundaries slows the movement of glaciers, which is critical for assessing their contribution to sea level rise.

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The results of the study are important for refining forecasts, especially for the “warm” zones of glaciers, which have the fastest impact on ocean levels. The scientists do not specify exact figures for the possible decrease in projected sea levels, since they specialize in the physics of glaciers. However, their work provides new tools for creating more accurate models of glacier melting.

This study not only changes the approach to assessing the impact of glaciers on the ocean, but also shows how basic physical processes—such as the movement of ice grains and their interactions—influence global climate projections.





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