New Research Reveals Faster Glacial Melt Than Previously Predicted Due to Ice Viscosity Miscalculation

Glacial Ice Viscosity Models May Underestimate Future Sea Level Rise

Models predicting glacial flow and retreat rely heavily on estimates of glacial ice viscosity—the measure of ice’s resistance to deformation under stress. A critical variable in these models is the stress exponent (n), which determines how sensitive ice viscosity is to changes in applied stress.

For decades, glaciologists have used an assumed n value of 3 in ice sheet models. However, new research published in AGU Advances suggests that an n value of 4 may better represent real-world conditions in Earth’s ice sheets and glaciers.

Pine Island Glacier Study Highlights Model Flaws

Researchers led by Martin et al. developed a model of the Pine Island Glacier in West Antarctica, a fast-retreating glacier critical to sea level projections. Their model incorporated a true n value of 4 but was tested against projections using both n = 4 and n = 3 to assess discrepancies.

The team simulated glacial retreat over 100 years under two melting scenarios—moderate and extreme—followed by a 300-year recovery period. The results revealed significant underestimations in the n = 3 model:

• Moderate melting scenario: Glacial retreat was underestimated by 18%, while sea level contributions were underestimated by 21%.
• Extreme melting scenario: Sea level contributions were underestimated by 35%.

The disparities between the two models were larger than expected, raising concerns about the reliability of current sea level rise projections. The researchers warn that incorrect n values may lead to misattributions of other physical processes in ice sheet models, further skewing predictions.

Implications for Future Sea Level Projections

The findings suggest that glacial melt rates—and consequently, sea level rise—could occur faster than previously anticipated. The authors emphasize the need for further investigation into how these revised models impact long-term climate and coastal planning.

"The results could have far-reaching implications for predictions of future glacial melt and may prompt investigations into its effects on sea level."

Key Takeaways

• Glacial ice viscosity models have long used an n value of 3 to predict flow and retreat.
• New research suggests an n value of 4 may be more accurate for real-world conditions.
• Using n = 3 underestimates glacial retreat by 18% and sea level contributions by 21–35%.
• These discrepancies could increase uncertainty in sea level rise projections.
• The study calls for reevaluating current ice sheet models to improve climate predictions.