For years, scientists have warned about rising sea levels, but what if some of those predictions were flawed? New research has uncovered a critical miscalculation in how temperate glacier ice moves—one that could mean previous projections overestimated future sea-level rise. Published in Science, this breakthrough is reshaping climate models and our understanding of glacier dynamics. Could this discovery change how we prepare for a warming world? Let’s take a closer look.
Understanding Glacier Ice
Glacier ice isn’t all the same, and that distinction is key to understanding how glaciers move. Neal Iverson, a leading expert from Iowa State University, explains that some parts of a glacier contain temperate ice—soft, wet, and slushy, much like an ice cube melting on a countertop. Unlike cold, solid ice, this type of ice has been difficult for scientists to study in detail.
The Difference Between Cold and Temperate Ice
Not all glacier ice behaves the same way. Cold ice, which remains frozen solid like an ice cube in a freezer, has been the primary focus of past research. Most glacier models rely on data from this type of ice. However, the new study shifts attention to temperate ice, revealing that it flows differently than scientists once believed.
What Is Glen’s Flow Law and How It’s Flawed
Glen’s Flow Law has long been used to predict glacier movement, assuming ice deforms more rapidly as stress increases. While this holds true for cold ice, new research reveals it doesn’t apply to temperate ice. Scientists found that temperate ice flows in a steady, predictable way rather than accelerating dramatically under stress. This flaw means past models may have overestimated glacier flow rates—leading to inflated projections of sea-level rise.
What This Means for Sea-Level Rise
By adjusting Glen’s flow law based on these new findings, scientists now predict that temperate glaciers won’t flow into the ocean as quickly as previously thought. This means past models may have overestimated future sea-level rise, as the increased stress from climate change may not accelerate glacier movement as much as once feared.
Testing Ice in the Lab
To uncover these insights, researchers turned to a specialized ring-shear device, a tool designed to mimic the forces glaciers experience in nature. This device, funded by the National Science Foundation, has been in use since 2009. The team focused on measuring the liquid water content in temperate ice—an aspect largely unexplored since the 1970s.
The Experiment in Action
Collin Schohn, the study’s lead author, conducted six long-term experiments to better understand how temperate ice deforms. Over six weeks per test, he subjected the ice to different stress levels while keeping it at melting temperature. The goal was to track how it changed under pressure—and the results were surprising.
A Major Shift in Ice Behavior
The experiments revealed something unexpected: temperate ice deforms at a steady, predictable rate rather than accelerating under higher stress, as previously believed. This discovery challenges long-held assumptions and forces scientists to rethink how glaciers move—and, ultimately, how they contribute to rising sea levels.
Why Modeling Warm Glacier Ice Matters
Accurately modeling warm glacier ice is essential for understanding sea-level rise. Temperate ice—found at the edges and bases of fast-moving glaciers—plays a crucial role in how glaciers behave. Since these areas are often the most vulnerable to climate change, getting the science right is key to predicting their impact on the oceans.
A Key Adjustment to Glen’s Flow Law
One of the study’s biggest takeaways is that the stress exponent in Glen’s flow law needs a major revision. Instead of using a value of 3 or 4, researchers found that for temperate ice, it should be set at 1.0. This means the ice deforms in a steady, predictable way rather than accelerating dramatically under stress.
The Challenges of Studying Temperate Ice
Researching temperate ice isn’t easy. Unlike cold, solid ice, it’s softer, wetter, and harder to work with in a lab setting. Lucas Zoet, a co-author of the study and a geoscience professor at the University of Wisconsin-Madison, explained that many past studies focused on cold ice simply because temperate ice was too tricky to analyze.
A Decade of Determination
This discovery didn’t happen overnight. It took nearly ten years of research, experimentation, and overcoming setbacks to gather the necessary data. Neal Iverson reflected on the persistence required to challenge old assumptions and refine our understanding of glacier behavior.
A New Roadmap for the Future
With this breakthrough, scientists now have a more accurate way to model temperate glaciers and their impact on sea-level rise. As climate change continues to reshape the world’s ice sheets, these findings will be critical in improving predictions and guiding strategies to mitigate rising ocean levels.
