The development of an expanding network of meltwater lakes adjacent to the Greenland ice sheet is contributing to an increase in the flow rate of significant glaciers, thereby augmenting global sea-level rise. Since 2002, around 264 gigatons of ice have been lost annually in Greenland due to rising air and sea temperatures, causing sea levels to rise by about 0.8 millimeters each year. A recent study conducted by the University of Leeds has illuminated the impact of a lesser-known element associated with glacier dynamics—specifically, the freshwater lakes that form as the ice retreats.
These ice-marginal lakes (IMLs) form directly against the glacier edge as the glaciers recede, revealing deep, bowl-shaped depressions in the topography. Meltwater rapidly accumulates in these basins, resulting in lakes that can extend over an area of 117 km².
The study, published in the journal Communications Earth and Environment, reveals that these lakes are not merely passive features but can, in fact, destabilize the glaciers feeding into them. This destabilization can trigger increased glacier movement, heighten thinning rates, and lead to accelerated ice loss.
Using satellite data and mapping the distribution of ice-marginal lakes across Greenland, the researchers analyzed the flow behavior of the ice sheet's surface. They discovered that the flow rate of glaciers terminating in lakes is more than three times greater at their front compared to those that end on land. Notably, this acceleration extends up to 3.5 kilometers inland from the glacier margin.
Connie Harpur, the study's lead author and a postgraduate researcher in Leeds' School of Geography, remarked, "Our findings are significant because glacier speed plays a major role in how quickly ice is lost from the Greenland Ice Sheet. When glaciers flow faster, they deliver more ice to lower elevations, where it can melt, or to their fronts, where it can break away."
Currently, approximately 10% of Greenland's ice edge is bordered by freshwater lakes, a figure anticipated to increase significantly as climate change persists and more depressions are exposed during the retreat of ice. Similar to glaciers that flow into the ocean, those terminating in lakes experience a form of flotation. This results in the partial lifting of the glacier front, intensifying melting beneath the ice and facilitating the calving process, wherein large segments of ice break away. Additionally, the presence of water reduces the friction that typically acts to slow down glacier flow.
The researchers at Leeds caution that neglecting these dynamics could have significant implications. Ice dynamics—characterizing how glaciers accelerate, decelerate, and deform—are projected to be the foremost contributor to Greenland's ice loss in the upcoming decades. As lake formation progresses in parallel with climate warming, the authors argue for the urgent integration of IMLs' effects into predictive models.
Co-author Professor Mark Smith emphasized, "If we do not account for lake effects, we may underestimate how dynamically parts of the ice sheet respond to future warming, and in turn how much Greenland will contribute to future sea level rise. Understanding the influence of ice-marginal lakes on glacier flow is crucial for accurate projections."
Publication details
Harper, C. M., et al, Ice-marginal proglacial lakes enhance outlet glacier velocities across Greenland, Communications Earth & Environment (2026). DOI: 10.1038/s43247-026-03363-9
Key concepts
- Ice sheet
- Sea-level change
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