Scientists Just Measured the Fastest-Moving Glacier on Earth

Glaciers are often described as slow-moving rivers of ice, but some can accelerate to remarkable speeds under certain conditions. Recent satellite observations confirm that Jakobshavn Isbræ in western Greenland has reached some of the fastest flow rates ever recorded for an outlet glacier.

Using interferometric synthetic aperture radar data from NASA’s Operation IceBridge and the European Space Agency’s Sentinel satellites, researchers measured peak velocities exceeding 17 kilometers per year during acceleration phases. Findings published in The Cryosphere and Geophysical Research Letters document how this glacier’s speed fluctuates in response to ocean temperature and ice front position.

Why Jakobshavn Moves So Quickly

Jakobshavn drains a significant portion of the Greenland Ice Sheet into a deep fjord connected to the North Atlantic Ocean. The glacier’s grounding line lies below sea level, which makes it sensitive to changes in ocean heat content. When relatively warm Atlantic water enters the fjord, it melts the glacier’s underside, reducing friction at its base and accelerating ice discharge.

Glaciologist Ian Joughin of the University of Washington has explained that the glacier’s speed responds strongly to ocean forcing. When warm water penetrates beneath the floating ice tongue, it destabilizes the terminus and allows inland ice to flow more rapidly toward the sea. The glacier briefly slowed between 2016 and 2018 during a period of cooler ocean conditions, but subsequent warming has again increased flow rates.

Satellite Monitoring and Ice Sheet Stability

Modern satellite radar systems can detect surface displacement with centimeter precision by comparing repeated images. These measurements provide continuous monitoring of glacier velocity, thickness, and terminus retreat.

Eric Rignot of NASA’s Jet Propulsion Laboratory has emphasized that outlet glaciers like Jakobshavn act as gateways through which interior ice drains into the ocean. When these glaciers accelerate, they can amplify overall ice sheet mass loss.

Implications for Sea Level Rise

Jakobshavn has been one of the largest contributors to Greenland’s contribution to global sea level rise over the past two decades. Faster ice discharge increases the transfer of land-based ice into the ocean, raising global sea levels.

Although short-term variability arises from ocean cycles, long-term projections suggest that continued warming could sustain or increase acceleration. Understanding the physical mechanisms that drive glacier speed remains essential for improving sea-level rise projections used by coastal planners worldwide.