Jakobshavn Isbræ

Jakobshavn Isbræ
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Name	Jakobshavn Isbræ
Photo caption	Satellite image of Jakobshavn Isbræ from NASA.
Type	Tidewater glacier
Location	Greenland, near Ilulissat
Coordinates	69, 10, N, 49...
Length	~65 km
Thickness	~2,000 m
Terminus	Ilulissat Icefjord (Disko Bay)
Status	Retreating

Jakobshavn Isbræ. Also known as the Jakobshavn Glacier or Sermeq Kujalleq, it is a major tidewater glacier located on the west coast of Greenland, near the town of Ilulissat. It is one of the fastest and most productive glaciers in the world, draining approximately 7% of the Greenland ice sheet and calving massive icebergs into the Ilulissat Icefjord, a UNESCO World Heritage Site. The glacier's dramatic acceleration and retreat since the late 1990s have made it a critical focus for studying the impacts of climate change on ice sheet dynamics and global sea level rise.

Overview

Jakobshavn Isbræ originates from the vast Greenland ice sheet, flowing westward into the Ilulissat Icefjord and ultimately Disko Bay, an inlet of the Baffin Bay. The glacier has been a significant feature for centuries, with its calving front historically serving as the presumed source of the iceberg that sank the RMS Titanic in 1912. The surrounding area, including the Ilulissat Icefjord, was designated a UNESCO World Heritage Site in 2004 due to its spectacular natural phenomena and importance for understanding glaciology. The glacier's behavior is a key indicator of the health of the Greenland ice sheet and is intensively monitored by organizations like NASA and the Geological Survey of Denmark and Greenland.

Physical characteristics

As a major outlet glacier, Jakobshavn Isbræ features a deep, fast-flowing ice stream that reaches thicknesses of nearly 2,000 meters. Its bed topography, mapped by missions like Operation IceBridge, shows a deep, retrograde trough below sea level that extends far inland, making it particularly vulnerable to warm ocean currents. The glacier terminates in a floating ice tongue that extends into the Ilulissat Icefjord before calving. The fjord itself is often clogged with a mélange of icebergs and sea ice, which can temporarily buttress the glacier's flow. The ice produced is some of the hardest and oldest in Greenland, originating from the interior accumulation zones of the ice sheet.

Recent changes and retreat

Since the late 1990s, Jakobshavn Isbræ has undergone one of the most dramatic transformations observed on Earth. The glacier doubled its flow speed between 1997 and 2003, coinciding with the rapid disintegration and loss of its floating ice tongue. This acceleration is strongly linked to the influx of warmer waters from the Atlantic Ocean, specifically a branch of the Irminger Current, which has increased submarine melt at the calving front. The retreat has been non-linear, with periods of rapid retreat followed by brief stabilization, but the overall trend since the Little Ice Age maximum has been one of significant recession. Events like the loss of a massive iceberg in 2010 highlight its ongoing instability.

Impact on sea level rise

Jakobshavn Isbræ is the single largest contributor to sea level rise from the Greenland ice sheet. Its accelerated discharge of ice into the Atlantic Ocean accounts for a significant portion of the ice sheet's total mass loss. Studies using data from GRACE and other satellites estimate that the glacier alone contributed roughly one millimeter to global sea levels between 2000 and 2010. The process of dynamic thinning, where faster flow leads to drawdown of inland ice, is a major concern for projections made by the Intergovernmental Panel on Climate Change. If such behavior spreads to other outlet glaciers like Helheim Glacier or Kangerlussuaq Glacier, the contribution from Greenland could increase substantially.

Scientific research and monitoring

The glacier is a natural laboratory for cryosphere science and is monitored by a vast international effort. Key research programs include NASA's Operation IceBridge and the Oceans Melting Greenland mission, which study ice thickness, bedrock topography, and ocean interactions. Institutions like the University of Colorado Boulder, the University of Washington, and the Alfred Wegener Institute maintain field camps and deploy autonomous sensors. Long-term data from satellites like Landsat, Terra, and Sentinel-1 provide critical records of velocity and retreat. This research is vital for improving models used by the Intergovernmental Panel on Climate Change to forecast future sea level rise.

Category:Glaciers of Greenland Category:Ilulissat