Columbia Glacier on the south coast of Alaska

Today’s Image of the Day from the European Space Agency features the Columbia Glacier, a tidewater glacier located in Prince William Sound on the south coast of Alaska.

It is one of the most rapidly changing glaciers in the world and has been closely studied for the insights it provides into glacial mechanics and climate change impacts. 

“Since the early 1980s, the Columbia Glacier has retreated more than 20 km and lost about half of its total volume. This one glacier accounts for nearly half of the ice lost in the Chugach Mountains,” noted ESA.

“The changing climate is thought to have caused its retreat. Until 1980, when its rapid and constant retreat began, the glacier’s terminus was observed at the northern edge of Heather Island, which lies near the end of Columbia Bay, the inlet into which the glacier currently flows before draining into Prince William Sound.”

“This satellite image, acquired in September 2023, shows instead the deep mostly ice-free Columbia Bay dotted with numerous icebergs and fragmented sea-ice.”

Dramatic calving events

The Columbia Glacier is known for its dramatic calving events, where large chunks of ice break off from the glacier’s terminus and fall into the sea, becoming icebergs. This process has been particularly active as the glacier has retreated, contributing to hazards for shipping in Prince William Sound.

The glacier has been the focus of extensive scientific research, serving as a case study for understanding the dynamics of tidewater glaciers and their responses to climate change. Studies have used satellite imagery, field observations, and modeling to track its changes over time.

Climate impact on the Columbia Glacier

“Columbia is just one of the many glaciers suffering from the effects of climate change. Most of the glaciers around the world are losing mass. However, before the advent of satellites, measuring their retreat and studying their vulnerability to climate change was difficult considering their size, remoteness and rugged terrain they occupy,” said ESA.

“Different satellite instruments now can gather information systematically and over large areas, providing an effective means to monitor change, keep track of all calving stages and quantify the melting rate and their contribution to sea-level rise.”

More about Columbia Glacier 

Columbia Glacier flows from the Chugach Mountains into Columbia Bay. It was once one of the largest contributors to sea level rise due to its significant ice loss. 

The glacier’s dynamics are influenced by its interaction with water, where the terminus meets the ocean. As the glacier flows into the sea, large chunks of ice calve off the front, leading to dramatic scenes of ice crashing into the ocean. This process has been intensifying due to warmer temperatures and changes in water circulation, which undermine the ice from below.

Columbia Glacier’s retreat has significant implications for marine navigation and local ecosystems. The increase in icebergs calving into the bay poses hazards to ships, while the fresh meltwater impacts local water temperatures and salinity, affecting the habitat of fish and other marine life.

Melting glaciers and ocean composition 

Glaciers, which are large masses of accumulated snow and ice, store about 69 percent of the world’s freshwater. As the climate warms, these glaciers increasingly melt and release freshwater into nearby seas and the ocean at large.

Influx of freshwater

The influx of freshwater from melting glaciers alters the salinity (salt concentration) of the ocean water. Since freshwater is less dense than saltwater, its addition can lead to stratification in which lighter, less salty water layers on top of denser, saltier water. 

Stratification can disrupt ocean currents, which are driven in part by differences in water density and temperature. These currents are crucial for regulating global climate by distributing heat and nutrients around the planet.

Changes in salinity 

Furthermore, changes in salinity can affect marine life, which often has narrow salinity tolerance ranges. For example, shifts in salinity can impact breeding cycles, migration patterns, and the availability of nutrients. 

Global carbon cycle

As the ocean’s composition changes, its capacity to absorb carbon dioxide from the atmosphere could also be altered, affecting the global carbon cycle and, by extension, climate change feedback mechanisms.

The melting of glaciers contributes to more pronounced changes in ocean conditions, impacting everything from global climate systems to local ecosystems in marine environments.

Image Credit: ESA 

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