Satellite images reveal hidden retreat of Arctic glaciers

The Arctic plays an increasingly important role in global discussions about rising sea levels and the threats they pose to coastal areas around the world.

With this in mind, it is necessary to explore the intricate process of calving – where ice breaks away from a glacier’s edge.

This phenomenon significantly contributes to sea-level rise, which makes it imperative that we understand the process and can use it to predict future changes in our world.

Arctic exploration with Sentinel-1

A recent stride forward in this quest for understanding has been made by a remarkable collaboration between I-SEA (based in France) and NORCE (from Norway).

As part of the Space for Shore project, the scientists have made extensive use of over a thousand images from the Sentinel-1 mission.

Their purpose? To meticulously monitor the evolution of Svalbard’s coastal glaciers.

The Sentinel-1 mission, a key element of the European Union’s Copernicus Program, employed synthetic aperture radar (SAR) technology to capture high-resolution data in the challenging Arctic conditions.

Thanks to this technology, there is now consistent, year-round monitoring of these critical glaciers.

Measuring calving activity

Using Sentinel-1 data between 2015 and 2023, the researchers were able to map glacier front lines and measure calving activity during Svalbard’s summer months, the period when calving intensities peak.

One significant breakthrough was the ability to define the summer glacier fronts.

The researchers examined images taken between July and September and were able to identify summer glacier fronts as areas where glacier extent is maintained 95% of the time during these months.

What’s more, the team found a way to understand summer calving intensity by observing floating icebergs and growlers.

Interestingly, summers with a higher occurrence of these ice masses indicate more active calving and accelerated glacier retreat. These are crucial signs of a glacier’s health and stability.

Observing changes in Arctic glaciers

In Kongsfjorden, one of the primary study areas, glaciers like Kronebreen and Kongsvegen showed significant changes.

Daily Sentinel-1 observations were used to classify the region into areas of glacier, iceberg, and growler occurrence.

The Sentinel-1 method “provides a statistically defined composite of the summer glacier front positions and calving intensities, revealing the dynamic interactions between ice and ocean over time,” explained Jörg Haarpaintner, a team member from NORCE.

Manon Tranchand, the project’s lead researcher, noted that this analysis paints a clear picture of current changes in Arctic glaciers.

“They’re crucial for predicting the future impacts of climate change on these sensitive regions,” said Tranchand.

“Without the consistent, high-resolution data from Sentinel-1, monitoring these dynamic ice-ocean interactions wouldn’t be possible. Ongoing warming is likely to accelerate ice loss, and our data show how that could contribute to global sea-level rise. Sentinel-1’s capabilities allow us to capture these shifts with unprecedented accuracy.”

The launch of Sentinel-1C

Scheduled for launch next month, Sentinel-1C represents a significant leap forward in the monitoring of Arctic glaciers and global climate impacts.

The soon-to-be addition to the Sentinel-1 mission will offer enhanced radar imaging capabilities and improved continuity for crucial climate research.

With its advanced capabilities, Sentinel-1C will amplify our ability to capture detailed, year-round data on glacier front lines, calving rates, and ice-ocean interactions, even amidst the challenging conditions of the Arctic.

Global implications of Arctic ice loss

The insights gained from monitoring Arctic glacier calving extend far beyond the region itself.

As glaciers retreat and calving intensifies, the influx of freshwater into the oceans disrupts natural currents, including the Atlantic Meridional Overturning Circulation (AMOC), a critical component of Earth’s climate system.

This disruption could lead to significant shifts in weather patterns, such as harsher winters in Europe and intensified monsoons in South Asia.

Moreover, Arctic ice loss exacerbates the global feedback loop of climate change. As ice melts, it exposes darker ocean water, which absorbs more sunlight, accelerating warming – a phenomenon known as the albedo effect.

These changes not only impact the Arctic’s fragile ecosystems but also have cascading effects on biodiversity, fisheries, and human livelihoods worldwide.

By understanding the intricacies of glacier calving through missions like Sentinel-1, researchers are equipping policymakers with the tools to anticipate and mitigate these far-reaching impacts.

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