Sentinel-1’s decade of essential data over shifting ice sheets

The mission’s observations now span a decade, starting in 2014, and provide the first continuous, high-resolution record of the ice-flow velocities across the Greenland and Antarctica ice sheets.

This long-term dataset, published as a study in Remote Sensing of Environment journal, is based on advanced processing of radar data from Sentinel-1’s synthetic aperture radar (SAR) instrument. The study is part of a collection of academic papers curated by ESA to mark the 10-year anniversary of the Sentinel-1 mission. The special issue underlines the importance of long-term and high-resolution datasets for many applications, including monitoring the changes in ice sheets in Greenland and the Antarctic.

Ice velocity on Antarctica

The data visualisation of Antarctica (see image on the left) shows details of ice flows moving at speeds between 1 m and 15 m per day. The Sentinel-1 data is averaged over the period 2014–2024. Regions shown on the map include the Antarctic Peninsula and Alexander Island, as well as large parts of the West Antarctic Ice Sheet and East Antarctic Ice Sheet. Most of the coastal areas were captured at either six or 12-day intervals.

On the West Antarctic Ice Sheet (on the left of the image), the Pine Island Glacier is clearly visible below the Antarctic Peninsula. Over the period of the study, the velocity of ice flow at the glacier’s grounding line – the point where grounded ice detaches from the bedrock underneath it and becomes a floating ice shelf – increased continuously from approximately 10.6 m per day to 12.7 m per day. Other nearby glaciers also showed increased ice flow. These changes are caused by a range of factors including ocean-induced thinning of the floating ice shelves combined with a retreat of the grounding line.

Greenland’s ice flows

The study shows the rapid flow of ice, moving at average speeds of up to 15 m per day, from glaciers and ice sheets at points around the Greenland Ice Sheet (see image on the right). Half-way up the western coast of Greenland, Sermeq Kujalleq, also known as the Jakobshavn Glacier, is one of the fastest outlet glaciers in the world with velocities reaching, at times, as much as 50 m per day (see a zoomed-in map below).

The North-East Greenland Ice Stream (NEGIS), is also clearly visible on the Greenland Ice Sheet and begins far inland at the ‘ice divide’, shown as a dark blue band of nearly stagnant ice in Greenland’s interior.

The dataset offers unprecedented spatial detail, with resolution up to 200–250 m, as well as timeframes for tracking movement ranging from less than a week to more than a decade.

Mapping the effects of climate change

Ice velocity is a key parameter in measuring the effects of climate change. The speed at which glaciers and ice sheets move tells us the rate at which they discharge ice and water into the sea, feeding into estimations on future sea-level rise. Data on ice velocity also help to keep track of the break-up of ice sheets, such as calving events or damage to the ice sheets.

Strengthening the ability to monitor ice dynamics is vital for refining predictions of future changes in ice sheets and glaciers, their impact on sea-level rise, and their broader effects on the climate.

Lead-author of the study, Jan Wuite, of ENVEO IT, noted the impact made by the Copernicus Sentinel-1 mission to monitoring ice flow movements. He said, “Before the launch of Sentinel-1, the absence of consistent SAR observations over polar glaciers and ice sheets posed a major barrier to long-term climate records. Today, the resulting velocity maps offer an extraordinary view of ice-sheet dynamics, providing a reliable and essential data record for understanding polar regions in a rapidly changing global climate.”

The annual ice velocity products for Greenland and Antarctica are operationally generated within the Copernicus Climate Change Service (C3S) for the cryosphere domain, which is led by ENVEO. Joaquín Muñoz Sabater, the responsible scientist at the European Centre for Medium-Range Weather Forecasts (ECMWF) for the C3S cryosphere service, stated, “The ice velocity time series for Antarctica and Greenland are an essential component of the C3S Cryosphere Service and a key contribution to monitoring the impacts of global warming in some of the world’s most sensitive regions.”

Step change in polar observation

Since its first satellite was launched in 2014, the Copernicus Sentinel-1 mission has provided a step change in the capabilities of polar satellite Earth observation. Its 12-m-long advanced SAR instrument works in C-band. This makes it a reliable tool for acquiring high-resolution imagery for continuous monitoring and emergency response efforts. It is able to capture data through cloud cover, smoke and during lack of sunlight

Nuno Miranda, ESA’s Sentinel-1 Mission Manager, explained, “Before Sentinel-1, generating such results required combining data from multiple sensors over several years. With Sentinel-1, these results are now produced annually and, thanks to advances in science, even monthly. This breakthrough enables monitoring of these remote areas with unprecedented temporal resolution. It is an essential tool as 2025 marks another record-breaking year of Arctic warming, where rapid changes demand closer and more frequent observation.”

The mission has enabled, for the first time, the generation of large-scale, dense and continuous time series of polar ice velocity for climate research. The mission has also enabled the application of Interferometry SAR (InSAR) for ice velocity retrieval on larger scales than before. It provides a systematic acquisition strategy for the polar regions, which ensures continuous coverage of the main sectors of the Greenland and Antarctic ice sheets, as well as of other ice masses.

With the launch of the mission’s fourth satellite – Sentinel-1D – at the end of 2025, the mission’s capacity to provide regular acquisitions every six days or less over Greenland and Antarctica is restored. This reinstates and even enhances the capabilities that existed before the breakdown of Sentinel-1B.

Using the extensive Sentinel-1 SAR archive, the authors of the study developed algorithms to generate detailed maps and dense time series of glacier and ice sheet velocity now spanning more than 10 years. The study’s results show Sentinel-1’s exceptional ability to comprehensively monitor flow velocities on glaciers and ice sheets, providing crucial data for ice dynamics and climate modelling

Why does it matter?

The rise of global sea levels depends on two main contributing factors, according to data from the World Meteorological Organization. These two factors are the expansion of warming water in the oceans and meltwater from ice on land. The Antarctic and Greenland ice sheets are the main sources of meltwater from ice on land; together they hold enough ice to raise global sea levels catastrophically if they were to melt entirely. Current ice mass loss is already affecting coastal regions worldwide, including low-lying areas vulnerable to flooding and storm surges.

This study underscores how satellites are essential to understanding and forecasting the evolving risk from ice sheet loss. It is the first time that scientists have established a consistent, continent-wide baseline of how the ice of Greenland and Antarctica moves under recent conditions. That baseline will help detect future acceleration, or any deceleration, of ice flow.

Looking ahead to collaboration

In future, data from Sentinel-1 will be used with SAR data from the upcoming Copernicus expansion mission ROSE-L. This will ensure systematic, continuous acquisitions over Greenland and Antarctica well into the future.

CEO of ENVEO IT, Thomas Nagler, also a co-author on the study, added, “Sentinel-1 revolutionised our view of polar ice sheets by providing continuous, weather-independent radar measurements that reveal ice motion in unprecedented detail, transforming ice flow from a sparse snapshot into a dynamic, measurable process. Building on this legacy, the integration of Sentinel-1 with the upcoming ROSE-L mission will further improve ice-flow observations, enabling more accurate and stable monitoring of ice-sheet dynamics.”