ESA and NASA satellites deliver first joint picture of Greenland Ice Sheet melting

ESA and NASA satellites deliver first joint picture of Greenland Ice Sheet melting

Story published by The European Space Agency

Global warming is driving the rapid melting of the Greenland Ice Sheet, contributing to global sea level rise and disrupting weather patterns worldwide. Because of this, precise measurements of its changing shape are of critical importance for adapting to climate change.

Now, scientists from the UK Centre for Polar Observation and Modelling have delivered the first measurements of the Greenland Ice Sheet’s changing shape using data from ESA’s CryoSat and NASA’s ICESat-2 ice missions.

Although both satellites carry altimeters as their primary sensor, they make use of different technologies to collect their measurements. CryoSat uses a radar system to determine Earth’s surface height, while ICESat-2 uses a laser system for the same task.

Although radar signals can pass through clouds, they also penetrate the ice sheet surface and have to be adjusted to compensate for this effect. Laser signals, on the other hand, reflect from the actual surface but cannot record when clouds are present. The missions are therefore highly complementary, and combining their measurements has been a holy grail for polar science.

A new study from scientists at the CPOM and published today in Geophysical Research Letters, shows that CryoSat and ICESat-2 measurements of Greenland Ice Sheet elevation change agree to within 3% of the changes taking place.

This confirms that both satellites can be combined to produce a more reliable estimate of ice loss than either could achieve alone. It also means that if one mission were to fail, the other could be relied upon to maintain our record of polar ice change.

Between 2010 and 2023, the Greenland Ice Sheet thinned by 1.2 m on average. However, much larger changes occurred across the ice sheet’s ablation zone where summer melting exceeds winter snowfall; there, the average thinning amounted to 6.4 m.

Image credit: Professor Andrew Shepherd (Northumbria University)

The most extreme thinning occurred at the ice sheets outlet glaciers. At Sermeq Kujalleq in west central Greenland (also known as Jakobshavn Isbræ), the peak thinning was 67 m, and Zachariae Isstrøm in the northeast the peak thinning was 75 m.

Altogether, the ice sheet shrank by 2347 cubic kilometres across the 13-year survey period – similar to the amount of water stored in Africa’s Lake Victoria. The biggest changes occurred in 2012 and 2019, when the ice sheet shrank by more than 400 cubic kilometres because of extreme melting in those years.

Greenland’s ice melting also has profound effects on global ocean circulation and weather patterns. These changes have far-reaching impacts on ecosystems and communities worldwide. The availability of accurate, up-to-date data on ice sheet changes will be critical in helping us to prepare for and adapt to the impacts of climate change.

“We are very excited to have discovered that CryoSat and ICESat-2 are in such close agreement,” says lead author and CPOM researcher Nitin Ravinder. “Their complementary nature provides a strong motivation to combine the data sets to produce improved estimates of ice sheet volume and mass changes. As ice sheet mass loss is a key contributor to global sea level rise, this is incredibly useful for the scientific community and policymakers.”

The study made use of four years of measurements from both missions, including those collected during the Cryo2ice campaign, a pioneering ESA-NASA partnership initiated in 2020. By adjusting CryoSat’s orbit to synchronise with ICESat-2, ESA enabled the near-simultaneous collection of radar and laser data over the same regions.

This alignment allows scientists to measure snow depth from space, offering unprecedented accuracy in tracking sea and land ice thickness.

Credit: ESA

Tommaso Parrinello, CryoSat Mission Manager at ESA, expressed optimism about the campaign’s impact: “CryoSat has provided an invaluable platform for understanding our planet’s ice coverage over the past 14 years, but by aligning our data with ICESat-2, we’ve opened new avenues for precision and insight.

CryoSat Image Credit: European Space Agency

“This collaboration represents an exciting step forward, not just in terms of technology but in how we can better serve scientists and policymakers who rely on our data to understand and mitigate climate impacts.”

“It is great to see that the data from ‘sister missions’ are providing a consistent picture of the changes going on in Greenland,” says Thorsten Markus, project scientist for the ICESat-2 mission at NASA.

“Understanding the similarities and differences between radar and lidar ice sheet height measurements allow us to fully exploit the complementary nature of those satellite missions. Studies like this are critical to put a comprehensive time series of the ICESat, CryoSat-2, ICESat-2, and, in the future, CRISTAL missions together.”

ESA’s CryoSat continues to be instrumental in our understanding of climate related changes in polar ice, working alongside NASA’s ICESat-2 to provide robust, accurate data on ice sheet changes. Together, these missions represent a significant step forward in monitoring polar ice loss and preparing for its global consequences.

For more information, contact the lead author: Nitin Ravinder (n.ravinder@northumbria.ac.uk)

Planning for rapid and irreversible change in the future: CPOM awarded funding to investigate critical climate tipping points in Antarctica

The UK Centre for Polar Observation and Modelling (CPOM) has been awarded over £400,000 by the European Space Agency (ESA) to investigate tipping points in the Earth’s icy regions (the cryosphere), with a focus on the Antarctic.

Climate tipping points are critical thresholds that if crossed, can lead to rapid and irreversible changes in the climate system with dramatic consequences for our society. Crossing these points in the cryosphere has the potential to lead to much faster sea level rise as well as trigger other tipping points in the climate system, therefore it is of vital importance that scientists assess and attempt to understand where and when these tipping points might be crossed. This knowledge will help governments better prepare for the consequences of climate warming.

CPOM Co-Director for Science, Dr Inès Otosaka (Northumbria University) will be leading the ‘CryoTipping’ project with a team of Earth Observation experts from ESA’s Antarctic CCI+ Project and ice sheet modelling experts from Northumbria’s Future of Ice on Earth Peak of Research Excellence.

The research will build on datasets developed by ESA’s Antarctic CCI+ Project, and will combine Earth Observation and numerical modelling to detect marine ice sheet instability in the Amundsen Sea Sector, with a focus on Thwaites glacier.

Dr Otosaka said:

“Satellite observations have shown that the ice sheets have been melting more rapidly than previously thought whilst numerical models have demonstrated their sensitivity to future changes in their surrounding atmosphere and ocean. By combining state-of-the-art satellite observations and numerical modelling techniques, this exciting project will further our understanding of the trigger of instability mechanisms in Antarctica.”

Exploring the potential of using satellite data to detect early warning signs of marine ice sheet instability, the CryoTipping project will be the first to contrast present-day retreat rates of the Thwaites glacier measured from satellite data against those modelled over the past 20,000 years.

Dr Anna Maria Trofaier, Cryosphere Scientist at ESA (European Space Agency) said:

“That Thwaites Glacier is extremely vulnerable to climate change is known. The worry is that ongoing changes could result in a switch to a new state of the West Antarctic Ice Sheet with crucial consequences for sea level rise. If we want to understand the state of this tipping element we need to combine models with observations, and the European Space Agency’s satellite Earth Observation data are ideally placed to support this new project and its important work.”

The team aims to develop a new method to detect these tipping points by feeding satellite observations of grounding line location (where glaciers and ice shelves start to float), ice velocity, and surface elevation changes to an ice sheet model, investigating the onset and potential irreversibility of the retreat of Thwaites glacier over the coming centuries.

The project, funded by ESA and due to commence in early 2025, is led by CPOM (based at Northumbria University), in partnership with ice sheet modelling experts from Northumbria’s Future of Ice on Earth Peak of Research Excellence, PIK (Potsdam Institute for Climate Impact Research) and MPI-GEA (Max Planck Institute of Geoanthropology), and Earth Observation experts from ENVEO IT GmbH and DLR German Aerospace Center.

CPOM is a partnership of six universities and the British Antarctic Survey (BAS), based at Northumbria University, primarily funded by the National Environment Research Council (NERC) to provide national capability in observation and modelling of the processes that occur in the Polar regions of the Earth.

CPOM uses satellite observations to monitor change in the Polar regions and numerical models to better predict how their ice and oceans might evolve in the future. By providing long-term capabilities to the scientific community and leading international assessments, CPOM helps global policymakers plan for the effects of climate change and sea level rise.

Image credit: Andrew Shepherd

Recent research from CPOM and BAS shows record low Antarctic sea ice is four times more likely with climate change

Last year (2023) winter Antarctic sea ice measured at its lowest since 1978 when satellite records began.

Using the CMIP6 data set (climate dataset), British Antarctic Survey (BAS) and Centre for Polar Observation and Modelling (CPOM) researchers investigated this sea ice loss, including data from 18 different climate models in order to understand the likelihood of this level of sea ice loss, and its relationship to climate change.

The research, led by Rachel Diamond (Cambridge University/BAS) shows that this type of event would be a one- in-a-2000-year event without climate change. Using the most up-to-date models showed that this type of decline in sea is four times more likely (a one-in-a-500 year event), suggesting that climate change played a significant role, however this type of event still remains unlikely.

The paper by Diamond, R., et al was published on Monday 20 May 2024 in the journal Geophysical Research Letters.

CPOM Iceland Fieldwork Adventure

In September 2024 a team of CPOM PhD Researchers and staff used drones to study proglacial lakes in Iceland.

While there, they captured their work on camera so we can experience it too.

You can also read about this campaign in more detail on the European Space Agency (ESA) Blog.