Ice Sheets and Sea Level Rise – what we know and why it matters

Mean sea level has risen by 11.5cm since the early 1990s, due to the melting of land ice, changes in land-water storage (when water originally contained on land mass moves into the oceans) and thermal expansion of the oceans (water expanding as it warms).

Sea level rise is already affecting the UK, increasing coastal erosion and flooding, in particular during storm surges. This puts coastal communities, habitats and key infrastructure, such as power stations, at risk.

Monitoring the Ice Sheets

The Earth’s colossal ice sheets, in Greenland and Antarctica, are major contributors to sea level rise.

Thanks to advancements in Earth Observation satellite missions, technologies and computer modelling capabilities, we can now monitor these ice sheets accurately and project future scenarios. However, significant uncertainties remain around how the ice sheets are going to behave in the coming decades.

Insights from the Experts

In the ‘Sea Level Uncertainties From the Ice Sheets’ webinar (16 July) organised by the UK National Climate Science Partnership, Dr Inès Otosaka (CPOM) and Dr Rosie Williams from the British Antarctic Survey (BAS) shared key findings.

Ice sheets are melting, and this is accelerating

Dr Otosaka explained:

• The Ice Sheet Mass Balance Inter-Comparison Exercise (IMBIE) led by CPOM has been utilising data from satellite missions to monitor the mass balance of the ice sheets and their contribution to sea levels.
• The Greenland and Antarctic ice sheets are contributing a quarter of all sea level rise and are driving its acceleration. Since 1979, ice sheets have added 3.2cm to sea level rise and the pace of loss is increasing.
• Greenland is melting faster than Antarctica now, but Antarctica is seeing mass loss in the West.
• Ice loss is tracking at the upper end of IPCC projections.

Why so much uncertainty?

Dr Williams explained that:

• Different models and climate forcings produce varying results.
• Subsurface processes such as under-ice melting are hard to observe from space.
• Smaller scale processes can have large impacts, for instance calving and fracturing of the ice sheet as they are taking place at inaccessible places and no laws around general calving currently exist.
• Instability processes such as Marine Ice Cliff Instability (MICI) are still not fully understood.

Rosie went on to explain some of the High Impact Low Likelihood (HILL) scenarios produced by the IPCC.

• The contribution of Antarctic ice melt will dominate all other sources of sea level rise in the coming years due to Marine Ice Cliff Instability.
• By 2100 we could see almost 2m of sea level rise.

The cost of inaction

The UK, and many other countries around the world, are vulnerable to the impacts of sea level rise, so we need to understand better what’s coming and when.

If we fail to adapt appropriately to sea level rise by 2050 the cost could exceed £24 billion a year, in comparison to the projected cost of £3.41 billion/year for ideal adaptation (Rising et al., 2022).

It is vital we understand the potential scenarios and can recognise when we are confronted with one. This is why there is an urgent need to continue to monitor and model the ice sheets.

What we can do

Despite the risks, there is still hope. The worst-case scenarios are not inevitable. Research conducted by the TerraFIRMA team using the UK Earth System Model (UKESM) simulations shows that every degree of warming matters when it comes to sea level rise.

If we act now to reduce emissions, boost our capabilities in monitoring and modelling the ice, and develop Early Warning Systems, we can still aim to thrive in a changing climate.

Watch the full presentation to find out more…

On Wednesday at the European Space Agency’s Living Planet Symposium 2025 we had a fantastic celebration of a very special satellite mission: CryoSat.

CryoSat-2 is very close to our hearts here at the UK Centre for Observation and Modelling (CPOM), due to the crucial role the intrepid Earth Explorer plays in gathering data on the Earth’s ice sheets, sea ice, ice shelves and glaciers. Without this information, we wouldn’t have made the significant leaps forward in polar and climate science over the last two decades.

In the session ‘Celebrating 15 Years of CryoSat for climate science’ led by Tommaso Parrinello (Aeolus and CryoSat Mission Manager, ESA) we heard from a range of scientists on the importance of this mission and how it has contributed to our understanding of the cryosphere, its impact on the wider Earth systems and sea level rise, as well as how it will continue to shape the future of climate science.

To mark this special occasion, we have put together this list of 10 cool things we love about CryoSat-2 from yesterday’s fascinating series of talks on the mission.

1. The idea for CryoSat was conceived by Sir Duncan Wingham, CPOM’s founding Director, but the first satellite was lost in a launch failure in 2005. Thankfully it was rebuilt and launched successfully five years later in 2010.
2. CryoSat’s original mission objectives were to monitor polar ice sheets and arctic sea ice, but today a large proportion of scientific papers using CryoSat data is on topics outside of the cryosphere, noted Andrew Shepherd in his presentation.
3. CryoSat has been instrumental in monitoring global ice losses! In 2021 a study led by CPOM’s Tom Slater showed that Earth is losing 1 trillion tonnes of ice each year. The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) Project led by CPOM’s Inès Otosaka now produces annual assessments of ice sheet mass balance, taking advantage of CryoSat data alongside other satellite missions.
4. CryoSat even works on Canadian ice caps, said Professor Rene Forsberg! CryoSat can capture information on smaller ice caps and glaciers due to the advancement of the swath processing technique. Swath processing uses interferometry to map ‘broad swaths of surface elevation’ allowing for higher resolution (less than one kilometre) elevation measurements.
5. In 2023, CryoSat went global on glaciers! The first global assessment of global glacier mass change with radar altimetry was produced (Jakob & Gourmelen, 2023). This year the GLAMBIE project produced updated figures on glacier loss showing that from 2000 – 2023 glaciers across the globe lost 6542 billion tonnes of ice, contributing 18 mm to global sea level rise.
6. CryoSat-2 and ICESat-2 are complementary! A recent study led by CPOM’s Nitin Ravinder showed that CryoSat and ICESat-2 measured Greenland ice sheet elevation change measurements agree with each other to within 3%, confirming that results from these satellites can be combined to produce a more reliable view of ice sheets.
7. There is a CryoTEMPO product suite which uses CryoSat-2 data to produce easily accessible, user-friendly data products for a variety of thematic areas such as sea ice, land ice, polar oceans, coastal oceans and inland water.
8. CryoSat provides insights on sea level rise. Anny Cazenave (LEGOS) gave a wonderful overview on how CryoSat-2 has supported our understanding of sea level rise, sharing insights on altimetry-based sea level trends (2011-2022) AVISO.
9. Dr Livia Jakob (Earthwave) introduced us to the CryoSat Companion now available through ChatGPT! This new AI assistant supports people in using and understanding the data. It even told us an icy joke during the presentation.
10. CryoSat is inspiration of the new CRISTAL mission due to launch in 2027. Set to be a considerable advancement for polar science due to it’s dual-frequency Interferometric Radar altimeter for Ice and Snow (IRIS).

But this is just the tip of the iceberg (sorry!). There’s still so much to learn from CryoSat, and you can do that by following updates from @esa_cryosat on X.

CryoSat’s journey is not over yet, by any means!

In the session ‘Outlook for ESA’s Earth Observation programmes’ at the European Space Agency’s Living Planet Symposium 2025, we heard from Josef Aschbacher, Director General of European Space Agency – ESA, Simonetta Cheli – Director of Earth Observation at ESA, Charles Galland, Policy Manager at ASD-Eurospace, and Andrew Shepherd, CPOM Director (Northumbria University) on the planned funding proposal to EU Member States due later this year. Andrew stood as a representative of the scientific community due to his long-standing collaborative relationship with the European Space Agency and over two decades of experience of EO scientific research.

Josef Aschbacher said: “We are delivering data and services for citizens. Earth Observation is providing a lot of this: services for farmers, for health practitioners, for city planners, for forestry, for aviation, for disaster management to provide information in case of crises.”

Simonetta Cheli said: “There’s an increase of the relevance of space in support of resilience, in support of security, in support of defence needs, and there is also a geopolitical context where EO could provide a further opportunity to increase overall, not just at ESA level, the European leading role that we have in the sector on climate, on sustainability, and the current proposal is a really bold step in that direction.”

Charles Galland said: “This is a strategic investment in Europe’s industrial future. ESA must remain a scientific and technical leader but also increasingly become an economic and market enabler. Industry is ready for that.”

Andrew Shepherd said: “The science is what underpins action, by other people or by ourselves to address the problems the climate is facing and to adapt to the world that we are going to be living in.”

Andrew’s presentation highlighted that:

🌐 Climate science is founded on EO
🛰️ Science underpins action
🌳 Action is the green economy
🌍 Europe is leading the way
🚀 FutureEO is essential

This fascinating session was part of the Living Planet Symposium 2025.

🔗 For the full schedule visit: https://lps25.esa.int/

The UK Centre for Polar Observation (CPOM) is presenting a range of scientific studies and research this week at the European Space Agency (ESA) Living Planet Symposium in Vienna.

On Monday, CPOM Co-Director for Science, Professor Mal McMillan, presented results from the first phase of the CLEV2ER project, which is designing and building Level-2 processor prototypes for land ice and inland water, supporting the scientific readiness of the Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) ahead of the mission’s operational phase.

But what is CRISTAL?

The European Space Agency (ESA) is currently preparing for the launch of the Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) in 2027. Set to be a considerable advancement for polar science, CRISTAL will be equipped with a dual-frequency Interferometric Radar altimeter for Ice and Snow (IRIS) – a first for a satellite mission – and a passive microwave radiometer. This will give it the capability to monitor ice-sheet elevation as well as sea ice thickness and the overlying snow depth.

The mission is designed with long-term monitoring in mind, with two identical satellites CRISTAL A and CRISTAL B, with B replacing A before its lifespan finishes to ensure continued data collection.

What’s cool about the IRIS altimeter?

IRIS operates at Ku-band (13.5 GHz) and Ka-band (35.75 GHz) frequencies, known as KuKa. Using both frequencies, this radar can measure snow depth and sea ice thickness at the same time. CRISTAL will be able to measure the thickness of sea ice, the snow that covers it and the elevation of the world’s ice sheets and glaciers ensuring improvement and continuity from the CryoSat-2 mission. This information will be further complemented by data from a Microwave Radiometer providing even more precise information on surface-type classification and snow layer properties.

The ability to assess the depth of the snow overlying sea ice will increase the accuracy of sea ice thickness data, with importance for better understanding polar ice dynamics and global climate. Monitoring the height of ice sheets will support studies on ice mass balance and sea level rise attributed to melting ice sheets.

CRISTAL A is currently having components added by Airbus, with the satellite developed initially by ACPO Technologies. Thales Alenia Space is developing the IRIS altimeter, and the microwave radiometer will be provided by NASA’s Jet Propulsion Laboratory. You can read more about CRISTAL on ESA’s website.

CPOM Postdoctoral Researcher Dr Karla Boxall (Lancaster University), will also present an overview of progress on the CLEV2ER project on Wednesday including details on analysis and improvements of the methodology used for uncertainty estimation, the retrieval of penetration depth from dual band altimetry, and the role of snowpack properties on penetration depth estimates.

Dr Karla Boxall said:

“CRISTAL’s advanced multi-frequency altimeter provides an exciting opportunity to measure snow depth and coverage, which will improve quality of sea ice thickness and ice sheet elevation data significantly compared to its predecessor, CryoSat-2. CRISTAL will also play a vital role in ensuring the long-term continuation of radar-derived ice elevation records.”

Working together with emerging technology to prepare for a changing future

It is vital for the scientific community to collaborate and build on existing observation and modelling capabilities to ensure the effective and sustainable use of emerging technologies.

The cryosphere is a critical system of our evolving planet where changes often foreshadow broader impacts across the Earth. Melting ice sheets are contributing to rising sea level, and the influx of cold meltwater is affecting our ocean circulation systems, impacting our weather. Government agencies therefore need comprehensive and timely information to plan effectively.

In recent decades our ability to assess the polar regions has improved significantly due to satellite missions such as ESA’s CryoSat-2 and NASA’s ICESat and ICESat-2, along with advancement of observation and computer modelling techniques used by scientists at CPOM. The development of the CRISTAL space mission, and its enhanced radar altimetry technology, will support governments and agencies across the world prepare for climate change, by providing continuous, accurate Earth Observation data to enhance climate models and their projections of future polar ice behaviour.

• For more updates on CPOM at LPS25 follow us on X, Bluesky, Instagram and LinkedIn.
• For the exciting full LPS25 schedule, visit the LPS website.

Image credit: ESA

The Environmental Audit Committee has released its report on the UK and the Antarctic environment featuring evidence from CPOM and colleagues from across the polar science community.

This inquiry explores the impacts of climate change in Antarctica and the role that UK science can play in understanding these changes and protecting the region.

Our evidence, submitted via two calls for evidence in 2024, highlighted:

• Changes in the Antarctic will have global consequences for people and animals.
• We will need to adapt to significant impacts from sea level rise in the coming years.
• The UK needs to commit to supporting long-term international collaborations between modellers, climate scientists, and remote sensing specialists to ensure we are fully prepared for these changes.
• There is an opportunity to improve observations through the United Nations Antarctica InSync programme.
• There is a requirement for governance of any future geoengineering schemes in the region.

Parliamentary inquiries are an important way academics can inform the UK Government about relevant scientific research and provide advice to influence policy decisions.

The can read the full report and supporting evidence on the UK Parliament website.

To find out more about how CPOM provides information for policymakers on our Research Impact pages.

Web Story Image Credit: Professor Andrew Shepherd

Research published today (Thurs May 8) in the journal The Cryosphere shows one glacier siphoning ice from another in the Pope, Smith and Kohler (PSK) region in West Antarctica.

This phenomenon, termed ‘ice piracy’ was previously thought to only take place over centuries or millennia, however the team of scientists, led by Heather Selley (University of Leeds), used satellite observations from the Copernicus Sentinel-1 and CryoSat-2 missions, among others, to show that a faster-flowing Kohler East Glacier has been ‘stealing’ ice from a slower neighbour over the last 18 years.

Measuring the displacement of crevasses or rifts the team was able to calculate ice velocity, and through this they discovered that most ice flows from the glaciers had sped up, but that one had slowed down. The research also identified changes in the direction of flow which they believe led to the Kohler East Glacier siphoning the ice from Kohler West Glacier.

This discovery helps improve understanding of ice dynamics in the Antarctic and how ice melt there is contributing to sea level rise.

The paper ‘Speed-up, slowdown, and redirection of ice flow on neighbouring ice streams in the Pope, Smith and Kohler region of West Antarctica’ was published in The Cryosphere on Thursday May 8, 2025.

The research was a collaboration led by Leeds, with researchers from the British Antarctic Survey (BAS) and the UK Centre for Polar Observation and Modelling (CPOM) which is led from Northumbria University, using data provided by satellites belonging to the European Space Agency (ESA), Japan Aerospace Exploration Agency, Canadian Space Agency and NASA.

It was funded by UKRI Natural Environment Research Council (NERC), the Science for Society element of ESA’s FutureEO programme and NASA Headquarters.

Read more on the University of Leeds website and the ESA website.

Image Credit: British Antarctic Survey (BAS).

National Capability is long-term, strategic science spanning decades, which enables the development of exciting step changes in techniques and technologies. The ongoing development and maintenance of these capabilities makes a much wider portfolio of environmental science possible.

The UK Polar Research Expertise for Science and Society (PRESCIENT), a British Antarctic Survey (BAS)/CPOM partnership, provides the UK and wider scientific community with the necessary infrastructure and data to support research into the polar regions. Through PRESCIENT, scientists provide essential advice to Government to inform policy and help prepare for the effects of climate-related changes.

In this first annual meeting of PRESCIENT, introduced by Professor Dominic Hodgson, interim Director of Science at BAS, and Professor Andrew Shepherd, CPOM Director, we heard from scientists across the programme on exciting advances and achievements in polar climate data records, long-term observations of ecosystems in regions of the Southern Ocean, sea-level Rise science and the Space Weather Observatory.

We also heard from Sophie Hodgson (Associate Director for National Capability, NERC) about the importance of National Capability to UK science and research: “you can’t understand trends and what is happening in the world if they’re not being observed over long periods of time.”

This broad programme of work supports and underpins research into how environmental change is affecting the polar regions, how this in turn leads to global sea-level rise, and space weather impacts measured from Antarctica.

The PRESCIENT programme is funded by NERC’s National Capability Single Centre Science and National Public Good initiatives.

You can read more about this Programme on the British Antarctic Survey website.

CryoSat-2 was successfully launched by the European Space Agency fifteen years ago today on 8th April 2010.

To mark the day, we’ve put together this short history of CryoSat-2 and how this fantastic satellite mission has contributed to polar science.

The original CryoSat-1 mission was proposed by CPOM’s Founder, Sir Duncan Wingham, in 1998 and launched in 2005; however, a programming issue with the rocket meant that this satellite was lost immediately after launch.

Its successor, CryoSat-2 was launched in in 2010 with CPOM Director Andy Shepherd as the mission’s Principal Scientific Advisor. CryoSat-2 was designed to last approximately 5 years, but it is still in orbit today and the mission has now been extended until 2028.

CryoSat-2 uses a radar instrument called SIRAL (Synthetic Aperture Interferometric Radar Altimeter), designed to measure Earth’s land and sea ice. It can measure changes at the margins of vast ice sheets and floating ice in polar oceans. SIRAL can not only detect tiny variations in the height of the ice but also measure sea level with unprecedented accuracy.

Here are just some of the ways CPOM has used CryoSat data in the last fifteen years:

Monitoring ice sheet mass balance

The CPOM-led IMBIE Project (Ice Sheet Mass Balance Intercomparison Project) provides a long-term record of polar ice sheet melting in Greenland and Antarctica from community submitted estimates derived from satellite observations. Taking advantage of data from missions including CryoSat-2, IMBIE has made it possible to chart polar ice sheet mass change every year, ensuring the scientific community has the very latest estimates.

Understand the dynamics of sea ice

This recent research led by CPOM Associate Investigator Harry Heorton, uses the “consistent, good coverage” sea ice thickness data from CryoSat-2 to give an estimate of sea ice volume from 2010 – 2022. Take a look at this ESA article to find out more.

Detecting changes in the subglacial lakes

Led by CPOM Associate Investigator Noel Gourmelen (The University of Edinburgh & Earthwave), this research on sudden drainage events of subglacial lakes uses European Space Agency – ESA CryoSat-2 data, combined with computer models of glacier flow and ocean currents through the ESA FutureEO Science for Society 4D Antarctica project.

Improving climate models

Data from CryoSat-2, and other Earth observation missions, helps scientists to project future changes to the Earth’s ice and its impact on sea level rise by providing boundary conditions for numerical models and improving understanding of key ice loss mechanisms. CryoSat-2 data has been used in simulations from computer models such as BISICLES , which has been integrated into the UK Earth System Model (UKESM) as well as used in the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6).

Visit the CPOM data portal to see CryoSat measurements of sea ice, ice sheets, ice shelves and ice velocity.

Image credit: ESA / AOES Medialab

Here at the UK Centre for Polar Observation and Modelling, we love spreading the word about our science, but also about the wider world of Earth Observation and modelling, satellites, net zero science and more. That’s why we regularly write blogs and articles about interesting research and findings, to raise awareness about the polar regions and the vital information being collected by satellites like ICESat-2 and CryoSat-2.

Whether you’re a scientist already working in the field, are thinking about studying science, or just love learning about space, satellites and the polar regions, there are a number of ways you can keep up to date with news and stories from CPOM:

Follow us on social media

We regular post our articles and repost interesting information from our colleagues in the field on our social media channels.

We are currently on the following platforms:

LinkedIn
Instagram
Threads
Bluesky
X (formerly Twitter)

We would love to hear from you, so do please comment on our posts if you have any questions you would like to ask about our science.

Join us at an event

We regularly attend a range of events, from scientific and academic conferences to family-friendly events, like the Festival of Tomorrow, where we had an activity stand at the end of February. We advertise these events on social media, but also here on our website, so do come along if you see one advertised in your area. We would love to meet you!

Get in touch directly!

We would love to hear from you! Get in touch with us if you would like to find out more about our work or think we could work together in the future.

Have you heard about the colossal A23a iceberg, currently grounded off the coast of the South Atlantic island of South Georgia?

This iceberg first broke away in 1986 and remained on a sandbank in the middle of the Weddell Sea for 35 years.

Scientists from the UK Centre for Polar Observation and Modelling (CPOM) monitor icebergs like A23a from space using satellites to better understand the impact of a warming climate on the cryosphere.

Recently, A23a has been making headlines as it drifts closer to South Georgia, raising concerns about its potential effects on shipping routes and local wildlife.

Over the weekend (14 – 15 March 2025), CPOM Director Professor Andrew Shepherd spoke to Sky News and Times Radio about this iceberg and the threats it poses to penguins, seals, and marine life that thrive in these coastal areas.

You can find his interview in Saturday’s Times Radio Breakfast programme (56 minutes in).

As we don’t get to see these icebergs up close very often, it is fantastic to see this video footage from Sky News, which helps show the true scale of this mega iceberg.

Image Credit: Professor Andrew Shepherd (taken in Antarctica).