Ice Sheets and Sea Level Rise – what we know and why it matters
17th July 2025
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.
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.
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.
