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Observing and modelling the Greenland ice sheet with CPOM

5th February 2025

Greenland is a fascinating and beautiful country, with a population of more than 50,000 people. It has long been a key area of focus for polar scientists, due to the importance of observing and modelling of changes to the Greenland ice sheet. This huge expanse of ice, the second largest land ice mass in the world, is more than 2000km in length, 1000km wide and at its thickest point is over 3km thick.

And this ice sheet is melting.

Melting ice sheets directly contribute water to the oceans, leading to sea level rise. This influx of cooler water also affects the ocean circulation, with implications for global weather patterns. Accurately tracking melting of the Greenland and Antarctic ice sheets is essential to ensure people all over the world can prepare for the effects of climate change.

As ice sheets are so huge they are incredibly difficult to fully measure in person. Satellite measurements are the only ways we can accurately measure these vast areas.

CPOM has provided assessments of the amount of ice stored in the Greenland and Antarctic ice sheets since 2018, via the IMBIE Project (Ice Sheet Mass Balance Intercomparison Project) which uses three decades of satellite data to assess the ice sheets. You can read their most recent report in Earth System Science Data from 2023, which estimates ice losses from these regions since 1992.

Another recent study from December 2024, led by CPOM PhD Researcher, Nitin Ravinder, and published in Geophysical Research Letters, showed that the Greenland ice sheet lost 2347 km3 of ice during the period since 2010 – which has contributed roughly ‘the amount of water stored in Africa’s Lake Victoria’ to the Earth’s oceans. Here’s an animation from Planetary Visions based on this study showing these changes in the Greenland ice sheet.

As sea level rise will affect many millions of people around the world, as well as the numerous at-risk species in coastal habitats, it’s vital that Governments and international bodies are able to plan for this rise. Computer modelling (simulations) is the only way we can accurately predict how the ice sheets might behave in the future.

CPOM provides UK National Capability research in ice sheet modelling, developing the BISICLES model.

BISICLES is a numerical model (simulation) that works with high resolution simulations around the margins of ice sheets (the grounding line), where interactions between the ice sheet and the ocean and atmosphere are the most complex. This is particularly useful when looking at the Greenland ice sheet.

Scientists from CPOM recently worked on combining this system as the ice sheet component within the UKESM (The UK Earth System Model), allowing us to better explore and understand the interactions between the ice sheets and the global ocean and atmospheric circulations (and providing evidence for IPCC reporting).

BISICLES has also been integrated into large international projects such as ISMIP (Ice Sheet Model Intercomparison Project) to help project future changes to global sea levels, something that is particularly difficult to predict beyond the end of the century with one model alone.

The behaviour of the Greenland ice sheet is particularly difficult to predict, as over recent years we have seen points where melting has been more rapid than anticipated, but also points where it has been less than expected. We need to continually hone and improve computer simulations (or models) that can accurately predict how these ice sheets might behave in a rapidly warming planet to account for the complexity of the interactions between the ice sheets and the atmosphere in these regions.

Understanding this part of the world is vital for understanding how we might protect the rest of the Earth in the years to come. By combining expertise in land ice Earth observation with modelling simulations, like BISICLES, CPOM is continuing to increase the accuracy of future projections of sea level rise and weather changes, leading from the melting of the Greenland ice sheet.

Image credit: Professor Andrew Shepherd

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