Glaciers are melting – sea levels have risen by three centimetres

Greenland and Antarctica have lost 11.3 trillion tonnes of ice since the 1970s. This has raised global sea levels by more than three centimetres, according to a new study.

Professor Andrew Shepherd, founder of The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE), which carried out the study, comments that a rise of three centimetres may sound small.

´But it means that a further six to nine million people are at risk of flooding and erosion along the coasts. As the ice sheets are expected to lose significantly more ice in the coming decades, global assessments are crucial to protecting the communities affected by climate change.´

Flowing faster

The majority of the loss is not due to surface melting, but to glaciers flowing faster into the sea, according to the study in which polar researchers have compiled satellite data from the 1970s onwards.

‘This shows that the long-term trend is driven by the ice sheets’ dynamic response to a warming ocean,’ says Inès Otosaka, who led the study, in a comment.

The polar ice sheets currently account for around a quarter of global sea-level rise.

Sharply reduced

The ice sheets have shrunk sharply from the 1990s onwards. Greenland has seen the amount of ice lost increase from around 60 billion tonnes per year in the 1980s to 264 billion in the 2010s.

Antarctica’s losses rose from around 48 billion tonnes per year in the 1980s to 202 billion tonnes in the 2010s.

In the most recently studied years, 2020–2023, ice loss has temporarily slowed. Record snowfall over East Antarctica has offset glacier losses elsewhere, whilst a series of milder summers in Greenland has reduced surface melting by about half. However, the researchers emphasise that these are temporary fluctuations.

The study has been published in the journal Scientific Data.