Glacier melt has raised sea levels by nearly 2cm this century, scientists have revealed.
The world’s glaciers lost 6,542 billion tonnes of ice, contributing 18mm to global sea-level rise between 2000 and 2023 alone.
On average 273 billion tonnes of ice are being lost a year – equivalent to 30 years of water consumption by the entire world’s population.
Scientists also found a stark increase in the amount of ice lost over the past 10 years compared with the start of the century.
Some 36% more ice melted in 2012 to 2023 than in 2000 to 2011, a decades-long study has found.
Professor Martin Siegert, Professor of geosciences and deputy Vice Chancellor at the University of Exeter, said: “2cm might not sound a lot, but this is the contribution from small glaciers – not the whole of the ice on the planet, and not from Greenland and Antarctica.
“Sea level has risen by 20cm since 1850; 50% from the sea being warmer and expanding, 50% (10cm) due to glacier melt.
“However, ice sheets are now losing mass at increasing rates, six times more than 30 years ago, and when they change we stop talking cms and start talking metres.
“This research is concerning to us, because it predicts further glacier loss, which can be considered like a ‘canary in the coal mine’ for ice sheet reaction to global warming and far more sea level this century and beyond.”
In 2002, glaciers – excluding the continental ice sheets of Greenland and Antarctica – spanned 705,221 sq km and held an estimated 121,728 billion tonnes of ice.
An international research team, led by the Universities of Edinburgh and Zurich, found that over the past two decades, glaciers have lost approximately 5% of their total volume.
Professor Andrew Shepherd, head of Department of geography and environmental science at Northumbria University, said: “It confirms that the pace of glacier melting is accelerating over time.
“Glacier melting has two main impacts; it causes sea level rise and it disrupts the water supply in rivers that are fed by meltwater.
“Around two billion people depend on meltwater from glaciers and so their retreat is a big problem for society – it’s not just that we are losing them from our landscape, they are an important part of our daily lives.
“Even small amounts of sea level rise matter because it leads to more frequent coastal flooding. Every centimetre of sea level rise exposes another two million people to annual flooding somewhere on our planet.”
Glaciers are the second-largest contributor to global sea-level rise, following ocean warming.
They are also natural indicators of climate change, and play a vital role in many communities providing vital water resources, especially during dry seasons and sustaining hydropower energy, experts say.
The research, published in the journal Nature, is part of the Glacier Mass Balance Intercomparison Exercise – known as GlaMBIE.
Professor Noel Gourmelen, study co-lead and personal chair of Earth observation of the University of Edinburgh’s School of GeoSciences, said: “This research is the result of sustained efforts by the community and by space agencies over many years, to exploit a variety of satellites that were not initially specifically designed for the task of monitoring glaciers globally. “
