World's glaciers melting at an accelerated pace, finds new study

Glaciers are melting at an accelerating rate around the world, according to a comprehensive new study.

After assessing the behaviour of almost all documented ice streams on Earth French researchers found that almost 270 billion tonnes of ice have been lost per year since the start of the 21st century.

The water produced as a result now accounts for around a fifth of global sea-level rise, say scientists.

Speaking to BBC World Service, team member Robert McNabb ,from the universities of Ulster and Oslo, said:

"Over the last 20 years, we've seen that glaciers have lost about 267 gigatonnes (Gt) per year. So, if we take that amount of water and we divide it up across the island of Ireland, that's enough to cover all of Ireland in 3m of water each year”.

"And the total loss is accelerating. It's growing by about 48Gt/yr, per decade."

The team, led by Romain Hugonnet from the University of Toulouse, France, used imagery acquired by Nasa's Terra satellite to assess the level of ice loss.

Using immense computing power to interpret the images, the researchers were able to ascertain changes on the volume, mass and elevation of glaciers up to the year 2019.

They believe they’ve managed to hammer down uncertainties in results to less than 5 per cent overall.

"This new study is a major advance as we get a high spatial resolution and, at the same time, it also provides the temporal change over the two decades directly based on satellite data, which is novel," explained co-author Matthias Huss from the Swiss Federal Institute of Technology, speaking to the BBC.

"This data-set has been validated with an immense amount of additional, independent measurements and is highly accurate so that the uncertainties of previous studies are strongly reduced."

Similar results emerged from an assessment of glacier ice loss led by Leeds University and published in January.

Leeds professor Andy Shepherd told BBC News: "Glacier melting accounts for a quarter of Earth's ice loss over the satellite era, and the changes taking place are disrupting water supplies for billions of people downstream - especially in years of drought when meltwater becomes a critical source.

"Although the rate of glacier melting has increased steadily, the pace has been dwarfed by the accelerating ice losses from Antarctica and Greenland, and they remain our primary concern for future sea-level rise."