Scientists from the University of East Anglia have helped discover an active volcanic heat source beneath Antarctica's fastest melting glacier.

They are part of an international team to find that a volcanic heat source under the Pine Island Glacier plays an important role in its movement and melting.

But the research team say climate change is still causing the bulk of glacial melt.

Prof Karen Heywood, the expedition's chief scientist, from UEA's School of Environmental Sciences, said: 'We measured a gas called helium in the water coming out of the cavity beneath a floating ice shelf. This gas comes from the earth's mantle, where there are active volcanoes under the Antarctic ice sheet.

The discovery of volcanoes beneath the Antarctic ice sheet means there is an additional source of heat to melt the ice, lubricate its passage towards the sea, and adding to the melting from warm ocean waters.

'It will be important to include this in our efforts to estimate whether Antarctic ice sheet might become unstable and further increase sea level rise.'

The team conducted a major expedition to Antarctica in 2014 and worked aboard an icebreaker, the RRS James Clark Ross, from January to March - Antarctica's summer.

The West Antarctic Ice Sheet lies atop a major volcanic rift system, but there had been no evidence of current magmatic activity. The last such activity was 2,200 years ago.

And while volcanic heat can be traced to dormant volcanoes, what the scientists found at Pine Island was new.

Lead researcher Prof Brice Loose, from the University of Rhode Island (US) said: 'We weren't looking for volcanism. When we first started seeing high concentrations of helium-3, we thought we had a cluster of bad or suspicious data.

'When you find helium-3, it's like a fingerprint for volcanism. We found that it is relatively abundant in the seawater at the Pine Island shelf.'

However, the team have cautioned that the findings do not imply that volcanism is the major source of mass loss from Pine Island.

Prof Loose said: 'There are several decades of research documenting the heat from ocean currents is destabilizing Pine Island Glacier, which in turn appears to be related to a change in the climatological winds around Antarctica.'