A new study of the melting of vast ice sheets, which once covered Ireland over 20,000 years ago could have implications for understanding how glaciers and ice sheets will respond to climate warming today, according to the British Antarctic Survey (BAS).

The study, published in the journal Quaternary Science Reviews, found that the melting ice thousands of years ago carved deep valleys now buried under the seafloor of the North Sea.

It shows how the ancient ice sheets that covered much of Ireland, Britain and northern Europe, expelled water beneath the surface to stop themselves from collapsing.

Traditionally, the drainage of water from beneath ice sheets is thought to stabilise ice flow, a process that could potentially buffer modern ice sheets from collapse in a warming climate.

"The pace at which these giant channels can form means that they are an important, yet currently ignored, mechanism that may potentially help to stabilise ice sheets in a warming world," explains James Kirkham, lead author of the study who is from the BAS and the University of Cambridge.

"As climate change continues to drive the retreat of the modern-day Greenland and Antarctic ice sheets, at ever increasing rates, our results call for renewed investigation of how tunnel valleys may help to stabilise contemporary ice losses."

He said the study may have implications for sea level rise, if similar vast tunnels "switch on beneath the Earth's ice sheets in the future".

However, the researchers say more study is needed of these enormous tunnel valleys, some of which are up to 500 metres deep and up to 150km long and 6km wide - each several times larger than Loch Ness in Scotland.

An aerial view of meltwater lakes formed at the Russell Glacier front, part of the Greenland ice sheet

Detailed seismic images were used for the study, providing a 3D scan of the Earth's buried layers.

The research suggests that the giant tunnels were formed within hundreds of years, which is relatively quick in terms of geological timescales.

A study published last month on science.org suggested the world is closer than previously thought to crossing several "tipping points" which could make global warming self-perpetuating, leading to the possible collapse of the Greenland ice sheet and rising sea levels.

The BAS study does not make this any less likely, but shows there could be more going on beneath current ice sheets and glaciers than is currently understood.

"We have been observing these huge meltwater channels from areas covered by ice sheets in the past for more than a century, but we did not really understand how they formed," said Dr Kelly Hogan, co-author and a geophysicist at BAS.

"Surface melting is already hugely important for the Greenland ice sheet today, and this process of water transport through the (ice) system will only increase as our climate warms," said Dr Hogan.

"The crucial question now is will this 'extra' meltwater flow in channels cause our ice sheets to flow more quickly, or more slowly, into the sea?"