Cracks in Greenland ice sheet ‘accelerating’ under climate change

Cracks in the Greenland ice sheet are accelerating, growing in size and depth as a result of climate change, a study has found.

Greenland, home to the world’s second-largest body of ice, contains enough water to add seven metres to the sea levels if the entire sheet were to melt, with research suggesting ocean levels could be 30 centimetres higher as a result by 2100.

Using more than 8,000 3D satellite surface maps, British researchers found that crevasses in the ice sheet had widened significantly at the fast-flowing edges of the ice sheet between 2016 and 2021, suggesting fissures were forming faster than previously thought.

That has the potential to speed up the loss of ice from Greenland, the researchers said.

“As crevasses grow, they feed the mechanisms that make the ice sheet’s glaciers move faster, driving water and heat to the interior of the ice sheet and accelerating the calving of icebergs into the ocean,” said study co-author Prof Ian Howat, director of the Byrd Polar and Climate Research Centre at Ohio State University in the US.

“These processes can in turn speed up ice flow and lead to the formation of more and deeper crevasses – a domino effect that could drive the loss of ice from Greenland at a faster pace.”

The researchers, led by Durham University in northern England, say they hope their findings will allow scientists to better predict future behaviour of the ice sheet.

The mineral-rich autonomous territory of 55,000 people belongs to Nato member Denmark but hosts a US airbase. President Donald Trump last month said he would not rule out the use of military force to seize control of Greenland.

Greenland has contributed to about 14mm of rising sea levels since 1992 because of increased melting from the ice surface as a result of warmer air temperature and more ice flow into the water in response to warmer ocean temperatures, which are being driven by climate change.

The research discovered accelerations in glacier flow speed associated with significant rises in the size of the cracks at the edges of the ice sheet where large glaciers meet the sea. In some parts, fissures spread by 25 per cent.

That was offset by a reduction in crevasses at Sermeq Kujalleq, the fastest-flowing glacier in Greenland, which underwent a temporary slowdown in movement during the study period.

This balanced the total increase in the size of crevasses across the entire ice sheet during the study period to 4.3 per cent, with an error margin of plus/minus 5.9 per cent. But Sermeq Kujalleq’s flow speed has since started to increase again – suggesting the period of balance between crevasse growth and closure on the ice sheet is now over.

“In a warming world, we would expect to see more crevasses forming,” said the study's lead author Dr Tom Chudley, of the geography department at Durham University. “This is because glaciers are accelerating in response to warmer ocean temperatures and because meltwater filling crevasses can force fractures deeper into the ice. However, until now we haven’t had the data to show where and how fast this is happening across the entirety of the Greenland ice sheet."

But for the first time, significant increases in the size and depth of crevasses at fast-flowing glaciers at the edges of the ice sheet were spotted on timescales of five years and less, he said.

“With this data set we can see that it’s not just that crevasse fields are extending into the ice sheet, as previously observed – instead, change is dominated by existing crevasse fields getting larger and deeper,” he added.

The project which provided the imagery used by researchers will continue to produce high-resolution models until at least 2032, Prof Howat said. “This will allow us to monitor glaciers in Greenland and across the wider Arctic as they continue to respond to climate change in regions experiencing faster rates of warming than anywhere else on Earth,” he added.