Greenland’s ice shelves have shrunk by more than a THIRD since 1978 – and will cause global sea levels to rise by 6.8 FEET if they collapse entirely, study warns

Greenland’s ice shelves have lost more than a third of their volume since 1978, researchers have warned.

Warmer ocean waters have accelerated the disintegration of vital ice shelves, causing them to melt from below and increasing their risk of collapse.

Of the eight ice shelves that support the vast glaciers of northern Greenland, three have already collapsed completely, while the remaining five have retreated rapidly.

As ocean temperatures continue to rise, scientists say ice shelves will continue to retreat, with dire consequences for global sea levels.

If they disappeared entirely, these ice shelves could release enough water to raise global sea levels by 6.8 feet (2.1 metres), according to experts from the French National Center for Scientific Research (CNRS).

Greenland’s ice shelves were previously thought to be stable, unlike more sensitive areas of the polar ice sheet.

However, scientists have used field observations, aerial photography, satellite data, and regional climate models to show that the ice shelves have undergone accelerating collapse.

Since the 2000s, the floating ice shelves of the Zacharia-Eström, Ostenfeld and Hagen-Bray glaciers have completely collapsed.

In 2003, 80% of the Ostenfeld ice shelf collapsed into the sea, resulting in the loss of 6.5 cubic miles (27 km³) of ice.

Likewise, the Hagen Overland collapsed between 2001 and 2005, leaving behind just over a tenth of its original mass.

Other remaining ice shelves also thinned and shrunk rapidly, with some retreating as much as five miles (8.3 km).

The danger of these collapses is that they will increase The rate at which ice enters the ocean, which can have a huge impact on sea levels.

Ice shelves act like giant frozen dams, preventing glaciers from entering the sea.

Greenland is already responsible for 17.3% of the rise in sea levels between 2006 and 2018.

However, the glaciers in northern Greenland contain enough ice to raise sea levels by 6.6 feet (2.1 metres).

Writing in Nature Communications“Overall, 25% of the ice sheet area is being drained by former or remaining ice shelves, representing a sea level rise equivalent to 2.1 metres,” said researchers led by Roman Milan.

“If northern Greenland’s glaciers lose the support provided by ice shelves, the increase in drainage could rival the largest contributors to Greenland’s ice mass loss.”

Researchers say the driving factor behind the rapid disintegration of the Greenland ice sheet is rising ocean waters Temperatures.

Ocean temperatures in western North Greenland rose modestly between 1965 and 2000, rising from 31.8 degrees.°Fahrenheit (-0.1°C) to 32°F (0.0°C).

However, between 2000 and 2015, ocean temperatures increased faster, rising from 32°F (0.0°C) to 32.45°F (0.3°C).

In the Northeast, temperatures rose faster, rising from 32.7°F (0.4°C) to 34.2°F (1.2°C) between 1990 and 2020.

“The observed increase in melting coincides with a clear rise in potential ocean warming, indicating a strong oceanic control on ice shelf changes,” the authors added.

Recent studies suggest that a worst-case scenario, in which global temperatures continue to rise at the current pace, could result in ocean levels rising an additional 4.6 feet by 2150.

If global emissions were reduced only weakly, temperatures could triple, according to scientists from Busan National University in South Korea and Fabian Schlosser of the University of Hawaii.

Even limiting global warming to no more than 2°C above pre-industrial levels – the main goal of the Paris Agreement – ​​will not be enough to slow the rate of rise in sea levels.

The new study warns that only by limiting global temperature rise to less than 3.2 degrees Fahrenheit (1.8 degrees Celsius) compared to pre-industrial levels by the end of this century can accelerating sea level rise be avoided.

If sea levels continue to rise at current rates, large parts of the UK could be at risk of flooding.