Brussels: Rain fell at the highest point on the Greenland ice sheet last week for the first time on record in another worrying sign of warming for the ice sheet already melting at an increasing rate.
“That’s not a healthy sign for an ice sheet,” said Indrani Das, a glaciologist with Columbia University’s Lamont-Doherty Earth Observatory said on Saturday (AEST). “Water on ice is bad. It makes the ice sheet more prone to surface melt.”
The rain fell for several hours at the ice sheet’s 3216-metre summit on August 14, where temperatures remained above freezing for about nine hours, scientists at the US National Snow and Ice Data Centre said.
Temperatures at the ice cap rarely lift above freezing, but have now done so three times since 2012.
Not only is melting water warmer than the usual snow, it’s also darker – so it absorbs more sunlight rather than reflecting it away.
That meltwater is streaming into the ocean, causing sea levels to rise. Already, melting from Greenland’s ice sheet – the world’s second-largest after Antarctica’s – has caused about 25 per cent of global sea level rise seen over the last few decades, scientists estimate. That share is expected to grow, as global temperatures increase.
In total, 7 billion tonnes of rain fell across Greenland over three days, from August 14 through August 16 – the largest amount since records began in 1950.
The rain and high temperatures triggered extensive melting across the island, which suffered a surface ice mass loss on August 15 that was seven times above the average for mid-August.