Greenland’s glaciers have melted five times faster in the last two decades than ever before, say scientists.
Researchers at the University of Copenhagen and Arizona State University examined satellite images and historical aerial photographs found in a castle outside Copenhagen 15 years ago and initially taken by the military. The joint research team, led by Laura Larocca of Arizona’s School of Ocean Futures, tracked over a thousand so-called “land-terminating” glaciers, or glaciers that terminate inland, often neglected in other studies. The main way that these melt and lose mass is through surface channels and melt ponds (called supraglacial lakes).
Glaciers retreating 25 metres per year
The new study, published in Nature Climate Change journal, found that the glaciers have retreated twice as fast this century than in the previous 100 years, averaging a loss of 25 metres per year for the last 20 years, versus around 6 metres per year in the 20th century.
The reason for the accelerated melt? Human-induced climate change, with the world’s temperature now 1.2°C above pre-industrial levels (1850-1900). As recently reported by Travel Tomorrow, global average temperatures in 2023 were hotter than ever. The Arctic is particularly badly affected by the warming – with its temperature increasing four times faster than elsewhere. It even rained at the summit of Greenland’s ice sheet for the first time since records began in 2021.
The rapid rate of glacier loss is likely to continue if predictions that the effects of the current El Niño conditions will go on and even intensify into 2024 and beyond.
Why does it matter?
Northern Greenland’s gigantic glaciers and ice sheets were once believed to be stable entities and many may remember terms like “permafrost” that date back to the 1940s and give a false sense of security about the behaviours of polar ice mass behaviour.
The rapid melting of glaciers now being witnessed could raise sea levels globally by as much as 6 metres if all their water were to melt into the sea. NASA has also been tracking sea level rise for 30 years and has found that by the early 1990s, it was about 2.5 mm per year, a millimetre more than over the 20th century. Over the past decade, the rate has increased to 3.9 mm per year
The rise of sea level caused by human interference with the climate now dwarfs the natural cycles. And it is happening faster and faster every decade.Josh Willis, an Oceanographer at the Jet Propulsion Laboratory and NASA Project Scientist
While this may seem insignificant, scientists estimate that for every 2.5 centimeters of sea level rise, 2.5 meters of beachfront are lost along the average coast. As sea levels rise, tides and storm surges can become greater, causing coasting flooding, even on sunny days.
Now the latest study shows that 21% of the increase in sea level between 2006 and 2018 is due to the land-terminating glaciers, while the melting ice sheet has contributed 17.3%. This means the rapid loss of the peripheral glaciers (just 4% of the whole) is contributing disproportionately to rising sea levels.
The findings underscore “the urgency for immediate climate action to limit global temperature rise”, the authors said.