Greenland’s ice sheet is beyond point of no return: study
Greenland’s ice sheet is likely to disappear regardless of how quickly greenhouse gas emissions are reduced, with annual snowfall insufficient to replenish the snow and ice lost during summer melting, according to a study from Ohio State University. The research was based on 234 Arctic glaciers during the 34 years to 2018. The loss of all of Greenland’s ice would raise sea levels by six metres, causing many coastal cities to flood. The Arctic has been warming at twice the rate of the rest of the world for the last 30 years.
The Ohio study investigates the Greenland ice sheet's mass balance – the net of mass gained by snow accumulation in its interior and lost from ice melting at its edges – which was stable in the 1990s but has been falling since, and at an increasing pace.
It finds Greenland's outlet glaciers are speeding up due to increased “calving” – where ice breaks off glacier termini. The authors state that glacier retreat in the early 2000s switched the ice sheet to operate in a new dynamic, where its shrinkage will be sustained even if temperatures stabilise. This could result in a sea level rise of over six metres by the year 3000.
A separate study published this month uses satellite measurements to estimate the ice sheet lost one million mt of ice per minute across 2019, totalling 532 billion mt, which is double the average rate post-2003. The authors suspect 2019’s loss – the largest in centuries, and potentially millennia – is due to changing atmospheric dynamics that hold warmer air over the ice sheet. These are themselves the result of climate change.
Looking more broadly, a further academic review of all land-based ice has found the Earth’s surface has lost 28 trillion mt of ice since 1994. This rate, which will result in a metre of sea level rise by 2100, is tracking the Intergovernmental Panel on Climate Change’s worst-case scenario for ice loss.
Nature Communications Earth and Environment