Greenland’s vast ice sheet could melt faster than previously thought over the 21st century, according to a new study.

The Greenland ice sheet is the second largest mass of ice on Earth, holding enough water to raise global sea levels by 7.2 metres. Even if warming in the coming decades is kept to low levels, melting from the Greenland ice sheet is expected to reach unprecedented rates in the coming decades, contributing significantly to global sea level rise.

The study, published in Nature Communications, compares estimates of future sea level rise from the Greenland ice sheet in new (CMIP6) models to the previous generation (CMIP5). The study finds that the 21st century sea-level contribution from the Greenland ice sheet is always higher in the CMIP6 models than in the corresponding CMIP5 models running the same emissions scenario. (See Carbon Brief’s detailed CMIP6 explainer.) 

This is mainly because CMIP6 models project a greater temperature increase over the 21st century, the study finds. For example, the researchers find that in a very high emissions scenario, the new models predict a 22-day longer melt season than the old models by the end of the 21st century. 

Overall, the researchers estimate that 21st century sea level rise from Greenland would be 2.6cm higher under a low-emission future scenario in the CMIP6 simulations, 2.8cm higher under a medium-emission scenario and 5cm higher under a high-emission scenario.