New study reveals that the Greenland Ice Sheet is already committed to at least 27 cm of global sea level rise

A new study published in Nature Climate Change - demonstrates – for the first time – that Greenland’s ice sheet is so out of balance with prevailing Arctic climate that it is irreversibly committed to retreat by at least 59,000 square kilometres, an area much larger than Denmark, Greenland’s protectorate state.
Image Alun Hubbard

Even if all the greenhouse gas emissions driving global warming ceased today, the new study finds that Greenland’s ice loss under current temperatures commits 27 cm to global sea level rise. 

The study was published in Nature Climate Change – by Alun Hubbard,  from the Physical Geography research unit at the University of Oulu and colleagues from Denmark and USA. The research introduces a new method to determine Greenland’s ice disequilibrium with its past climate, which does not rely on complex numerical simulations.   Instead, by taking detailed measurements of Arctic climate from 2000 to 2019 combined with satellite and ice-geophysics data, the team were able to precisely calculate the resulting imbalance in the Greenland Ice Sheet.

Hubbard says “This study is something completely new.  It is based entirely on actual measurements from Greenland over the last two decades combined with well-established analytical theory.   For the first time – we can  determine Greenland’s committed contribution to global sea-level rise with absolute confidence, without the uncertainties and limitations of computer models – which just aren’t yet up to the job.”

The calculated sea level rise is a lot more than current models forecast.  The study indicates that if every year were like the warmer years of 2012, 2016 or 2019, when Greenland experienced heat waves, its irreversible commitment to sea level rise would be much closer to a metre.  This an ominous portent given that these are climate conditions we have already seen, not hypothetical future scenarios.

Hubbard says “Sadly, our results are incredibly sobering.  We find that even at best, the world is committed to 27 cm of sea level rise, but should future climate conditions in Greenland approach those warm years that prevailed in the last two decades – then it’s more like a metre or so of rising seas.”

“That’s a complete catastrophe for low-lying coastal regions of the planet – many of which are already experiencing frequent flooding from hurricanes and storm surges. Our study is an ominous indicator that things are going to get a lot worse, before they improve – and that’s on the assumption that we attain “net zero” carbon emissions in the next decade or so.”

The research article was published in the esteemed Nature Climate Change in August 2022. 

Research article: Box, J.E., Hubbard, A., Bahr, D.B. et al. Greenland ice sheet climate disequilibrium and committed sea-level rise. Nat. Clim. Chang. (2022).

Last updated: 15.9.2022