Global sea levels crept a little bit higher a little bit faster last year, driven both by melting ice on land and expansion of seawater due to higher temperatures.
Sea levels have been rising for years due to global warming, but they rose 5.9mm in 2024 when they were expected to only increase 4.3mm, according to Nasa.
“Every year is a little bit different, but what’s clear is that the ocean continues to rise, and the rate of rise is getting faster and faster,” says Nasa’s Josh Willis.
There are similarly worrying messages in the latest State of the Global Climate report. Released this month by the World Meteorological Organization, it notes that the annual rate of sea level rise has more than doubled since satellite measurements began. Between 1993 and 2002 it was 2.1mm. By 2015-2024 it had reached 4.7mm.
These are small numbers but the phenomenon they show will make some low-lying islands and coastal regions uninhabitable in the years ahead. The BBC recently reported from Gardi Sugdub in Panama, where people are being relocated as the government fears the island will be uninhabitable by 2050. CNN, meanwhile, has been reporting from Egypt, where the city of Alexandria is seeing a rash of building collapses due to rising seas.
So just how much worse might things get? In a paper published at the end of last year, a team of researchers tried to reconcile various future projections. Fusing models and expert opinions they produced a “very likely” range for various future levels of greenhouse gas emissions. In a low-emissions future, this suggested global mean sea-level would rise between 0.3 and 1.0m by 2100. If emissions are high, this goes up to between 0.5 and 1.9m.
In a recent article in The Conversation, two of the authors suggest that, “Given that we will likely exceed 2C warming, preparing for more than a metre of sea-level rise by 2100 is, therefore, necessary.”