Extreme glacier melt and record ocean heat levels – which cause water to expand – contributed to an average rise in sea levels of 4.62mm a year between 2013-2022, the U.N. agency said in a major report detailing the havoc of climate change. That is about double the pace of the first decade on record, 1993-2002, leading to a total increase of over 10 cm since the early 1990s.

Rising sea levels threaten some coastal cities and the very existence of low-lying states such as the island of Tuvalu – which plans to build a digital version of itself in case it is submerged.

“This report shows that, once again, greenhouse gas concentrations in the atmosphere continue to reach record levels – contributing to warming of the land and ocean, melting of ice sheets and glaciers, rising sea levels, and warming and acidifying of oceans,” WMO Secretary-General Petteri Taalas said in a foreword.

The annual report, released a day ahead of Earth Day, also showed that sea ice in Antarctica receded to record lows last June and July. Oceans were the warmest on record, with around 58% of their surfaces experiencing a marine heatwave, it said.

Overall, the WMO said 2022 ranked as the fifth or sixth warmest year on record with the mean global temperature 1.15 degrees Celsius above the pre-industrial average, despite the cooling impact of a three-year La Niña climatic event.

Climate scientists have warned that the world could breach a new average temperature record in 2023 or 2024, fuelled by climate change and the anticipated return of warming El Nine conditions.

By Emma Farge

(Reporting by Emma FargeEditing by Mark Heinrich)