Fuelled by climate change, the world’s oceans have broken temperature records every single day over the past year, a BBC analysis finds. Nearly 50 days have smashed existing highs for the time of year by the largest margin in the satellite era. Planet-warming gases are mostly to blame, but the natural weather event El Niño has also helped warm the seas.
The super-heated oceans have hit marine life hard and driven a new wave of coral bleaching.
The analysis is based on data from the EU’s Copernicus Climate Service.
Copernicus also confirmed that last month was the warmest April on record in terms of global air temperatures, extending that sequence of month-specific records to 11 in a row.
For many decades, the world’s oceans have been the Earth’s ‘get-out-of-jail card’ when it comes to climate change.
Not only do they absorb around a quarter of the carbon dioxide that humans produce, they also soak up around 90% of the excess heat.
But over the past year, the oceans have displayed the most concerning evidence yet that they are struggling to cope, with the sea surface particularly feeling the heat.
From March 2023, the average surface temperature of the global oceans started to shoot further and further above the long-term norm, hitting a new record high in August.
Recent months have brought no respite, with the sea surface reaching a new global average daily high of 21.09C in February and March this year, according to Copernicus data.
As the graph below shows, not only has every single day since 4 May 2023 broken the daily record for the time of year, but on some days the margin has been huge.
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