deep water

When these deep waters rise again, they deliver this accumulated acidity back to the surface, where the water interacts with atmospheric CO2 and becomes even more acidic.

The researchers describe a process in which phosphorus delivered by upwelling deep water and nitrogen supplied by nitrogen-fixing bacteria together fuel the blooms seen over past decades.

Four heat exchangers are submerged in the 1.7 metre deep water, which is also home to dozens of koi carp and tench – fish that have their own role in the operation.

Commuters have been seen wading through deep water to access the station over the past year, while a charity warns the area could become a "no-go zone" for disabled people.

To determine why warm deep water intensified during that period, the researchers ran climate and ocean circulation models.