The 'State of the Global Climate' report found that four key climate change indicators – greenhouse gas concentrations, sea level rise, ocean heat, and ocean acidification – all set new records in 2021. It said the worrying results pointed towards “harmful and long-lasting ramifications” for sustainable development and ecosystems.

The ocean absorbs around 23 per cent of the annual emissions of anthropogenic CO2 to the atmosphere. This reacts with seawater and leads to ocean acidification, which threatens organisms and ecosystem services, as well as food security, tourism and coastal protection.

As the pH of the ocean decreases, its capacity to absorb CO2 from the atmosphere also declines.

The Intergovernmental Panel on Climate Change concluded that “there is very high confidence that open ocean surface pH is now the lowest it has been for at least 26,000 years and current rates of pH change are unprecedented since at least that time.”

The WMO...