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Oceanic acidity at highest level for at least 26,000 years, WMO report finds

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The world’s oceans are at their most acidic level for at least 26,000 years, according to a report from the World Meteorological Organisation (WMO) which made some striking warnings about climate change.

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 also said that extreme weather events have led to hundreds of billions of dollars in economic losses and triggered shocks for food and water security and displacement that have accentuated in 2022.

The past seven years have been the warmest on record, although 2021 was only one of the seven warmest because of a La Niña event at the start and end of the year. While this had a temporary cooling effect, it did not reverse the overall trend of rising temperatures, the report said. The average global temperature in 2021 was about 1.11°C above the pre-industrial level.

Last year, climate experts said there is a 40 per cent chance that global temperatures could temporarily exceed 1.5°C above pre-industrial levels in the next five years.

United Nations secretary-general António Guterres used the publication of the WMO report to call for urgent action to grab the “low-hanging fruit” of transforming energy systems away from the “dead end” of fossil fuels to renewable energy.

“Renewables are the only path to real energy security, stable power prices and sustainable employment opportunities. If we act together, the renewable energy transformation can be the peace project of the 21st century,” he said in a video message.

He proposed five critical actions to jump-start the renewable energy transition including greater access to renewable energy technology and supplies, a tripling of private and public investments in renewables and an end to subsidies on fossil fuels which amount to roughly $11m per minute according to current estimates.

E&T looked at the problems of how scientists are tackling the world's dead oceans in our recent issue.

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