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SOURCE: The Guardian
DATE: January 13, 2021
SNIP: The world’s oceans reached their hottest level in recorded history in 2020, supercharging the extreme weather impacts of the climate emergency, scientists have reported.

More than 90% of the heat trapped by carbon emissions is absorbed by the oceans, making their warmth an undeniable signal of the accelerating crisis. The researchers found the five hottest years in the oceans had occurred since 2015, and that the rate of heating since 1986 was eight times higher than that from 1960-85.

Reliable instrumental measurements stretch back to 1940 but it is likely the oceans are now at their hottest for 1,000 years and heating faster than any time in the last 2,000 years. Warmer seas provide more energy to storms, making them more severe, and there were a record 29 tropical storms in the Atlantic in 2020.

Hotter oceans also disrupt rainfall patterns, which lead to floods, droughts and wildfires. Heat also causes seawater to expand and drive up sea levels. Scientists expect about 1 metre of sea level rise by the end of the century, endangering 150 million people worldwide.

Furthermore, warmer water is less able to dissolve carbon dioxide. Currently, 30% of carbon emissions are absorbed by the oceans, limiting the heating effect of humanity’s burning of fossil fuels.

“Ocean warming is the key metric and 2020 continued a long series of record-breaking years, showing the unabated continuation of global warming,” said Prof John Abraham, at the University of St Thomas in Minnesota, US, and one of the team behind the new analysis.

“Warmer oceans supercharge the weather, impacting the biological systems of the planet as well as human society. Climate change is literally killing people and we are not doing enough to stop it.”

Recent research has shown higher temperatures in the seas are also harming marine life, with the number of ocean heatwaves increasing sharply.

The oceans cover 71% of the planet and water can absorb thousands of times more heat than air, which is why 93% of global heating is taken up by the seas. But surface air temperatures, which affect people most directly, also rose in 2020 to the joint highest on record.

The average global air temperature in 2020 was 1.25C higher than the pre-industrial period, dangerously close to the 1.5C target set by the world’s nations to avoid the worst impacts.

The latest research, published in the journal Advances in Atmospheric Sciences, showed the oceans absorbed 20 zettajoules more heat than in 2019. This is equivalent to every person on Earth running 80 hairdryers all day, every day, or the detonation of about four atomic bombs a second.