A recent, rapid heating of the world’s oceans has alarmed scientists concerned that it will add to global warming.
This month, the global sea surface hit a new record high temperature. It has never warmed this much, this quickly.
Scientists don’t fully understand why this has happened.
But they worry that, combined with other weather events, the world’s temperature could reach a concerning new level by the end of next year.
Experts believe that a strong El Niño weather event – a weather system that heats the ocean – will also set in over the next months.
Warmer oceans can kill off marine life, lead to more extreme weather and raise sea levels. They are also less efficient at absorbing planet-warming greenhouse gases.
An important new study, published last week with little fanfare, highlights a worrying development.
Over the past 15 years, the Earth’s accumulated heat has increased by 50%, with most of the extra going into the oceans.
This is having real world consequences – not only did the overall temperature of the oceans hit a new record in April this year, in some regions the difference from the long term was enormous.
In March, sea surface temperatures off the east coast of North America were as much as 13.8C higher than the 1981-2011 average.
“It’s not yet well established, why such a rapid change, and such a huge change is happening,” said Karina Von Schuckmann, the lead author of the new study and an oceanographer at the research group Mercator Ocean International.
“We have doubled the heat in the climate system the last 15 years, I don’t want to say this is climate change, or natural variability or a mixture of both, we don’t know yet. But we do see this change.”
One factor that could be influencing the level of heat going into the oceans is, interestingly, a reduction in pollution from shipping.
In 2020, the International Maritime Organisation put in place a regulation to reduce the sulphur content of fuel burned by ships.
This has had a rapid impact, reducing the amount of aerosol particles released into the atmosphere.
But aerosols that dirty the air also help reflect heat back into space – removing them may have caused more heat to enter the waters.