The analysis showed that the oceans were the hottest on record in 2022 | Climate crisis

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The world’s oceans were the hottest on record in 2022, demonstrating the profound and sweeping changes that human emissions have made to the planet’s climate.

More than 90% of the excess heat trapped by greenhouse gas emissions is absorbed into the oceans. Records, which began in 1958, show a relentless rise in ocean temperature, with warming accelerating after 1990.

Sea surface temperatures have a significant impact on the weather in the world. Hotter oceans make extreme weather more intense, causing more intense hurricanes and hurricanes and more moisture in the air, which leads to more heavy rains and flooding. Warmer waters are also expanding, causing sea levels to rise and endangering coastal cities.

Ocean temperature is less affected by natural climate variability than atmospheric temperature, making the oceans an undeniable indicator of global warming.

This past year is expected to be the fourth or fifth highest on record for surface air temperatures when final data is compiled. During 2022, we experienced our third consecutive La Niña event, the coldest phase of an irregular climate cycle centered around the Pacific Ocean that affects global weather patterns. When El Niño returns, global air temperatures will rise even further.

The international team of scientists that produced the new analysis of ocean heat concluded: “The Earth’s energy and water cycle has been dramatically altered by the emission of greenhouse gases from human activities, leading to large-scale changes in the Earth’s climate system.”

Professor John Abraham, from the University of St Thomas in Minnesota and part of the study team, said: “If you want to measure global warming, you want to measure which direction the warming is going, and more than 90% is going into the oceans.

“Measuring the oceans is the most accurate way to determine how unbalanced our planet is.

“The weather is becoming more extreme due to the warming of the oceans and this has serious consequences around the world.”

Professor Michael Mann, from the University of Pennsylvania, who is also part of the team, said: “Warmer oceans mean there is a greater potential for larger precipitation events, as we saw last year in Europe, Australia, and currently on the west coast of the US.”

He said the analysis showed a deeper layer of warm water at the ocean’s surface: “This leads to greater and faster hurricane intensification – something we also saw last year – because the winds are no longer causing the submarine to cool surface waters which would have discouraged intensification.”

Ocean temperature chart

Research released on Monday by the US National Oceanic and Atmospheric Administration shows that many extreme weather events in 2022 have become more likely and more severe due to the climate crisis, such as heavy rains that caused devastating floods in Chad, Niger and Nigeria.

Reliable ocean temperature measurements date back to 1940, but it is likely that the oceans are now at their hottest state in 1,000 years and are warming faster than at any time in the past 2,000 years.

The analysis, published in the journal Advances in Atmospheric Sciences, used temperature data collected by a suite of instruments across the oceans and combined separate analyzes by Chinese and US teams to calculate the enthalpy of the top 2,000 meters, where most of the heating occurs. .

The oceans absorbed about 10 zta more heat in 2022 than they did in 2021, the equivalent of everyone on Earth running 40 hair dryers all day, every day.

The researchers also analyzed salinity, which along with temperature determines water density and is a vital driver of the ocean cycle. The salinity asymmetry index across the oceans reached a record high in 2022, demonstrating the continued amplification of the global hydrological cycle.

Another important feature of the oceans is stratification, where layers of water by density become stronger. This restricts the mixing of deeper, cooler, nutrient-rich waters with surface waters.

The scientists found that the long-standing trend of increased stratification continued in 2022, with “significant scientific, societal and environmental findings”.

One consequence, Abraham said, is that less mixing in the ocean means that the surface layer absorbs less carbon dioxide from the atmosphere, leading to more global warming.

The researchers also said: “There are increasing incidences of record-breaking heat waves and droughts in the Northern Hemisphere, consistent with ocean warming in the mid-latitude Pacific and Atlantic.”

Ocean warming, and the effects of extreme weather, will increase until humanity reaches net zero emissions.

In October, the World Meteorological Organization reported that the concentration of all major greenhouse gases in the atmosphere – carbon dioxide, methane and nitrous oxide – had reached record levels. “We are going in the wrong direction,” said WMO Chair Professor Petteri Taalas.

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