2023 witnesses highest ocean heat on record: study

Human activities have significantly increased the levels of carbon dioxide (CO2) and other greenhouse gases in the atmosphere. This has led to a rise in trapped longwave radiation within the Earth system, resulting in an Earth Energy Imbalance (EEI). The world's oceans absorb about 90% of the excess heat generated, causing a surge in ocean temperatures and Ocean Heat Content (OHC).

The study draws data from the Institute of Atmospheric Physics (IAP) at the Chinese Academy of Sciences (CAS) and the National Centers for Environmental Information of the National Oceanic and Atmospheric Administration (NOAA), highlighting the critical role the ocean plays in Earth’s climate system.

In 2023, the world’s oceans absorbed a lot of extra heat. This heat was so much that it could have evaporated billions of swimming pools, according to a report released on Thursday.

During El Niño events, heat moves from the deeper parts of the ocean to the top, making the sea surface warmer. This leads to higher average global temperatures. In 2023, the sea surface was hotter than ever before, with the yearly average temperature being 0.23°C higher than in 2022 and 0.54°C higher than the average from 1981 to 2020.

Oceans absorbed more heat in 2023

In 2023, the oceans absorbed about 9 to 15 zettajoules more heat than they did in 2022. This is according to estimates from the US National Oceanic and Atmospheric Administration (NOAA) and the Chinese Institute of Atmospheric Physics (IAP).

One zettajoule of energy is roughly equivalent to ten times the electricity generated worldwide in a year. "Annually the entire globe consumes around half a zettajoule of energy to fuel our economies", according to statement. "Another way to think about this is 15 zettajoules is enough energy to boil away 2.3 billion Olympic-sized swimming pools."

Changes in ocean salinity, reflecting alterations in the atmospheric water cycle and ocean circulation, contribute to ocean freshwater variations. This includes a noticeable pattern termed "fresh gets fresher, salty gets saltier." These changes are quantified by a "salinity-contrast" (SC) index, measuring the salinity difference between higher and lower salinity regions globally.

However, these oceanic changes are not uniform spatially. The non-uniformity has led to increased variance in the three-dimensional upper 2000 m ocean temperature fields. These changes also affect ocean temperature and density structures vertically, influencing the exchanges of energy, water, carbon, and nutrients.

The energy that oceans store is a crucial measure of global warming. This is because it’s less influenced by natural changes in climate compared to the temperature at the ocean’s surface.

Study analyzes ocean data, ensures accuracy

The study utilizes data analyzing various oceanic parameters, including OHC, SST, SC index, stratification, and temperature spatial inhomogeneity indexes, using two different datasets.

Spatial maps highlighted significant ocean warming, with some regions, like the Atlantic, North Pacific, Western Pacific, and southern oceans, heating at a faster rate than the global average. These changes underscore the impact of El Niño on oceanic and atmospheric conditions, emphasizing the broader implications for climate change.

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