A groundbreaking study conducted by an international team of researchers, including scientists from the Institute of Atmospheric Physics at the Chinese Academy of Sciences, has revealed alarming findings about the state of our oceans. The research, published in the prestigious journal Advances in Atmospheric Sciences, presents a detailed analysis of global ocean temperatures.
According to the study, conducted by a team of 54 scientists from seven countries, the ocean heat content (OHC) reached a record high in 2024, increasing by an unprecedented 16 ± 8 ZJ (zettajoules, where 1 ZJ equals joules, with a 95% confidence interval). This staggering increase is roughly 140 times the global electricity production in 2023.
For context, ocean heat content (OHC) refers to the amount of heat stored in the ocean from the surface to a depth of 2000 meters.
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| Global upper 2000 m OHC changes from 1955 through 2024 (units: ZJ) |
The Hottest Years for the Oceans: 2020–2024
Since 1955, the five hottest years for global ocean temperatures have been from 2020 to 2024, with new records set each year. The ocean heat content (OHC) values, measured in zettajoules (ZJ), are based on the average for 1981–2010 and account for the upper 2000 meters of ocean depth. The continuous rise in OHC values is a concerning trend, as it could contribute to increased uncertainty about the future and further alter the Earth's energy imbalance (EEI).
The year 2024 was marked by record-breaking changes in the Earth's climate system and widespread anomalous weather patterns, underscoring the growing uncertainty surrounding the planet's climate trajectory. Numerous regions around the globe experienced unprecedented highs in daily, monthly, and yearly temperatures. These extreme conditions led to a surge in droughts, floods, crop failures, heatwaves, and wildfires, amplifying the consequences of an increasingly warming planet.
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| Regional observed upper 2000 m OHC change from 1958 through 2024 relative to a 1981–2010 baseline using IAP/CAS data |
Warming Oceans in 2024: Record Highs in Surface and Subsurface Temperatures
In 2024, global analyses revealed a continued warming trend, not only in sea surface temperatures (SST) but also in the upper 2000 meters of the ocean (OHC). The pace of ocean warming has accelerated in recent decades, with a significant increase observed since the 1990s.
Of the eight major ocean regions analyzed, six reached record-high upper OHC levels within the 2000-meter depth range in 2024. This trend underscores the intensifying impact of global warming on the Earth's oceans, with far-reaching implications for marine ecosystems and climate systems alike.
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| 2024 OHC (0-2000 m) anomaly relative to 2023 (IAP/CAS) |
Ocean Heat Trends: 1958–2024
A vertical cross-section of average ocean temperature trends between the surface and 2000 meters from 1958 to 2024 reveals that sea temperatures have risen across most surface areas. Among the ocean basins, the Atlantic displays stronger and deeper changes in average ocean heat content (OHC) compared to the Indian and Pacific basins.
This pronounced increase in heat absorption in the Atlantic is attributed to the transfer of heat from the Indo-Pacific to the Atlantic basin, along with changes in aerosols, which have further amplified the Atlantic's capacity to absorb heat.
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| Vertical section of the zonal mean ocean temperature trends within 1958 to 2024 from the sea surface to 2000 m |
The Impact of Ocean Warming: Intensifying Extreme Weather and Oceanic Phenomena
Ocean warming exacerbates extreme weather and oceanic events, leading to stronger typhoons, hurricanes, and increasingly frequent and intense marine heatwaves. The excess heat and moisture entering the atmosphere amplify these natural disasters, resulting in heavier rainfall, stronger winds, and more severe flooding, making storms more destructive and intense.
Additionally, ocean warming is a major driver of deoxygenation, which poses a significant threat not only to marine life and ecosystems but also to humans and terrestrial ecosystems. Unless carbon emissions from human activities are significantly reduced and global warming is mitigated, the accelerating trend of ocean warming is expected to persist. Consequently, ocean heat content (OHC) is likely to continue breaking records in the years to come.
Photo and content sources: link.springer.com/article - Record High Temperatures in the Ocean in 2024
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