(Press-News.org) A new international analysis published in Advances in Atmospheric Sciences on 9 January finds that the Earth’s ocean stored more heat in 2025 than in any year since modern measurements began. The 2025 heat increase was 23 Zetta Joules (23,000,000,000,000,000,000,000 Joules of energy), which is equivalent to ~37 years of global primary energy consumption at the 2023 level (~620 Exa Joules per year). The finding is the result of a major international collaboration, involving more than 50 scientists from 31 research institutions worldwide.
Why are the oceans so important?
The ocean absorbs more than 90% of the excess heat trapped by greenhouse gases, making it the main heat reservoir of the climate system. Because ocean heat content (OHC) reflects the accumulation of heat stored in the ocean, it provides one of the best indicators of long-term climate change.
Study Results
The assessment combines data from major international data centers and independent research groups, including three observational products (Institute of Atmospheric Physics at the Chinese Academy of Sciences; Copernicus Marine; and NOAA/NCEI) and an ocean reanalysis (CIGAR-RT) from three continents: Asia, Europe, and America. These groups confirm that the 2025 OHC reached the highest level on record, confirming continued ocean heat gain.
The ocean warming is not uniform; some areas are warming faster than others. In 2025, about 16% of the global ocean area reached a record-high OHC, and about 33% ranked among the top three warmest values in their historical records. The warmest areas included the tropical and South Atlantic and North Pacific Oceans, and the Southern Ocean.
The overall re cord is characterized by stronger ocean warming trends since the 1990s than before. The increase in upper 2000m OHC is fairly steady in recent decades, though a small increase in rate can be detected. Ocean heat content reached a record high in 2025 as it has in each of the past nine years.
Ocean surface temperatures
Global annual mean sea-surface temperature (SST) in 2025 was the third warmest year in the instrumental record and remained about 0.5 °C (approximately 1°F) above the 1981–2010 average baseline. SST in 2025 is slightly lower than in 2023 and 2024, mainly due to the transition from El Niño to La Niña in the tropical Pacific. Sea surface temperatures are particularly important because they affect weather patterns worldwide. Warmer surface temperatures favor increased evaporation and heavier rains, thus causing more extreme tropical cyclones and weather events. These played a major role in widespread flooding and disruption throughout much of Southeast Asia, drought in the Middle East, and flooding in Mexico and the Pacific Northwest, in 2025.
Why does this matter?
Rising ocean heat drives global sea-level rise via thermal expansion, strengthens and prolongs heatwaves, and intensifies extreme weather by increasing heat and moisture in the atmosphere. As long as the Earth’s heat continues to increase, ocean heat content will continue to rise and records will continue to fall.
The final results will be included in a special collection on Ocean Heat Content Changes organized by the journal Advances in Atmospheric Sciences. Notably, the cartoon characters of the sad shrimp and crab on the cover were suggested by the study's corresponding author, Lijing Cheng from the Institute of Atmospheric Physics at the Chinese Academy of Sciences.
"The idea comes from the 'shrimp soldiers and crab generals' guarding the underwater palace in Journey to the West," said Cheng. "We reimagined them not as mighty guardians, but as vulnerable creatures whose armor—their shells and scales—is under attack by ocean warming, acidification and other ocean environmental changes."
The collection will include various aspects of OHC changes and in-depth analyses of the mechanisms—for instance, regional OHC changes in the seas around China, the South Pacific, and the Indian Ocean. As leading climate scientist Kevin Trenberth wrote in the preface of the special issue, it is structured as an ongoing collection, reflecting the evolving nature of climate science.
While the science continues to evolve, one conclusion remains clear: The biggest climate uncertainty is what humans decide to do. Together, we can reduce emissions, better prepare for upcoming changes, and help safeguard a future climate where humans can thrive.
END
Ocean temperatures reached another record high in 2025
2026-01-09
ELSE PRESS RELEASES FROM THIS DATE:
Dynamically reconfigurable topological routing in nonlinear photonic systems
2026-01-09
Topological photonics has emerged as a powerful paradigm for achieving robust light transport that is immune to imperfections, disorder, and structural defects. By harnessing principles from condensed matter physics, topological photonic systems support edge modes that guide light along boundaries without backscattering — a feature that has significant implications for resilient optical communication and information processing. However, most demonstrations of topological photonics have been confined to linear and static settings, where the transport pathways are fixed once the device is fabricated. This rigidity presents a major limitation for practical ...
Crystallographic engineering enables fast low‑temperature ion transport of TiNb2O7 for cold‑region lithium‑ion batteries
2026-01-09
As fast-charging lithium-ion batteries race toward sub-zero markets, the anode bottleneck—graphite plating risk and Li4Ti5O12 capacity ceiling—intensifies. Now, researchers from Harbin Institute of Technology, led by Prof. Yan Zhang and Prof. Shuaifeng Lou, unveil an Sb/Nb co-doped TiNb2O7 (TNO) anode that unlocks 140 mAh g-1 at 20 C and 500 stable cycles at −30 °C. Published in Nano-Micro Letters, the work delivers a practical pouch cell delivering 1.14 Ah at 17 C with 93.8 % retention ...
Ultrafast sulfur redox dynamics enabled by a PPy@N‑TiO2 Z‑scheme heterojunction photoelectrode for photo‑assisted lithium–sulfur batteries
2026-01-09
While lithium–sulfur batteries (LSBs) promise 2600 Wh kg⁻¹, the sluggish liquid-solid conversion of polysulfides keeps practical capacities far below theory. Now, researchers at Northwestern Polytechnical University, led by Prof. Yibo He, report a free-standing PPy@N-TiO2/Carbon-Cloth photocathode that harvests sunlight to co-drive sulfur redox, delivering 1 653 mAh g-1 (98.7 % of theory) and 333 mAh g-1 after 5 h of pure photo-charging. Published in Nano-Micro Letters, the work realizes dual-mode energy harvesting in a single cell.
Why Photo-Assisted Strategy Matters
Polysulfide ...
Optimized biochar use could cut China’s cropland nitrous oxide emissions by up to half
2026-01-09
Agricultural soils are one of the world’s largest sources of nitrous oxide, a greenhouse gas nearly 300 times more powerful than carbon dioxide over a century. New research suggests that a common agricultural byproduct may offer a powerful and practical solution. A study published in Biochar shows that straw-derived biochar, when applied using region-specific strategies, could reduce nitrous oxide emissions from China’s croplands by as much as 50 percent.
Nitrous oxide is primarily released from soils treated with nitrogen fertilizers. While biochar, a carbon-rich material produced by heating crop residues under low oxygen conditions, has long been ...
Neural progesterone receptors link ovulation and sexual receptivity in medaka
2026-01-09
A research team led by Hiroshima University and Tokyo University of Agriculture and Technology have proposed a neuroendocrine mechanism in bony fish that signals ovulation from the ovaries to the brain, using the medaka fish as a model; the first step to elucidate the neural circuits for facilitation of sexual receptivity in female teleosts.
Bony fish (teleosts) are one of the most diverse groups of vertebrates, inhabiting a wide variety of aquatic environments. Females of many species are sexually receptive only when eggs have developed in the ovaries and are ready for spawning. In other words, sexual ...
A new Japanese study investigates how tariff policies influence long-run economic growth
2026-01-09
Rising trade frictions over the past decade have sparked urgent questions about their long-term impact on global economies. The U.S. now applies tariffs of 66.4% on Chinese exports, which is higher compared to the average rate of 19.3%, while China retaliates with a 58.3% import tariff on U.S. exports, higher than the average rate of 21.1%. These frictions not only disrupt regular trade flow, but also have long-term economic impacts. The geographical location of the market involved also plays an important role and is often influenced ...
Mental trauma succeeds 1 in 7 dog related injuries, claims data suggest
2026-01-09
Mental trauma, including specific phobias and post traumatic stress disorder (PTSD), succeeds 1 in 7 dog related injuries, while over half of cases result in the need for time off work and/or loss of earnings, suggests a study of personal injury claims data for England and Wales, published online in the journal Injury Prevention.
As most of these claims involved unrestrained dogs in non-residential locations, mandating lead use on highways and in public spaces should now be explored to boost public safety, urge the researchers.
The latest ...
Breastfeeding may lower mums’ later life depression/anxiety risks for up to 10 years after pregnancy
2026-01-09
Breastfeeding may lower mothers’ later life risks of depression and anxiety for up to 10 years after pregnancy, suggest the findings of a small observational study, published in the open access journal BMJ Open.
The observed associations were apparent for any, exclusive, and cumulative (at least 12 months) breastfeeding, the study shows.
Breastfeeding is associated with lower risks of postnatal depression and anxiety, but it’s not clear if these lowered risks might persist in the longer term, say the researchers.
To find out, they tracked the breastfeeding behaviour ...
Study finds more than a quarter of adults worldwide could benefit from GLP-1 medications for weight loss
2026-01-09
The worldwide prevalence of obesity has more than doubled in the last three decades, bringing with it an increase in weight-related diseases like diabetes, cardiovascular disease, and cancers. This public health crisis strains global healthcare systems and economies, but a new study co-led by investigators from Mass General Brigham could inform strategic programs to make GLP-1 medications part of the solution.
Mass General Brigham researchers and collaborators from Washington University School of Medicine in St. Louis ...
Hobbies don’t just improve personal lives, they can boost workplace creativity too
2026-01-09
As millions of us embark on New Year pledges to eat better, exercise more and learn something new, research published today suggests hobbies could do more than improve your personal life, they could make you better at work.
The study by researchers from the University of East Anglia (UEA) and Erasmus University Rotterdam explored how ‘leisure crafting’ - intentionally shaping your free time through goal setting, learning and connection - does not just boost well-being outside the office but can spill over into creativity, engagement, and meaning at work, especially for ...