Global Ocean Heat Temperatures Break Record in 2025: A Comprehensive Analysis of Thermodynamic Drivers, Regional Anomalies, and Biological Cascades

Abstract

In the annals of climate science, 2025 will be recorded not merely as another year of broken records, but as a pivotal moment where the deep thermodynamic inertia of the planetary system revealed its inexorable momentum. According to a landmark international analysis involving over 55 scientists from 31 institutions, the Earth’s oceans absorbed an additional 23 Zettajoules of heat in 2025 compared to the previous record set in 2024. This accumulation, equivalent to approximately 37 times the total annual energy consumption of the global human economy, marks the ninth consecutive year of record-breaking ocean heat content (OHC). While the surface of the ocean (Sea Surface Temperature, or SST) showed signs of moderation due to a transition toward La Niña conditions—ranking "only" third warmest in the latter half of the year—the integrated thermal energy of the upper 2,000 meters continued to spike. This divergence between surface weather and deep-ocean climate highlights the profound decoupling of atmospheric variability from the structural warming of the biosphere. This report provides an exhaustive examination of the 2025 data, synthesizing inputs from the Institute of Atmospheric Physics (IAP), NOAA, and the Copernicus Climate Change Service. It explores the contentious debate surrounding aerosol termination shock, the technical triumphs of the Deep Argo array, and the catastrophic biological feedbacks observed from the lice-infested fjords of Norway to the bleached coral ramparts of the Great Barrier Reef. The findings underscore a critical reality: the ocean is not just warming; it is undergoing a fundamental state change, symbolized poignantly by the "shrimp soldiers and crab generals" of Chinese mythology—guardians of the deep now crumbling under the dual pressures of thermal stress and acidification.

1. The Thermodynamic Imperative: Earth’s Energy Imbalance and the Ocean Sink

To understand the magnitude of the 2025 record, one must first descend from the chaotic variability of the atmosphere into the dense, slow-moving physics of the global ocean. The story of 2025 is fundamentally a story of the Earth's Energy Imbalance (EEI), the net difference between the solar energy absorbed by the planet and the thermal infrared energy radiated back into space.

1.1 The Physics of Heat Uptake

The Earth is currently in a state of radiative disequilibrium. Greenhouse gases—principally carbon dioxide, methane, and nitrous oxide—act as a radiative blanket, intercepting longwave radiation emitted by the surface and re-emitting it downward. This trapped energy must be stored within the Earth system. The laws of thermodynamics dictate that the ocean, with its immense mass and high specific heat capacity, must act as the primary reservoir.

Water requires approximately 4,184 Joules of energy to raise the temperature of one kilogram by one degree Celsius—a heat capacity roughly four times that of air.¹ When combined with the fact that the ocean's mass is approximately 270 times greater than that of the atmosphere, the result is that the ocean absorbs more than 90% of the excess heat trapped by anthropogenic forcing.² In 2025, this uptake continued at an accelerated rate, confirming that the planetary heating mechanism remains unabated despite short-term fluctuations in surface weather patterns.⁴

The implications of this storage are profound. The atmosphere has a short memory; heat stored there can be radiated away or dissipated relatively quickly. The ocean, by contrast, has a memory spanning centuries to millennia. The 23 Zettajoules absorbed in 2025 have not disappeared; they have been mixed into the thermocline and the abyss, where they will drive thermal expansion (sea-level rise), alter circulation patterns, and provide a continuous source of heat to the atmosphere during future El Niño events.⁵

1.2 The Zettajoule Scale

The unit "Zettajoule" (ZJ)—10 to the power of 21 Joules—is difficult to conceptualize but essential for grasping the scale of the 2025 anomaly.

• Planetary Scale: The 23 ZJ increase in 2025 represents an energy injection roughly equivalent to detonating hundreds of millions of Hiroshima-sized atomic bombs within the ocean in a single year.

• Economic Scale: It is approximately 37 to 40 times the total primary energy consumption of the entire human civilization in 2023 (~620 Exajoules).²

• Physical Scale: It is enough energy to boil away 2.3 billion Olympic-sized swimming pools.⁸

This immense quantity of energy suggests that the heating of the planet is not a marginal effect but a dominant physical forcing, overwhelming natural variability. The consistency of this uptake—breaking records for nine consecutive years—indicates that the "signal" of climate change has completely emerged from the "noise" of natural variability in the ocean domain.¹

1.3 Stratification and the Stability Trap

A critical, often overlooked consequence of this warming is the stabilization of the water column. As the upper ocean warms, it becomes less dense than the deeper, colder water. This increases the density gradient, or stratification, between the layers.⁹

In 2025, stratification indices reached record highs globally. This "capping" of the ocean has severe thermodynamic and biological consequences:

1. Suppressed Mixing: The stable surface layer acts as a lid, preventing wind and waves from mixing deep, nutrient-rich water up to the sunlit zone where phytoplankton grow. This starvation of the base of the food web was evident in 2025 in reduced primary productivity in several subtropical gyres.¹⁰

2. Heat Trapping: Conversely, stratification prevents surface heat from penetrating effectively into the deep ocean in some regions, causing the surface layer to overheat disproportionately. This intensifies "marine heatwaves," creating surface conditions that are lethal to corals and other shallow-water organisms.⁹

3. Deoxygenation: The barrier prevents oxygen from the atmosphere from mixing down into the interior, expanding Oxygen Minimum Zones (OMZs) and suffocating deep-water species.⁹

2. Metrology of the Abyss: How We Measured the 2025 Record

Establishing that the ocean warmed by exactly 23 Zettajoules is a triumph of modern metrology. Unlike the atmosphere, where weather stations have existed for centuries, the ocean interior was largely a "black box" until the turn of the millennium. The 2025 report relies on a sophisticated synthesis of autonomous robotics, satellite telemetry, and historical data reconstruction.

2.1 The Argo Array: Eyes in the Deep

The backbone of the 2025 assessment is the Argo program. Initiated in roughly 2000, Argo has revolutionized oceanography by deploying a fleet of nearly 4,000 robotic profiling floats.¹¹

Operational Mechanism:

Each Argo float operates on a programmed ten-day cycle. It drifts passively at a "parking depth" of 1,000 meters, carried by slow-moving currents. Every ten days, the float activates an internal bladder to change its buoyancy, descending to 2,000 meters. From this depth, it ascends to the surface, measuring temperature, salinity, and pressure continuously. Upon breaching the surface, it transmits the data profile to satellites before sinking back to its parking depth.11

2025 Status:

In 2025, the Argo array provided near-global coverage of the upper 2,000 meters. However, the program faced significant challenges. A pause in the deployment of certain Conductivity-Temperature-Depth (CTD) sensors (specifically the SBE 41/41CP series) was necessitated by the discovery of drift in salinity measurements in previous years, requiring complex post-processing corrections to ensure data fidelity.13 The 2025 dataset includes these rigorous quality control measures, ensuring that the reported warming is a physical reality and not an instrumental artifact.

2.2 Deep Argo and the Abyssal Blind Spot

One of the limitations of the standard Argo array is its depth ceiling of 2,000 meters. The ocean, however, averages nearly 4,000 meters in depth. To address this, the "Deep Argo" mission accelerated its deployment in 2025. These specialized floats, encased in pressure-resistant glass spheres, can dive to 6,000 meters.¹⁴

Data from pilot Deep Argo arrays in the Southwest Pacific and North Atlantic revealed that the abyss is not immune to warming. While the magnitude of warming in the deep ocean (below 2,000m) is smaller than in the upper layers, the immense volume of water involved means that even millidegree changes represent significant heat storage.¹⁵ The 2025 report estimates that the layers below 2,000 meters accounted for approximately 8% of the total heat gain, a critical component often missed in surface-only analyses.¹⁵

2.3 Reconstructing the Past: IAP vs. NOAA

To declare 2025 a "record," scientists must compare it to a historical baseline. This requires reconstructing ocean temperatures from the pre-Argo era (1950s-1990s), when data relied on sporadic ship measurements using buckets (which cooled by evaporation before measurement) and Expendable Bathythermographs (XBTs, which had fall-rate errors).

Two primary groups provided the estimates for the 2025 report:

1. IAP/CAS (China): The Institute of Atmospheric Physics uses a dynamic interpolation method that utilizes knowledge of ocean circulation to fill gaps between sparse historical observations. This method typically captures more heat in dynamic regions like the Kuroshio Extension and Gulf Stream.¹⁶

2. NOAA/NCEI (USA): Uses a different statistical approach to mapping and bias correction.¹⁷

Despite these methodological differences, both groups converged on the same conclusion for 2025: the ocean is warming at an accelerating rate. The IAP analysis reported a 23 ZJ increase, while NOAA's preliminary figures were consistent with this range, confirming the robustness of the trend across independent datasets.²

3. The 2025 Anomaly: Divergence of Surface and Depth

A defining characteristic of the 2025 climate year was the decoupling of Sea Surface Temperature (SST) records from Ocean Heat Content (OHC) records. While OHC smashed previous highs, SSTs moderated, creating a complex narrative that requires careful dissection.

3.1 The Surface Signal: Transition to La Niña

The years 2023 and 2024 were dominated by a strong El Niño event, which releases stored ocean heat into the atmosphere, spiking global surface temperatures. By mid-2025, however, the Pacific Ocean transitioned into a neutral phase and then toward a weak La Niña.²⁰

The La Niña Mechanism:

During La Niña, trade winds in the Pacific intensify, blowing from east to west. This pushes warm surface water toward Indonesia and Australia, allowing cold, deep water to upwell in the Eastern Equatorial Pacific. This upwelling acts as a planetary "air conditioner," cooling the global average surface temperature.5

Consequently, while June and August 2025 were still exceptionally warm by historical standards (ranking 3rd warmest on record), they did not break the absolute monthly records set during the El Niño peak of 2023/2024.¹⁷ This led to some public confusion, as surface weather appeared to "cool" slightly relative to the previous year.

3.2 The Subsurface Reality: The Heat Pump

However, the cooling of the surface during La Niña is a mask. The heat does not leave the Earth system; it is merely redistributed. The strengthened trade winds that cool the surface do so by burying the warm water in the Western Pacific Warm Pool. The heat is mechanically pumped downward, into the 100-300 meter layer.⁵

This mechanism explains the apparent paradox of 2025:

• Surface: Cooler anomalies in the Eastern Pacific.²⁰

• Subsurface: Massive heat accumulation in the Western Pacific and Indian Ocean.¹⁹

• Total: A net increase of 23 ZJ in total heat content.

The 2025 data confirms that La Niña years are actually highly efficient at storing heat in the ocean, effectively recharging the battery for the next El Niño event.¹

3.3 Vertical Distribution of Heat

The detailed analysis by Cheng et al. and the Copernicus Marine Service provides a granular breakdown of where the 2025 heat was stored ¹⁵:

• 0–300 Meters (40%): The surface mixed layer and upper thermocline absorbed the largest fraction. This layer is most chemically active and biologically productive.

• 300–700 Meters (24%): This intermediate layer showed significant warming, particularly in the Southern Ocean mode waters.

• 700–2000 Meters (28%): The warming of this deep layer is concerning because it is isolated from the atmosphere. Heat stored here is "locked in" for decades to centuries.

• Below 2000 Meters (8%): Warming in the abyss was detected primarily in the Antarctic Bottom Water formation regions, signaling a slowdown in the global overturning circulation.

Table 1: 2025 Global Climate Indicators

Indicator	2025 Status	Comparison to Record	Primary Driver
Ocean Heat Content (0-2000m)	Record High (+23 ZJ)	+16-23 ZJ vs 2024	GHG Forcing + La Niña Heat Burial
Sea Surface Temperature (SST)	3rd Warmest	Cooler than 2023/2024	Transition to La Niña
Global Surface Air Temp	Top 3	Likely 2nd or 3rd	Residual El Niño heat + GHGs
Stratification Index	Record High	Highest on record	Surface warming > Deep warming
Sea Level Rise Rate	~4.5 mm/yr	Accelerating	Thermal Expansion + Ice Melt

4. The Aerosol Forcing Controversy: A Termination Shock?

A significant scientific debate dominating the 2025 analysis was the role of reduced shipping emissions in amplifying ocean warming. This hypothesis, often termed "Termination Shock," postulates that the removal of reflective pollution has unmasked the full ferocity of greenhouse gas warming.

4.1 IMO 2020 and the Disappearing Ship Tracks

In January 2020, the International Maritime Organization (IMO) implemented regulation IMO 2020, mandating a reduction in the sulfur content of marine fuel oil from 3.5% to 0.5%.²³ Sulfur dioxide emissions from ships previously acted as a potent cooling agent. The sulfate particles served as Cloud Condensation Nuclei (CCN), brightening low-level marine stratocumulus clouds and creating highly reflective "ship tracks" visible from space.

When the regulations took effect, these tracks largely vanished. The theory posits that the resulting decrease in planetary albedo allowed significantly more solar radiation to reach the dark ocean surface, particularly in high-traffic shipping corridors like the North Atlantic and North Pacific.²⁴

4.2 The Hansen Hypothesis vs. The Consensus

In 2025, this debate came to a head with the publication of conflicting assessments.

• The "High Sensitivity" View: A group led by James Hansen argued that the reduction in aerosols resulted in a radiative forcing as high as 0.5 Watts per square meter (W/m²), significantly higher than standard IPCC estimates. They pointed to the exceptional heat anomalies in the North Atlantic (a major shipping route) as direct evidence. They argued that the 2025 heat spike was a "smoking gun" validating high climate sensitivity.²⁶

• The "Moderate" View: Other studies, utilizing machine learning to analyze satellite data, estimated the forcing to be smaller, around 0.1 to 0.2 W/m² globally. These researchers argued that while the local effect in shipping lanes was real, it was insufficient to explain the global surge in OHC. They attributed the bulk of the 23 ZJ gain to the steady accumulation of greenhouse gases and natural variability (such as the lingering effects of the 2023/24 El Niño).²⁸

4.3 The Red Sea Natural Experiment

A serendipitous "natural experiment" occurred in 2024 and 2025, providing crucial data for this debate. Due to geopolitical conflict in the Red Sea, global shipping was massively rerouted around the Cape of Good Hope (South Africa). This moved thousands of ships from the confined Red Sea to the pristine, aerosol-poor atmosphere of the South Atlantic.³⁰

Researchers at Florida State University analyzed this shift and found that even with the cleaner IMO 2020 fuels, the sudden influx of ships into the pristine South Atlantic created a measurable "cloud brightening" effect, although 67% weaker than it would have been with old fuels. This nuanced finding suggested that while aerosol-cloud interactions are potent, the "termination shock" of IMO 2020 was likely a contributing factor—an amplifier—rather than the primary driver of the 2025 heat records.³⁰

The consensus in the 2025 reports is that aerosol reduction likely added a "boost" of 0.05°C to 0.1°C to global temperatures, explaining the extreme sharpness of the recent rise, but the foundation of the heat remains CO2.³¹

5. Regional Heat Dynamics: The Geography of Stress

While the global average tells a story of steady warming, the regional manifestations in 2025 were acute and often catastrophic. The ocean did not warm uniformly; heat pooled in specific "hotspots" driven by atmospheric blocking patterns and ocean circulation changes.

5.1 The North Atlantic and Norwegian Sea: The Aquaculture Crisis

The North Atlantic has been the epicenter of surface warming anomalies for several years. In 2025, this warmth penetrated the Norwegian Sea, creating a marine heatwave with devastating economic consequences.

The Mechanism:

A persistent high-pressure system over Scandinavia in mid-2025, combined with the background warming of the Atlantic Inflow, caused water temperatures in the fjords to soar. This created ideal incubation conditions for Lepeophtheirus salmonis, the salmon louse.33

The Biological Explosion:

Salmon lice are ectoparasitic copepods whose reproductive cycle is highly temperature-dependent. In cooler waters, their lifecycle is slow. In the record warmth of 2025, it accelerated exponentially.

• The Numbers: In August 2025, lice counts in Northwest Norway reached the highest levels ever recorded. Researchers calculated that in the region north of Kvaløya alone, 60 million adult female lice were producing 105 million larvae per hour.³³

• The Impact: This biological explosion overwhelmed the aquaculture industry's defenses. Thermal delousing treatments became less effective as the fish were already stressed by low oxygen levels (a side effect of the warm water). The result was mass mortality events and emergency early harvests, costing the Norwegian economy billions and highlighting the vulnerability of food systems to ocean warming.³⁵

5.2 The North Pacific: The "Blob" Becomes Permanent

In the North Pacific, the phenomenon known as "The Blob"—a mass of warm water created by a lack of wind cooling—re-emerged with ferocity in 2025. Despite the La Niña transition, the Northeast Pacific experienced its fourth-largest marine heatwave on record.³⁶

Ecological Disruption:

The persistence of this heat since 2019 has led to a "tropicalization" of the ecosystem.

• Species Migration: In 2025, warm-water species such as ocean sunfish and certain tuna species were sighted as far north as the Gulf of Alaska, while cold-water keystone species like Pacific cod continued to retreat.³⁷

• Kelp Forest Collapse: The heatwave sustained the population of purple sea urchins (which thrive in warmer, bacteria-rich waters) while stressing the bull kelp forests. This has locked large areas of the California Current into an "urchin barren" state, a phase shift that appears increasingly irreversible.³⁸

5.3 The Southern Ocean: The Melt from Below

The Southern Ocean absorbed a disproportionate amount of the heat in the 700-2000m layer.¹⁹ This is critical because the Antarctic ice shelves extend into this depth range.

• Basal Melt: In 2025, data confirmed that Circumpolar Deep Water (CDW), now warmer than ever, was intruding onto the continental shelves of West Antarctica. This warm water melts the ice shelves from below, destabilizing the buttressing effect they provide to the continental glaciers.

• Sea Ice: While Antarctic sea ice extent showed high variability, the heat content of the water column ensures that recovery to 20th-century norms is physically impossible in the near term.¹⁷

6. Biological Catastrophes: The Crumbling Palace

The 2025 report by the IAP featured a cover illustration depicting "shrimp soldiers and crab generals" from the Chinese classic Journey to the West.² In the novel, these are the mighty guardians of the Dragon King. In the report, they are depicted as sick and crumbling. This metaphor was chosen to highlight the dual threat of warming and acidification facing calcifying organisms.

6.1 The "Shrimp Soldier" Physiology

Marine ectotherms (cold-blooded animals) like shrimp, crabs, and fish are governed by the Metabolic Index. Their metabolic rate increases with temperature (typically doubling for every 10°C rise), meaning their demand for oxygen rises. However, the solubility of oxygen in seawater decreases as temperature rises.

The Metabolic Squeeze:

In 2025, vast areas of the ocean crossed a threshold where the oxygen supply could no longer meet the metabolic demand of these species.

• Deoxygenation: The stratification observed in 2025 expanded the Oxygen Minimum Zones (OMZs). "Shrimp soldiers" and other crustaceans were forced into narrower, shallower habitable zones, increasing competition and predation risk.⁴⁰

• Acidification: Simultaneously, the ocean absorbed approximately 25% of the anthropogenic CO2 emitted in 2025. This lowered the pH, reducing the saturation state of aragonite, the mineral crabs and shrimp use to build their shells. The 2025 report highlights that these organisms are effectively expending more energy to build weaker armor in water that is suffocating them.²

6.2 The Fourth Global Coral Bleaching Event (GCBE4)

The most visible casualty of the 2025 heat was the world's coral reefs. The Fourth Global Coral Bleaching Event, which began in 2023, extended through 2025, becoming the longest and most widespread in history.

The Great Barrier Reef (GBR):

2025 marked the sixth mass bleaching event on the GBR since 2016. What made 2025 unique was the cumulative stress.

• Back-to-Back Bleaching: For only the second time in history, the GBR bleached in consecutive years (2024 and 2025). Corals that survived 2024 had depleted energy reserves and succumbed rapidly in 2025.⁴²

• Mortality Statistics: Surveys by the Australian Institute of Marine Science (AIMS) found that hard coral cover declined by 14% to 30% across the Northern and Central regions. In the worst-hit sector between Cooktown and Cape York, 41% of reefs showed high to very high bleaching prevalence.⁴³

• Degree Heating Weeks (DHW): The metric for thermal stress, DHW, accumulated to unprecedented levels. Many reefs exceeded 8 DHW, a threshold where mortality becomes likely, for months on end.⁴⁵

The "palace" of the coral reef is indeed crumbling. The 2025 data suggests that for many reefs, the interval between heatwaves is now shorter than the recovery time required (10-15 years), signaling a functional collapse of the ecosystem.⁴⁶

7. Atmospheric and Cryospheric Feedbacks: The Storms of 2025

The ocean is the engine of the global weather system. By adding 23 Zettajoules of fuel to this engine, the climate system in 2025 produced weather events of startling intensity.

7.1 The Moisture Pump and Atmospheric Rivers

The Clausius-Clapeyron relation dictates that for every 1°C of warming, the atmosphere can hold 7% more water vapor. The record ocean heat of 2025 supercharged the global hydrological cycle.

• Mechanism: Warmer SSTs led to increased evaporation. This moisture was transported by atmospheric rivers, dumping record rainfall on regions like Southeast Asia and the US West Coast. The floods in Thailand and Vietnam in late 2025 were directly attributed to the excessive moisture load derived from the overheated South China Sea and Indian Ocean.⁴⁷

• Hurricane Intensification: While the total number of hurricanes in the Atlantic was moderated by El Niño/La Niña shear factors, the storms that did form underwent "rapid intensification." The deep layer of warm water (high OHC) prevented the usual "cold wake" feedback, where a storm churns up cold water that limits its own strength. In 2025, storms intensified right up to landfall, fueled by the 100-meter deep reservoir of warm water.⁴⁸

7.2 Accelerating Sea Level Rise

The 23 ZJ of heat has a direct physical volume. As water warms, it expands (thermosteric expansion).

• 2025 Contribution: Thermal expansion accounted for approximately 40-50% of the sea-level rise observed in 2025. The rate of global mean sea-level rise has accelerated from roughly 2.1 mm/year in the 1990s to over 4.5 mm/year in the 2025 period.⁵⁰

• The steric component: The IAP report highlighted that the "steric" (volume) sea level rise is tracking the upper bounds of climate model projections, threatening low-lying island nations with inundation even without catastrophic ice sheet collapse.⁵⁰

8. Conclusion: The Inertia of a Warming World

The "shrimp soldiers" on the cover of the 2025 Ocean Heat Report are a warning. They represent a biosphere pushed beyond its evolutionary limits by a rate of change that has no geological precedent.

The accumulation of 23 Zettajoules of heat in a single year—during a La Niña transition—dismantles the argument that global warming has "paused" or "slowed." The divergence between the slightly cooler surface temperatures and the record-breaking deep ocean heat content in 2025 serves as a lesson in the physics of the Earth system: the surface is volatile, but the ocean is the true keeper of the climate record.

The data from 2025 confirms that the "buffer capacity" of the ocean comes at a steep price. The heat we have hidden in the deep is now doing work: it is melting ice shelves from below, expanding the water column to drown coastlines, powering storms of unprecedented wetness, and dismantling the calcium carbonate architecture of marine life.

As we look toward 2026, the thermal inertia of the ocean ensures that this warming is locked in for centuries. Even if greenhouse gas emissions were to cease today, the 23 Zettajoules absorbed in 2025 would not vanish. They will circulate through the global ocean for a millennium. The challenge now is not merely mitigation, but adaptation to a high-energy ocean that has become fundamentally different from the one human civilization grew up beside.

Key Data Summary: 2025 Ocean Heat Record

Metric	Value / Description	Impact	Source
Total Heat Gain (2025)	+23 Zettajoules (upper 2000m)	Equivalent to ~37 years of global energy use	2
Global Ranking	1st (Highest on record)	9th consecutive record year	1
0-300m Heat Uptake	~40% of total	Intensifies surface storms & marine heatwaves	15
SST Global Rank	3rd (Behind 2023, 2024)	Masked by La Niña upwelling	17
Coral Impact	41% of Northern GBR Reefs	High bleaching prevalence (GCBE4)	43
Aquaculture Impact	60 Million female lice	Record infestation in Norway	34
Sea Level Rise Rate	~4.5 mm/year	Accelerated by thermal expansion	50
Aerosol Forcing	~0.1 - 0.5 W/m²	Secondary amplifier (Termination Shock debate)	27

Works cited

1. In 2025, the Ocean Stored a Record-Breaking Amount of Heat, Again, accessed January 9, 2026, https://eos.org/research-and-developments/in-2025-the-ocean-stored-more-heat-than-weve-ever-recorded

2. Ocean temperatures reached another record high in 2025, accessed January 9, 2026, https://www.eurekalert.org/news-releases/1111665

3. Ocean Warming - Earth Indicator - NASA Science, accessed January 9, 2026, https://science.nasa.gov/earth/explore/earth-indicators/ocean-warming/

4. Distinctive Pattern of Global Warming in Ocean Heat Content in - AMS Journals, accessed January 9, 2026, https://journals.ametsoc.org/view/journals/clim/38/9/JCLI-D-24-0609.1.xml

5. Where does global warming go during La Niña? | NOAA Climate.gov, accessed January 9, 2026, https://www.climate.gov/news-features/blogs/enso/where-does-global-warming-go-during-la-nina

6. Earth's Oceans Just Hit Their Hottest Level Ever Recorded - SciTechDaily, accessed January 9, 2026, https://scitechdaily.com/earths-oceans-just-hit-their-hottest-level-ever-recorded/

7. accessed January 9, 2026, https://www.mercator-ocean.eu/sea-surface-and-deeper-water-temperatures-reached-a-new-record-high-in-2024/#:~:text=patterns%20for%202024.-,Cheng%2C%20L.%2C%20von%20Schuckmann%2C%20K.%2C%20et,total%20electricity%20generation%20in%202023.

8. 2023 the hottest year for ocean - Ocean and Climate, accessed January 9, 2026, http://www.ocean.iap.ac.cn/pages/detail/detail.html?type=n&id=8334a01b42a945dfab874fbbb8e3942a&languageType=en&navAnchor=news

9. New Record Ocean Temperatures and Related Climate Indicators in 2023, accessed January 9, 2026, https://www.iapjournals.ac.cn/aas/article/doi/10.1007/s00376-024-3378-5

10. (PDF) Ocean heat content in 2024 - ResearchGate, accessed January 9, 2026, https://www.researchgate.net/publication/390699599_Ocean_heat_content_in_2024

11. Argo Program - Global Ocean Monitoring and Observing, accessed January 9, 2026, https://globalocean.noaa.gov/research/argo-program/

12. Argo floats, accessed January 9, 2026, https://argo.ucsd.edu/

13. Status Updates - Argo floats, accessed January 9, 2026, https://argo.ucsd.edu/category/status/

14. Deep Argo Mission, accessed January 9, 2026, https://argo.ucsd.edu/expansion/deep-argo-mission/

15. New Paper Co-Authored by MOi Oceanographers Reports Record-Breaking Ocean Heat Content Levels In 2023, accessed January 9, 2026, https://www.mercator-ocean.eu/new-paper-co-authored-by-moi-oceanographers-reports-record-breaking-ocean-heat-content-levels-in-2023/

16. research group. Model simulations were used to guide the mapping from point measurements to the grid (EnOI with dynamical ensemble, see Cheng&Zhu 2016 for approach details), while sampling error was estimated by sub-sampling the ARGO data at the locations of the earlier observations (Cheng et al. 2017). - Ocean and Climate, accessed January 9, 2026, http://www.ocean.iap.ac.cn/pages/dataService/dataService.html?navAnchor=dataService

17. Assessing the Global Climate in June 2025 - National Centers for Environmental Information, accessed January 9, 2026, https://www.ncei.noaa.gov/news/global-climate-202506

18. Monthly Climate Reports | Global Climate Report | May 2025 | National Centers for Environmental Information (NCEI), accessed January 9, 2026, https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202505

19. Record High Temperatures in the Ocean in 2024, accessed January 9, 2026, https://www.iapjournals.ac.cn/aas/article/doi/10.1007/s00376-025-4541-3

20. Climate Prediction Center: ENSO Diagnostic Discussion - NOAA, accessed January 9, 2026, https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml

21. Assessing the Global Temperature and Precipitation Analysis in August 2025 | News, accessed January 9, 2026, https://www.ncei.noaa.gov/news/global-climate-202508

22. (PDF) Ocean heat content in 2023 - ResearchGate, accessed January 9, 2026, https://www.researchgate.net/publication/379592536_Ocean_heat_content_in_2023

23. 2025 News & Events: Scientists turn to artificial intelligence to assess the warming effect of reduced pollution - NOAA CSL, accessed January 9, 2026, https://csl.noaa.gov/news/2025/423_0113.html

24. August 2025 Temperature Update - Berkeley Earth, accessed January 9, 2026, https://berkeleyearth.org/august-2025-temperature-update/

25. Has Reducing Ship Emissions Brought Forward Global Warming?, accessed January 9, 2026, https://www.globalhealth.ox.ac.uk/research/publications/2021368

26. The Acid Test: Global Temperature in 2025 - Columbia University, accessed January 9, 2026, https://www.columbia.edu/~jeh1/mailings/2025/Acid.Test.20Feb2025.pdf

27. Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?, accessed January 9, 2026, https://www.tandfonline.com/doi/full/10.1080/00139157.2025.2434494

28. Regional variability of aerosol impacts on clouds and radiation in global kilometer-scale simulations - ACP, accessed January 9, 2026, https://acp.copernicus.org/articles/25/7789/2025/

29. Surface temperature effects of recent reductions in shipping SO2 emissions are within internal variability - ACP, accessed January 9, 2026, https://acp.copernicus.org/articles/25/4443/2025/acp-25-4443-2025.pdf

30. A global shipping detour just revealed a hidden climate twist - ScienceDaily, accessed January 9, 2026, https://www.sciencedaily.com/releases/2025/11/251125081914.htm

31. Analysis: What are the causes of recent record-high global temperatures? - Eco-Business, accessed January 9, 2026, https://www.eco-business.com/news/analysis-what-are-the-causes-of-recent-record-high-global-temperatures/

32. Indicators of Global Climate Change 2024: annual update of key indicators of the state of the climate system and human influence - ESSD Copernicus, accessed January 9, 2026, https://essd.copernicus.org/articles/17/2641/2025/

33. Western Norway hit by strongest marine heatwave in three decades - WEAREAQUACULTURE, accessed January 9, 2026, https://weareaquaculture.com/regions/europe/western-norway-hit-by-strongest-marine-heatwave-in-three-decades

34. "Perfect Storm" under the midnight sun triggered marine heatwave and explosion of salmon lice - Climate Futures, accessed January 9, 2026, https://www.climatefutures.no/en/perfect-storm-under-the-midnight-sun-triggered-marine-heatwave-and-explosion-of-salmon-lice/

35. 2024 marked most challenging sea lice season in more than a decade for Norway, report finds, accessed January 9, 2026, https://www.globalseafood.org/advocate/2024-marked-most-challenging-sea-lice-season-in-more-than-a-decade-for-norway-report-finds/

36. Northeast Pacific endures fourth-largest marine heat wave on record - Mongabay, accessed January 9, 2026, https://news.mongabay.com/short-article/2025/09/northeast-pacific-endures-fourth-largest-marine-heat-wave-on-record/

37. World's longest marine heat wave upended ocean life across the Pacific - University of Western Australia, accessed January 9, 2026, https://www.uwa.edu.au/news/article/2025/august/worlds-longest-marine-heat-wave-upended-ocean-life-across-the-pacific

38. The heatwave that shattered ecosystems, starved whales, and drove fish north, accessed January 9, 2026, https://www.sciencedaily.com/releases/2025/07/250720034018.htm

39. The California Current Marine Heatwave Tracker - Blobtracker | Integrated Ecosystem Assessment - NOAA, accessed January 9, 2026, https://www.integratedecosystemassessment.noaa.gov/regions/california-current/california-current-marine-heatwave-tracker-blobtracker

40. Record ocean warming fuels sea level and storm risks - Oceanographic Magazine, accessed January 9, 2026, https://oceanographicmagazine.com/news/record-ocean-warming-fuels-sea-level-and-storm-risks/

41. Multimodal Cross-Cultural Communication in Black Myth: Wukong (2024) - ResearchGate, accessed January 9, 2026, https://www.researchgate.net/publication/395323219_Multimodal_Cross-Cultural_Communication_in_Black_Myth_Wukong_2024

42. Coral Bleaching 2026: What It Means for the Reef - Great Barrier Reef Foundation, accessed January 9, 2026, https://www.barrierreef.org/the-reef/threats/coral-bleaching

43. Annual Summary Report of Coral Reef Condition 2024/25 | AIMS, accessed January 9, 2026, https://www.aims.gov.au/monitoring-great-barrier-reef/gbr-condition-summary-2024-25

44. Coral bleaching events | AIMS - The Australian Institute of Marine Science, accessed January 9, 2026, https://www.aims.gov.au/research-topics/environmental-issues/coral-bleaching/coral-bleaching-events

45. NOAA Coral Reef Watch Current Global Bleaching: Status Update & Data Submission, accessed January 9, 2026, https://coralreefwatch.noaa.gov/satellite/research/coral_bleaching_report.php

46. Great Barrier Reef suffers largest annual coral decline, and other nature and climate news, accessed January 9, 2026, https://www.weforum.org/stories/2025/08/great-barrier-reef-coral-decline-nature-climate-news/

47. World's oceans set new heat record in 2025: Study, accessed January 9, 2026, https://www.ap7am.com/en/117960/worlds-oceans-set-new-heat-record-in-2025-study

48. Ocean Heat - Global Ocean Monitoring and Observing Program - NOAA, accessed January 9, 2026, https://globalocean.noaa.gov/the-ocean/ocean-heat/

49. Onset of 2025 Atlantic Niña: What it means for the Atlantic hurricane season (updated), accessed January 9, 2026, https://ocean2climate.org/2025/06/07/onset-of-2025-atlantic-nina-what-it-means-for-the-atlantic-hurricane-season/

50. 2025 set to be second or third warmest year on record, continuing exceptionally high warming trend - World Meteorological Organization WMO, accessed January 9, 2026, https://wmo.int/news/media-centre/2025-set-be-second-or-third-warmest-year-record-continuing-exceptionally-high-warming-trend

51. Estimating ocean heat content from the ocean thermal expansion parameters using satellite data - ESD, accessed January 9, 2026, https://esd.copernicus.org/articles/16/91/2025/