Global climate agencies confirm that the past 11 years are the warmest ever recorded, with 2025 ranking as the second or third hottest year since instrumental observations began. The World Meteorological Organization’s State of the Global Climate 2025 report, issued today, says atmospheric carbon dioxide and ocean heat content reached new highs in 2025 while global surface temperatures remained slightly below 2024’s record. Antarctic and Arctic sea ice extents were among the lowest observed since 1979, and a newly featured metric — the Earth’s energy imbalance (EEI) — reached its highest level on record. Scientists warn these indicators point to a sustained, accelerating shift in the climate system with broad environmental and societal implications.
Key takeaways
- WMO report: The World Meteorological Organization’s State of the Global Climate 2025 finds the last 11 years are the warmest on record, with 2025 placing second or third by surface-temperature metrics.
- Record drivers: Atmospheric carbon dioxide concentrations and global ocean heat content both reached record highs in 2025, according to the WMO assessment.
- Earth’s energy imbalance (EEI): For the first time included in the WMO statement, EEI in 2025 was the highest since observational records began in 1960, indicating net heat accumulation.
- Ocean heat uptake: Climate analysts estimate more than 91% of excess heat since the 1970s has been absorbed by the oceans, magnifying long-term warming even when surface temperatures fluctuate.
- Sea ice lows: Antarctic and Arctic sea-ice extents in 2025 were among the lowest since 1979, contributing to polar ecosystem stress and sea-level considerations.
- Recent step change: Researchers report a clear step increase in global temperature over the last three years that is consistent with anthropogenic climate change rather than natural variability.
- Short-term ranking uncertainty: Annual surface-temperature rankings (e.g., whether 2025 is second or third warmest) are sensitive to methodological differences and short-term variability.
Background
Global temperature records rely on a network of surface, satellite and ocean measurements that together form multi-decadal time series. Over recent decades, the dominant driver of rising global temperatures has been increasing concentrations of greenhouse gases, primarily carbon dioxide from fossil-fuel combustion and land-use change. Scientists use several indicators to describe the climate state: surface air temperatures, ocean heat content, greenhouse-gas concentrations, sea-ice extent and now the Earth’s energy imbalance, which quantifies net heat gain.
Instrumental records for surface temperature extend back roughly 150 years in many datasets, while systematic ocean heat measurements have improved since the deployment of the Argo float network in the early 2000s. Polar sea ice records begin in 1979 with consistent satellite observations. These overlapping datasets allow climate scientists to detect long-term trends despite year-to-year variability caused by phenomena such as El Niño/La Niña and volcanic eruptions.
Main event
The WMO released its State of the Global Climate 2025 report today, compiling observations from national meteorological services, oceanographic programs and satellite records. The report states that surface temperatures in 2025 were marginally cooler than the unprecedented 2024 peak but that the sequence of high-temperature years continues. That sequence — 11 consecutive years of record-high temperatures — is statistically robust across several observing systems.
Crucially, the 2025 bulletin includes EEI as a headline indicator. EEI measures the imbalance between incoming solar radiation and the energy Earth radiates back to space; a positive EEI means the planet is accumulating heat. In 2025 this imbalance reached the highest measured level since the EEI record began in 1960, reflecting increased greenhouse-gas forcing and reduced outgoing longwave radiation.
Ocean heat content and atmospheric greenhouse-gas concentrations set new records in 2025. Because oceans store the bulk of the planet’s excess heat, rising ocean heat content signals long-lived warming that will continue to influence weather patterns, sea-level rise, and marine ecosystems even if surface temperatures vary year to year. Meanwhile, polar sea-ice cover remained near multi-decade lows, with both Arctic and Antarctic extents recorded among the smallest since the 1979 satellite era began.
Analysis & implications
Including EEI in a major annual climate statement shifts focus from transient surface-temperature rankings to the underlying energy accumulation driving long-term change. Surface temperature can be influenced in the short term by volcanic aerosols, El Niño/La Niña cycles and other modes of variability, but EEI integrates the net forcing trend and thus better reflects the planet’s sustained warming trajectory. Policymakers and planners should regard rising EEI as evidence that warming—and its downstream impacts—will continue to escalate unless greenhouse-gas emissions are rapidly reduced.
Because more than 90% of excess heat is taken up by the oceans, marine warming will persist and intensify. Warmer oceans expand thermally, contributing to sea-level rise, alter circulation patterns such as the Atlantic Meridional Overturning Circulation, and increase the frequency and intensity of marine heatwaves. These changes carry implications for coastal communities, fisheries and the frequency of extreme weather events linked to ocean-atmosphere interactions.
The reported step change in global temperature over the last three years suggests the climate system may be moving to a new baseline of higher mean temperatures. That raises adaptation challenges: infrastructure, agriculture and public-health systems designed for historical climate norms may be inadequate. International climate diplomacy will likely face renewed pressure to strengthen mitigation commitments, while investment in adaptation, early warning systems and resilient infrastructure will become more urgent.
Comparison & data
| Indicator | 2025 status | Reference period |
|---|---|---|
| Surface temperature rank | 2nd or 3rd hottest | Instrumental record (since ~1850) |
| Earth’s energy imbalance (EEI) | Highest since 1960 | EEI record (since 1960) |
| Ocean heat content | Record high | Argo and historical ocean data |
| Polar sea ice | Among lowest since 1979 | Satellite era (since 1979) |
The table summarizes the primary metrics highlighted by the WMO report. These indicators differ in sensitivity and temporal response: EEI and ocean heat content integrate long-term forcing, while surface temperature and sea ice can show larger interannual variability. Analysts use all metrics together to form a comprehensive picture of climate change.
Reactions & quotes
“The speed of warming, ocean heating and ice loss is deeply concerning and signals sustained change,”
Mandy Freund, climate scientist, University of Melbourne (academic)
Friend’s observation emphasizes the convergence of multiple indicators — atmosphere, ocean and cryosphere — pointing to an accelerating trend rather than isolated fluctuations.
“We appear to be entering an era where temperatures will be noticeably higher than a decade ago,”
Sarah Perkins-Kirkpatrick, climate scientist, Australian National University (academic)
Perkins-Kirkpatrick highlights the recent three-year step change in global temperature that researchers attribute primarily to anthropogenic greenhouse-gas forcing rather than natural variability.
“EEI provides a clearer picture of warming than surface temperature alone, because most excess heat goes into the ocean,”
Thomas Mortlock, climate analyst, UNSW Sydney (academic)
Mortlock’s comment explains why EEI and ocean heat content are essential for assessing the true magnitude of climate forcing beyond headline annual temperature rankings.
Unconfirmed
- Exact ranking of 2025 as second or third warmest depends on dataset choice and methodological details; different global surface temperature products may produce slightly different ordinal results.
- Attribution of the recent three-year step change to specific combinations of forcings and internal variability components remains an active area of research and has not been fully quantified in the public WMO summary.
Bottom line
The WMO’s 2025 statement underlines that the climate system is accumulating heat at an unprecedented rate in the observational record, driven by rising greenhouse-gas concentrations and reflected most clearly in ocean heat content and EEI. While annual surface-temperature rankings attract headlines, the underlying energy accumulation signals a long-lived commitment to higher temperatures, sea-level rise and more intense climate extremes.
For policymakers, the message is twofold: mitigation must be accelerated to reduce future forcing, and adaptation investment must be scaled up to manage impacts already set in motion. Scientists will continue refining attribution studies, improving ocean and EEI monitoring, and translating those metrics into actionable risk assessments for societies and ecosystems.
Sources
- Nature — State of the Global Climate 2025 coverage (media report)
- World Meteorological Organization (WMO) official website (official agency/report)
- University of Melbourne (academic institution — researcher affiliation)
- Australian National University (academic institution — researcher affiliation)
- UNSW Sydney (academic institution — researcher affiliation)