RESEARCH
2025 Was Earth's Second- or Third-Warmest Year on Record -- Trackers Split on the Ranking
2025 closed as one of the three warmest years ever measured in the global instrumental record, but the exact rank depends on which agency's dataset is cited. Copernicus, NOAA, and Berkeley Earth each independently placed 2025 third-warmest, behind only 2024 and 2023, with anomalies of roughly 1.17-1.47C above their respective baselines. NASA's GISS analysis instead found 2025 statistically tied with 2023 -- within the margin of error of second place -- a split the World Meteorological Organization's own consolidated report confirms: two of eight major global datasets rank 2025 second-warmest, six rank it third. The larger trend is not in dispute: 2023-2025 is the first three-year period on record to average above the Paris Agreement's 1.5C threshold.
Findings
- WMO's consolidated analysis, combining all major international datasets, found two of eight leading global temperature datasets rank 2025 as the second-warmest year on record while the other six rank it third -- there is no single agreed ranking across the field.
- Copernicus (C3S), NOAA, and Berkeley Earth all independently rank 2025 the third-warmest year since their records began (behind 2024 and 2023), citing global mean anomalies of roughly 1.47C, 1.17C, and 1.44C above their respective pre-industrial or 20th-century baselines.
- NASA GISS found 2025 statistically tied with 2023 -- 1.19C above its 1951-1980 baseline, differing from 2023 by only hundredths of a degree -- meaning NASA's own data places 2025 within the margin of error of second place, diverging from the clear third-place finding of Copernicus, NOAA, and Berkeley Earth.
- All trackers agree on the larger signal regardless of exact rank: 2023-2025 is the first three-year span in any dataset to average above 1.5C over the 1850-1900 pre-industrial baseline, and the 10 most recent years remain the 10 warmest years on record.
Delta Engine result
↔ Divergence Detected — Δ 0.3 (threshold 0.05)
- WMO T5 92
- Copernicus C3S T5 85
- NOAA NCEI T5 85
- NASA GISS T5 68
- Berkeley Earth T4 75
Evidence quality
avg 93 · min 85 · max 95 · spread 10