WMO declares 2025 and preceding 11 years as warmest on record, with global temps 1.44°C above pre-industrial levels. Extreme weather, including record hurricanes and floods, underscores accelerating climate change, intensifying global policy debates ahead of COP30.
Global Temperature Records Set in 2025
The World Meteorological Organization (WMO) has confirmed that the preceding 11 years, including 2025, represent the warmest temperature period since systematic climate measurements began in the mid-19th century. Analysis of eight datasets—ERA5, JRA-3Q, GISTEMP, NOAAGlobalTemp, HadCRUT5, Berkeley Earth, CMST, and DCENT—reveals 2025 as either the second or third warmest year globally. The average global surface temperature for 2025 was 1.44°C above the 1850–1900 reference period (±0.13°C uncertainty), underscoring the accelerating pace of human-induced climate change. The three-year average (2023–2025) showed a 1.48°C increase compared to pre-industrial levels, reinforcing the sustained warming trend.
Methodology and Data Sources
“The 11-year warming trend remains statistically significant, with a 95% confidence level in the observed rise.”
The WMO’s analysis combines statistical techniques and reanalysis methods to address data gaps and ensure comprehensive coverage, including polar regions. Datasets rely on weather station, ship, and buoy observations, with models like ERA5 and JRA-3Q incorporating satellite data to maintain consistent climate records. Despite methodological differences, six datasets rank 2025 as third warmest, while two place it second. This consensus reflects the scientific community’s alignment on greenhouse gas emissions as the primary driver of global temperature rise.
Ocean Heat and Climate Impacts
Ocean heat content (OHC) is a critical indicator of Earth’s energy imbalance. Between 2024 and 2025, the upper 2000 m of the global ocean absorbed approximately 23 ± 8 Zettajoules of heat, with 90% of the excess energy retained by the oceans. The 2025 global annual mean sea surface temperature (SST) was 0.49°C above the 1981–2010 baseline, ranking it third-warmest on record. Warmer ocean temperatures are linked to intensified tropical storms, prolonged droughts, and coral bleaching. The 2025 Atlantic hurricane season featured 22 named storms—the highest on record.
Extreme Weather and Human Impact
The WMO links the decade’s unprecedented warmth to a surge in extreme weather events, displacing millions and disrupting food systems. In 2025, heatwaves in Europe and South Asia caused over 15,000 excess deaths, according to the European Environment Agency. Record rainfall in East Africa led to catastrophic flooding, displacing 2.3 million people and damaging infrastructure valued at $4.2 billion. Prolonged droughts in the Horn of Africa reduced crop yields by 30% compared to the 2010–2020 average. A 12% rise in heat-related mortality globally highlights health impacts, with vulnerable populations disproportionately affected. The 2025 Australian bushfire season, driven by record temperatures and drought, burned 18.6 million hectares, an area exceeding the country’s total landmass.
Natural Variability and Human Influence
“Heatwaves in Europe and South Asia caused over 15,000 excess deaths, according to the European Environment Agency.”
Natural climate variability, such as La Niña, is acknowledged as a temporary moderating factor. In 2025, La Niña conditions contributed a 0.2°C cooling effect, explaining why some datasets ranked the year as third warmest. However, the report clarifies that natural influences cannot counteract the dominant role of human-driven greenhouse gas emissions. The 11-year warming trend remains statistically significant, with a 95% confidence level in the observed rise. Adjustments for pre-industrial baselines and uncertainties ensure the warming trend is attributed to human activities rather than natural cycles.
Policy Implications and Future Outlook
The WMO’s findings have intensified global policy discussions, with the upcoming UN Climate Conference (COP30) in Belem, Brazil, serving as a key platform for action. The WMO’s State of the Global Climate 2025 report, set for release in March 2026, will detail greenhouse gas concentrations, ocean heat, sea level rise, and high-impact climate events. The report underscores the necessity of immediate, large-scale reductions in greenhouse gas emissions to align with the Paris Agreement’s 1.5°C target. However, current national pledges under the Paris Agreement are projected to result in a 2.4–2.6°C warming by 2100. The WMO advocates for accelerated renewable energy adoption, stricter emissions regulations, and enhanced climate resilience investments, alongside improved climate data collection and early warning systems to mitigate extreme weather impacts.
- What is the significance of the 11-year period ending in 2025 for global temperatures?
The World Meteorological Organization (WMO) confirmed that the 11 years including 2025 are the warmest since systematic climate measurements began in the mid-19th century, with 2025 ranking as either second or third warmest globally. This period reflects a sustained warming trend driven by human-induced climate change. - Which datasets were used to analyze global temperature trends in 2025?
Eight datasets—ERA5, JRA-3Q, GISTEMP, NOAAGlobalTemp, HadCRUT5, Berkeley Earth, CMST, and DCENT—were analyzed to determine 2025 as the second or third warmest year. Six datasets ranked it third, while two placed it second, showing scientific consensus on the warming trend. - How much heat did the oceans absorb between 2024 and 2025?
The upper 2000 m of the global ocean absorbed approximately 23 ± 8 Zettajoules of heat between 2024 and 2025, with 90% of excess energy retained by the oceans. This underscores the role of ocean heat content as a critical indicator of Earth’s energy imbalance. - What extreme weather impacts were linked to the 2025 warming trend?
The WMO linked the decade’s warmth to record heatwaves, floods, and droughts. In 2025, heatwaves caused over 15,000 excess deaths in Europe and South Asia, while East Africa’s floods displaced 2.3 million people and damaged infrastructure worth $4.2 billion. - How did natural climate variability affect the 2025 temperature ranking?
La Niña conditions in 2025 contributed a 0.2°C cooling effect, explaining why some datasets ranked the year as third warmest. However, the report emphasizes that natural influences cannot offset the dominant role of human-driven greenhouse gas emissions in the warming trend.
