According to WMO, the high temperatures on land and sea last year helped to fuel extreme weather, including heatwaves, heavy rainfall and deadly tropical cyclones, underlining the need for early warning systems.
The World Meteorological Organization (WMO) has confirmed that 2025 ranked as one of the three warmest years on record, underscoring the relentless grip of human-driven climate change even amid natural cooling influences.
In a press release issued by the global weather organisation, the WMO announced that global average surface temperatures in 2025 were approximately 1.44°C (± 0.13°C) above the pre-industrial baseline (1850-1900). This figure comes from a consolidated analysis of eight leading international datasets, including those from NASA, NOAA, the UK Met Office, and the European Centre for Medium-Range Weather Forecasts (ECMWF).
Two datasets placed 2025 as the second-warmest year in the 176-year instrumental record, while the other six ranked it third. The absolute global average temperature for the year was estimated at around 15.08°C.
This places 2025 firmly behind 2024 (the warmest on record) and in close contention with 2023, with the past three years (2023-2025) collectively the warmest trio ever observed across all datasets. The three-year average anomaly stands at 1.48°C (± 0.13°C) above pre-industrial levels – a troubling milestone that edges perilously close to the 1.5°C limit set by the 2015 Paris Agreement (measured over longer periods). Moreover, the streak shows no signs of breaking: the past 11 years (2015-2025) are the 11 warmest on record.
Accumulation of Heat-Trapping Greenhouse Gases
WMO Secretary-General Celeste Saulo emphasized the significance of these findings in stark terms: “The year 2025 started and ended with a cooling La Niña and yet it was still one of the warmest years on record globally because of the accumulation of heat-trapping greenhouse gases in our atmosphere. High land and ocean temperatures helped fuel extreme weather – heatwaves, heavy rainfall and intense tropical cyclones, underlining the vital need for early warning systems.”
La Niña, a natural climate pattern associated with cooler Pacific waters, exerted a temporary dampening effect, particularly at the year’s bookends, making 2025 slightly cooler than the preceding years dominated by El Niño. Yet this natural variability proved no match for the overriding force of accumulated greenhouse gases from fossil fuel burning, deforestation, and industrial activities. The long-term warming trend – driven primarily by human emissions – continues unabated, with short-term fluctuations unable to reverse it.
Oceans, which absorb about 90 per cent of excess heat from global warming, told an equally alarming story. Ocean heat content in the upper 2000 meters rose by roughly 23 ± 8 zettajoules from 2024 to 2025 – equivalent to about 200 times the world’s total electricity generation in 2024. Annual mean sea surface temperatures ranked as the third-warmest on record, despite the La Niña influence. Regionally, 33 per cent of the global ocean area experienced conditions among the top three warmest since 1958, while 57 per cent ranked in the top five. Key hotspots included the tropical and South Atlantic, Mediterranean Sea, North Indian Ocean, and Southern Oceans.
These elevated ocean and land temperatures amplified extreme weather worldwide in 2025. Heatwaves scorched regions across continents, heavy rainfall triggered devastating floods, and intense tropical cyclones caused widespread destruction. The WMO stressed that such events highlight the critical importance of robust early warning systems to protect vulnerable populations.
A Continuing Crisis
The UN News coverage of the announcement reinforced these points, describing the 11-year streak of record warmth as a continuing crisis. It noted that ocean warming reflects the persistent buildup of heat in the climate system, with broad implications for marine ecosystems, weather patterns, and sea-level rise. While the full State of the Global Climate 2025 report – due in March 2026 – will provide deeper analysis of greenhouse gas concentrations, ice melt, and other indicators, the preliminary data already paints a picture of accelerating risks.
Experts view these results as a clear warning. Despite the absence of a strong El Niño boost in 2025, temperatures remained extraordinarily high, demonstrating how deeply entrenched the warming trajectory has become. Projections suggest 2026 could rank similarly – potentially among the top five warmest years – depending on whether ENSO shifts back toward neutral or El Niño conditions later in the year.
The confirmation arrives amid growing urgency for global action. With the three-year average now hovering near or at 1.5°C thresholds in some metrics, scientists warn that every fraction of a degree amplifies impacts on ecosystems, economies, and human health. The WMO called for enhanced climate monitoring, accessible data, and decisive emissions reductions to mitigate the worst outcomes.
As Celeste Saulo noted, authoritative climate information is “more important than ever before” to make Earth’s changing conditions actionable for policymakers, communities, and individuals alike. The data from 2025 serves as both a sobering record and a pressing call: the window for meaningful intervention narrows with each passing year of exceptional heat.
