2025 Global Climate Highlights

2025 ranks third-warmest year at 1.47°C above pre-industrial levels, marking first three-year average exceeding 1.5°C as exceptional heat persists globally.

The 2025 Global Climate Highlights report reveals the year ranked as the third-warmest on record with global temperatures reaching 14.97°C—1.47°C above pre-industrial levels—marking the first time a three-year average (2023-2025) exceeded 1.5°C at 1.52°C, as exceptional heat persisted across 91% of Earth's surface despite the absence of El Niño conditions and transition to weak La Niña.

Published in January 2026 by the Copernicus Climate Change Service (C3S) and the European Centre for Medium-Range Weather Forecasts (ECMWF), the Global Climate Highlights report synthesizes ERA5 global atmospheric reanalysis data covering 1940-2025 alongside additional international datasets. The comprehensive assessment tracks global air temperature, sea surface temperature, and polar sea ice, revealing that while 2025 was 0.13°C cooler than record-breaking 2024, it remained only 0.01°C cooler than 2023, with all 11 years from 2015-2025 ranking among the 11 warmest on record. The analysis demonstrates that current global surface warming has reached approximately 1.4°C above pre-industrial levels by end of 2025, with projections suggesting the 1.5°C threshold could be crossed by decade's end if warming continues at the rate of the last 30 years.

Key Findings: Persistent Warmth Across Multiple Climate Indicators

Global Temperature Anomaly of +0.59°C Relative to 1991-2020 Average

The 2025 global average temperature of 14.97°C registered 0.59°C above the 1991-2020 baseline and 1.47°C above the 1850-1900 pre-industrial reference period. According to ERA5, 2025 ranked as the third-warmest year, marginally (0.01°C) cooler than second-warmest 2023, while 2024 remains the warmest year on record and the first year clearly exceeding 1.5°C above pre-industrial levels.

The JRA-3Q reanalysis independently confirmed 2025 as the third-warmest year with an anomaly of 1.46°C relative to 1850-1900 and absolute temperature of 14.98°C. Other international datasets (Berkeley Earth, GISTEMPv4, HadCRUT5, NOAAGlobalTempv6) are estimated to place 2025 between 1.39°C and 1.45°C above pre-industrial levels, ranking it either second or third warmest depending on the dataset.

First Three-Year Average Exceeding 1.5°C in Instrumental Record

While 2025 did not individually reach 1.5°C above pre-industrial levels, the average global temperature for 2023-2025 exceeded this threshold, registering 1.52°C for ERA5 and 1.50°C for JRA-3Q. This represents the first three-year average to surpass 1.5°C in the instrumental period, underscoring the persistence of exceptional warmth rather than a temporary spike.

The years 2023-2025 stand distinctly apart from all previous years in the observational record. Six months of 2025 exceeded 1.5°C above pre-industrial levels (January through April, plus October and November), concluding an almost continuous 21-month series at or above this threshold that began in July 2023, with July 2024 as the sole exception.

All Monthly Temperature Records Broken Over Past Three Years

January 2025 was the warmest January on record globally. March, April, and May each ranked as the second warmest for their respective months. Each month of the year except February and December was warmer than the corresponding month in any year before 2023, demonstrating the comprehensive nature of recent warming across the seasonal cycle.

Boreal winter (December 2024-February 2025) ranked as the second-warmest at 0.71°C above average, behind 2024. Spring (March-May) also ranked second-warmest at 0.59°C above average. Summer (June-August) and autumn (September-November) each ranked third-warmest for their respective seasons, cooler only than 2024 for summer and 2023 for autumn.

Exceptional Heat Persisted Across 91% of Earth's Surface

Annual surface air temperatures exceeded the 1991-2020 average across 91% of the globe in 2025, the same fraction as 2024. Nearly half of Earth's surface (48%) experienced much warmer than average temperatures exceeding the 90th percentile of the 1991-2020 climatology. Annual temperatures reached record highs over 9% of Earth's surface relative to all years since 1979 in the ERA5 dataset.

While these proportions were less extreme than 2024's figures (63% much warmer than average and 31% warmest on record), they highlight the persistence of widespread warmth. Land areas that were much warmer than average included tropical Americas, northeastern Canada, large parts of Africa, the Maritime Continent, much of Europe and extratropical Asia, plus most of Greenland and Antarctica.

Regional Temperature Patterns Reveal Polar Amplification

Temperature anomalies averaged over five latitude bands reveal notable regional differences compared to 2023 and 2024. In the tropics, the 2025 anomaly (+0.29°C) was substantially lower than 2023 (+0.53°C) and 2024 (+0.68°C), reflecting persistent neutral ENSO conditions or weak La Niña throughout 2025 rather than the strong El Niño influencing 2023-2024.

In stark contrast, polar regions showed exceptional warmth. The Antarctic region registered a record-high anomaly of +1.06°C in 2025. The Arctic anomaly of +1.37°C ranked as second-highest on record behind 2016 (+1.59°C). Northern mid-latitudes showed an anomaly of +0.84°C, lower than 2024 (+0.99°C) but identical to 2023, jointly ranking as second-highest on record. Southern mid-latitudes at +0.42°C jointly tied with 2016 as warmest on record for the region.

Global Land Areas Second-Warmest on Record at +0.86°C

Annual air temperature averaged over all global land areas reached the second warmest on record at 0.86°C above the 1991-2020 average, only 0.20°C cooler than the 2024 record and 0.01°C warmer than 2023. Record-high land temperatures occurred over western United States, eastern Greenland, northern Europe, western Russia, central Asia, eastern China, and Antarctica.

Cooler-than-average to much cooler-than-average land regions included eastern South America, parts of westernmost and southern Africa, most of India, parts of southeast Asia, and far-eastern Russia. These cooler anomalies, along with reduced tropical ocean temperatures under ENSO-neutral conditions, lowered the global average in 2025 while record or near-record warmth in most other regions partly offset this effect.

Sea Surface Temperatures Remained Third-Highest Despite La Niña Conditions

The annual average sea surface temperature for the extrapolar oceans (60°S-60°N) was 20.73°C, 0.38°C above the 1991-2020 average, ranking third-highest on record. This was 0.13°C below the 2024 record and 0.07°C below second-highest 2023, making 2025 the warmest La Niña year on record for both global air temperature and SST.

At the monthly scale, average SST ranked second-warmest from January to May (behind 2024), third-warmest from June to October (behind 2023 and 2024), and fourth-warmest in November and December (behind 2023, 2024, and 2015). About 9% of the extrapolar oceans experienced record-high annual SSTs, with 42% registering much warmer than average (above 90th percentile), underscoring continued widespread ocean warmth despite less extreme conditions than 2024's 59%.

Record-Low Global Sea Ice in February 2025

Arctic sea ice extent reached record lows for the time of year from December 2024 through March 2025, with the March annual maximum ranking lowest in the 47-year satellite record. Monthly extents remained well below average through August, ranking between second and ninth lowest for their respective months. The September annual minimum ranked 13th lowest for the month, with November ranking second lowest and December ranking lowest for the time of year.

Antarctic sea ice began 2025 near-average in January, contrasting sharply with 2023-2024's record lows. However, February's extent reached the fourth-lowest annual minimum (second-lowest in daily extent). For the remainder of the year, Antarctic sea ice remained well below average, with monthly rankings generally between third and fifth lowest. The September annual maximum ranked third lowest in the satellite record. February 2025's combination of record-low Arctic extent and much-below-average Antarctic extent resulted in the lowest global sea ice cover for any month since satellite observations began in the late 1970s.

Why This Matters: Approaching Critical Climate Thresholds

The 2025 Global Climate Highlights report provides crucial context for understanding humanity's trajectory relative to Paris Agreement targets adopted ten years ago. The finding that the three-year average for 2023-2025 exceeded 1.5°C for the first time in the instrumental record represents a significant milestone, even though breaching this threshold requires sustained long-term warming rather than individual years or short periods above the limit.

The analysis of global temperatures relative to an evolving climatological baseline rather than a fixed reference period reveals the exceptional nature of recent warmth. Only two years—1877 and 1878 during the "Great Drought" that killed an estimated 50 million people—were comparably warmer than 2024 when measured against their contemporary climate. The period 2023-2025 ranks jointly with 1899-1901 as the warmest three consecutive years relative to the evolving climate, highlighting that current conditions are unprecedented in the modern era.

The warming rate of the background climatological state has accelerated from 0.18°C per decade at the mid-point of 1979-2008 to 0.25°C per decade by end of 2025. The evolving climate warmed to 1.38°C above its 1850-1900 average by end of 2025. Three separate monitoring methods using C3S data indicate current global surface warming of approximately 1.4°C above pre-industrial levels, with the C3S global trend monitor projecting crossing of the 1.5°C level by 2029 if warming continues at the last 30 years' rate.

The WMO Global Annual to Decadal Climate Update for 2025-2029 identified an 80% chance that at least one year would replace 2024 as warmest on record, an 86% chance that at least one year would exceed 1.5°C above 1850-1900 average like 2024, and a 70% chance that the five-year average warming for 2025-2029 would surpass 1.5°C above pre-industrial levels. This projection aligns with the "early 2030s" central estimate from the IPCC AR6 report for breaching the 1.5°C threshold.

Exceptional Circumstances Behind 2023-2025 Warmth

The exceptional warmth of 2023-2025 stems from two main factors working in concert. First, accelerating human-induced climate warming reflects both faster greenhouse gas accumulation from continued emissions and reduced natural carbon uptake, plus diminished aerosol cooling including from lower emissions from East Asia since 2010. Preliminary satellite data from the Copernicus Atmosphere Monitoring Service shows column-averaged concentrations of carbon dioxide and methane, which reached record levels in 2024, continued increasing in 2025.

Second, sea surface temperatures reached exceptionally high levels across the ocean beyond what the 2023-2024 El Niño event alone would explain. A significant fraction of additional atmospheric warmth over the last three years originated from SSTs across oceanic regions other than the tropical Pacific. The 2023-2024 El Niño, while strong with a peak Oceanic Niño Index of 2.0°C, was smaller than the 2015-2016, 1997-1998, and 1982-1983 events. Additionally, 2024 and 2025 showed slower transitions from El Niño toward neutral and weak La Niña conditions than typically occurs.

Other factors potentially influencing temperatures either directly or by enhancing SST anomalies include atmospheric circulation anomalies affecting cloud amounts and air-sea interaction; lower sulphur dioxide emissions from shipping regulations reducing aerosol cooling; reduced low-level cloud amounts increasing solar radiation absorption partly due to weakened aerosol effects on clouds; solar cycle maximum increasing incoming solar energy; and temperature/water-vapour feedbacks enhancing the greenhouse effect from additional atmospheric water vapour.

The record warmth across the western North Pacific in 2025 demonstrates complex interactions beyond simple El Niño effects. This pattern aligns with the combination of La Niña conditions and a negative Pacific Decadal Oscillation phase characterizing much of the year, conditions known to favour warm SST anomalies in this basin. The high SSTs also represent continuation of marked North Pacific warming since 2013-2014, linked partly to changes in ocean mixed-layer depth.

Extreme Events and Long-Term Climate Indicators

The report documents extensive extreme events with significant impacts on human health, ecosystems, and infrastructure throughout 2025. Flash floods resulted from intense, often record precipitation in regions including the USA, China, South Korea, Pakistan, and India, plus glacier melting causing five glacial-origin floods in Nepal, Afghanistan, and Pakistan. Larger-scale flooding occurred from atmospheric rivers, monsoon rainfall, low-pressure systems, and 103 tropical storms (50 reaching tropical cyclone strength, 20 becoming major tropical cyclones) affecting populations worldwide.

Europe experienced approximately 40 named storms throughout 2025, from convective storms to major systems bringing flooding, including Storm Éowyn (January), Storm Barbara with record-breaking rainfall in Romania and Greece (October), and Storms Claudia and Emilia (November-December). Numerous heatwaves broke national or local temperature records across Asia, North America, Africa, and Europe from April to September, with some regions experiencing combinations of persistent above-average temperatures and marine heatwaves.

Heat stress analysis reveals 50% of global land areas (excluding Antarctica) experienced more days than average with at least strong heat stress (feels-like temperature of 32°C or above) in 2025. Some regions saw up to 45 more days with strong heat stress, while central Africa experienced up to 110 more days with very strong heat stress (38°C or above). Conversely, 71% of the globe saw fewer days with at least strong cold stress than average, with regions north of the Caspian Sea seeing up to 60 fewer such days.

Heatwaves, dry conditions, and strong winds fueled severe wildfires globally. According to CAMS, Europe experienced its highest annual total fire emissions in the past two decades, with the Iberian Peninsula, Scotland, eastern Mediterranean, and Balkan region severely affected. Canada recorded its second-highest annual wildfire emissions, while California saw major January wildfires following wetter-than-usual spring but exceptionally dry autumn and early winter creating abundant flammable vegetation. Russia's far east, Syria, and Australia also recorded significant wildfire activity and local emission records.

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