3 years since 2023 have been the hottest as also the period from 2015-2025, says WMO
The three years from 2023 and the period from 2015 to 2025 have been the hottest ones on record, the World Meteorological Organisation (WMO) said on Thursday.
In its State of the Global Climate Update 2025 report, it said 2025 will likely be the second or third-hottest year on record. Global temperatures so far in 2025 are around 1.4°C above the pre-industrial average.
Heat and Ice
The report said oceans are absorbing more heat. Sea ice in the Arctic after the winter freeze was the lowest-ever recorded and Antarctic sea ice remained well below average throughout the year. Sea levels are still rising, even though there was a short dip briefly, influenced by La Niña and other factors. These changes are linked to stronger heatwaves, flooding and wildfire risks across regions, affecting lives, livelihoods and food systems.
Temperature sequence
The mean near-surface temperature from January to August 2025 was 1.42°C ± 0.12°C above the pre-industrial average, according to the report. The 26-month period from June 2023 to August 2025 recorded an unbroken run of monthly temperature records, except for February 2025.
Warming El Niño conditions that pushed global temperatures up during 2023 and 2024 shifted to neutral/La Niña conditions in 2025. While this made 2025 slightly cooler than 2024, temperatures remain exceptionally high. The report said the high temperatures of the past three years compared with the previous two are linked to the end of a prolonged La Niña that lasted from 2020 to early 2023.
Increasing sea level
Preliminary data show that ocean heat content has been increasing in 2025, exceeding the record levels of 2024. Over 90 per cent of excess heat trapped by greenhouse gases is absorbed by the ocean, which warms waters, reduces the ocean’s role as a carbon sink, and contributes to sea-level rise.
The long-term rate of sea-level rise has accelerated, nearly doubling from 2.1 mm per year between 1993 and 2002 to around 4.1 mm per year between 2016 and 2025, driven by warming oceans, thermal expansion and melting glaciers.
The year 2024 reached a new record high for annual global mean sea level. Preliminary 2025 data show a small decline, which the report notes as temporary, influenced by La Niña.
Glacier Loss
The hydrological year 2023/2024 was the third consecutive year where glaciated regions recorded net mass loss. Reference glaciers monitored by the World Glacier Monitoring Service show a global annual mass balance of −1.3 m water equivalent or around 450 gigatonnes of ice lost, contributing about 1.2 mm of global sea-level rise. This is considered as the largest recorded loss of ice since 1950.
Greenhouse Gas Levels
Concentrations of carbon dioxide, methane, and nitrous oxide reached record highs in 2024 and early measurements indicate they will be even higher in 2025.
CO₂ has risen from 278 ppm in 1750 to 423.9 ppm in 2024, a 53 per cent increase, with 2023–2024 showing a record annual rise of 3.5 ppm, says the report.
Urgent Warnings
WMO Secretary-General Celeste Saulo said the continued rise in temperatures and last year’s record-high greenhouse gas increase make it extremely difficult to limit warming to 1.5°C in the next few years without briefly exceeding it, though it remains possible and essential to bring temperatures back down by the end of the century.
UN Secretary-General António Guterres, citing the report at the Belém Climate Summit (COP30), said each year above 1.5°C will strain economies, widen inequalities, and cause lasting damage, calling for faster and broader climate action.
Early Warnings
The WMO report emphasised the need for focused efforts worldwide to enhance forecasting and risk preparedness. Since 2015, countries using multi-hazard early warning systems (MHEWS) have grown from 56 to 119 as of 2024, more than doubling in under a decade. Yet about 40 per cent of countries still do not have these systems. The report also points out that as renewable energy capacity continues to grow, climate information will be crucial for planning reliable and flexible power systems.
Published on November 6, 2025
