Copernicus Climate Change Service (C3S) puts the chance that 2026 will average above 1.5°C over the 1850–1900 level at more than 99%, though one year does not define the Paris Agreement’s long-term goal.
C3S estimates the annual temperature anomaly will fall between 1.56°C and 1.61°C. Its model gives the year an 80% chance of finishing second warmest and a 20% chance of matching or exceeding 2024, currently the warmest year in the ERA5 record.
The estimate uses readings through October and a statistical method calibrated against ERA5 observations from 1979 through 2025. C3S says the odds may differ with another dataset, modeling approach or historical period. The service also projects that the average for 2023–2026 will exceed 1.5°C.
ERA5’s global mean surface-air temperature reached 15.35°C in October, 1.75°C above the estimated 1850–1900 average. It was the record’s warmest October and the third month in a row above 1.5°C.
Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts, said an exceptionally strong El Niño is adding warmth alongside the human-caused warming already present.
The World Meteorological Organization says the Paris Agreement’s temperature benchmarks concern long-term warming, generally assessed across 20 years. The 2026 projection alone therefore does not establish that the agreement’s 1.5°C goal has been exceeded.
The United Nations Environment Programme says a modeled pathway with about a 50% chance of returning warming to 1.5°C or lower by 2100 would require global emissions to fall 18% by 2030, 45% by 2035 and 69% by 2040, measured against 2025 levels. Those reductions are part of UNEP’s modeled emissions pathway.
