Excerpt from the surface air temperature anomaly image for 2023 shown below. Data source: ERA5. Credit: C3S/ECMWF.
High temperatures from June onwards led to 2023 becoming the warmest year on record by a large margin, close to 1.5°C above the pre-industrial level, according to the EU’s Copernicus Climate Change Service (C3S) implemented by ECMWF.
The year also saw the hottest month on record, and daily global temperatures briefly surpassed pre-industrial levels by more than 2°C.
The 2023 Global Climate Highlights report, which is based mainly on the ERA5 reanalysis dataset, presents a general summary of 2023's most relevant climate extremes and the main drivers behind them, such as greenhouse gas concentrations, El Niño and other natural variations.
Hottest year
2023 was the warmest calendar year in global temperature data records going back to 1850. The global average temperature was 14.98°C. That is 0.17°C higher than the previous highest annual value, reached in 2016.
Global temperatures in 2023 were 1.48°C warmer than the 1850–1900 pre-industrial level. That means they were close to the preferred 1.5°C limit of the Paris Climate Accords.
Global surface air temperature increase relative to the average for 1850–1900, the designated pre-industrial reference period based on several global temperature datasets shown as 5-year averages since 1850 (left) and as annual averages since 1967 (right). Credit: C3S/ECMWF.
July and August 2023 were the warmest two months on record, and two days in November were, for the first time, more than 2°C warmer than the 1850–1900 level.
Each month from June to December in 2023 was warmer than the corresponding month in any previous year.
Surface air temperature anomaly for 2023 relative to the average for the 1991–2020 reference period. Data source: ERA5. Credit: C3S/ECMWF.
Ocean surface temperatures
Global average sea-surface temperatures (SSTs) remained persistently and unusually high, reaching record levels for the time of year from April to December.
2023 saw a transition to the warm phase of the El Niño–Southern Oscillation (ENSO), called El Niño. ENSO is a variation in winds and sea-surface temperatures over the tropical eastern Pacific Ocean. It affects the climate of much of the tropics and subtropics.
But high SSTs in most ocean basins, and in particular in the North Atlantic, played an important role in the record-breaking global SSTs.
European temperatures
2023 was the second-warmest year for Europe, at 1.02°C above the 1991–2020 average, 0.17°C cooler than 2020, the warmest year on record.
Temperatures in Europe were above average for 11 months during 2023, and September was the warmest September on record.
More information
More details can be found in the the Global Climate Highlights report on the C3S website.
A recording of the press event is available on YouTube.