In Short : Copernicus reports that 2023 stands as the hottest year on record, bringing global temperatures perilously close to the 1.5°C limit. This alarming finding emphasizes the pressing need for accelerated and comprehensive actions to address climate change and its potential ramifications.
In Detail : 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).
Global temperatures reached exceptionally high levels in 2023. The Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission with funding from the EU, monitored several key climate indicators throughout the year, reporting on record-breaking conditions such as the hottest month on record and daily global temperature averages briefly surpassing pre-industrial levels by more than 2°C. Unprecedented global temperatures from June onwards led 2023 to become the warmest year on record – overtaking by a large margin 2016, the previous warmest year. The 2023 Global Climate Highlights report 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.
Surface air temperature anomaly for 2023 relative to the average for the 1991-2020 reference period. Data source: ERA5. Credit: C3S/ECMWF.
Global surface air temperature highlights:
- 2023 is confirmed as the warmest calendar year in global temperature data records going back to 1850
- 2023 had a global average temperature of 14.98°C, 0.17°C higher than the previous highest annual value in 2016
- 2023 was 0.60°C warmer than the 1991-2020 average and 1.48°C warmer than the 1850-1900 pre-industrial level
- It is likely that a 12-month period ending in January or February 2024 will exceed 1.5°C above the pre-industrial level
- 2023 marks the first time on record that every day within a year has exceeded 1°C above the 1850-1900 pre-industrial level. Close to 50% of days were more than 1.5°C warmer then the 1850-1900 level, and two days in November were, for the first time, more than 2°C warmer.
- Annual average air temperatures were the warmest on record, or close to the warmest, over sizeable parts of all ocean basins and all continents except Australia
- Each month from June to December in 2023 was warmer than the corresponding month in any previous year
- July and August 2023 were the warmest two months on record. Boreal summer (June-August) was also the warmest season on record
- September 2023 was the month with a temperature deviation above the 1991–2020 average larger than any month in the ERA5 dataset
- December 2023 was the warmest December on record globally, with an average temperature of 13.51°C, 0.85°C above the 1991-2020 average and 1.78°C above the 1850-1900 level for the month. You can access information specific for December 2023 in our monthly bulletin
Ocean surface temperature highlights:
- Global average sea surface temperatures (SSTs) remained persistently and unusually high, reaching record levels for the time of year from April through December
- 2023 saw a transition to El Niño. In spring 2023, La Niña came to an end and El Niño conditions began to develop, with the WMO declaring the onset of El Niño in early July.
- High SSTs in most ocean basins, and in particular in the North Atlantic, played an important role in the record-breaking global SSTs
- The unprecedented SSTs were associated with marine heatwaves around the globe, including in parts of the Mediterranean, Gulf of Mexico and the Caribbean, Indian Ocean and North Pacific, and much of the North Atlantic
European temperature highlights:
- 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
- European winter (December 2022 – February 2023) was the second-warmest winter on record
- The average temperature for the European summer (June-August) was 19.63°C; at 0.83°C above average, it was the fifth-warmest on record
- European autumn (September-November) had an average temperature of 10.96°C, which is 1.43°C above average. This made autumn the second-warmest on record, just 0.03°C cooler than autumn 2020
Other remarkable highlights:
2023 was remarkable for Antarctic sea ice: it reached record low extents for the corresponding time of the year in 8 months. Both the daily and monthly extents reached all-time minima in February 2023
Arctic sea ice extent at its annual peak in March ranked amongst the four lowest for the time of the year in the satellite record. The annual minimum in September was the sixth-lowest
The atmospheric concentrations of carbon dioxide and methane continued to increase and reached record levels in 2023, reaching 419 ppm and 1902 ppb respectively. Carbon dioxide concentrations in 2023 were 2.4 ppm higher than in 2022 and methane concentrations increased by 11 ppb.
A large number of extreme events were recorded across the globe, including heatwaves, floods, droughts and wildfires. Estimated global wildfire carbon emissions in 2023 increased by 30% with respect to 2022 driven largely by persistent wildfires in Canada
Mauro Facchini, Head of Earth Observation at the Directorate General for Defence Industry and Space, European Commission, comments: “We knew thanks to the work of the Copernicus programme throughout 2023 that we would not receive good news today. But the annual data presented here provides yet more evidence of the increasing impacts of climate change. The European Union, in line with the best available science, has agreed on an emission reduction of 55% by 2030 – now just 6 years away. The challenge is clear. The Copernicus Programme, managed by the European Commission, is one the best tools available to guide our climate actions, keep us on track with the goals of the Paris Agreement and accelerate the green transition.”
Samantha Burgess, Deputy Director of the Copernicus Climate Change Service: “2023 was an exceptional year with climate records tumbling like dominoes. Not only is 2023 the warmest year on record, it is also the first year with all days over 1°C warmer than the pre-industrial period. Temperatures during 2023 likely exceed those of any period in at least the last 100,000 years.”
Carlo Buontempo, Director of the Copernicus Climate Change Service, comments: “The extremes we have observed over the last few months provide a dramatic testimony of how far we now are from the climate in which our civilisation developed. This has profound consequences for the Paris Agreement and all human endeavours. If we want to successfully manage our climate risk portfolio, we need to urgently decarbonise our economy whilst using climate data and knowledge to prepare for the future.”
Surface air temperatures broke several records globally in 2023
The earliest signs of how unusual 2023 was to become began to emerge in early June, when temperature anomalies relative to 1850-1900 pre-industrial level reached 1.5°C for several days in a row. Although this was not the first time daily anomalies had reached this level, this had never previously happened at this time of the year. For the rest of 2023, global daily temperature anomalies above 1.5°C became a regular occurrence, to the point where close to 50% of days in 2023 were in excess of 1.5°C above the 1850-1900 level.
This does not mean that we have surpassed the limits set by the Paris Agreement (as they refer to periods of at least 20 years where this average temperature anomaly is exceeded) but sets a dire precedent.
Sea Surface Temperatures (SST): beyond El Niño
A critical driver of the unusual air temperatures experienced throughout 2023 were the unprecedented high surface temperatures in the ocean. The global average SSTs(2) for the period between April and December were the highest for the time of year in the ERA5 dataset.
The main long-term factor for high ocean temperatures is the continuing increase in concentrations of greenhouse gases, but an additional contributing factor in 2023 was the El Niño Southern Oscillation (ENSO). ENSO is a pattern of natural climate variability that sees ocean temperatures in the central and eastern tropical Pacific switch between cooler (La Niña) and warmer (El Niño) than average conditions. These ENSO events influence temperature and weather patterns around the world. After La Niña concluded in early 2023 and El Niño conditions began to develop, the WMO declared the onset of El Niño in July, and conditions continued to strengthen through the rest of the year.
However, the transition to El Niño alone does not explain all of the increase in ocean surface temperatures at a global scale in 2023, as high SSTs outside of the equatorial Pacific contributed significantly to the record-breaking global SSTs.
Latitudinal contributions to the monthly global surface air temperature anomalies relative to the 1991–2020 reference period, shown separately for land and ocean regions. The contribution from each region is weighted by its area on the Earth’s surface and is highlighted with a specific colour in the bar charts. Source: ERA5. Credit: C3S/ECMWF
Marine heatwaves were a common occurrence in 2023, affecting regions such as the Mediterranean, the Gulf of Mexico and the Caribbean, the Indian Ocean and the North Pacific, and much of the North Atlantic. On longer timescales, several factors may have also influenced or reinforced the warm anomalies including heat content coming from deeper ocean levels.
Greenhouse gases
Monthly global mean atmospheric CO2 (left) and CH4 (right) column-averaged concentration from satellites for 2003-2023 (grey curve) and 12-month average (red curve). Data source: C3S/Obs4MIPs (v4.5) consolidated (2003–2022) and CAMS preliminary near real-time data (2023) GOSAT (CH4) and GOSAT-2 (CO2) records. Spatial range: 60S – 60N over land. Credit: C3S/CAMS/ECMWF/University of Bremen/SRON.
Greenhouse gas concentrations in 2023 reached the highest levels ever recorded in the atmosphere according to C3S and the Copernicus Atmosphere Monitoring Service (CAMS). Carbon dioxide concentrations in 2023 were 2.4 ppm higher than in 2022 and methane concentrations increased by 11 ppb. For 2023, the annual estimate of the atmospheric concentration of carbon dioxide is 419 ppm, and for methane the concentration is 1902 ppb. The rate of increase of carbon dioxide was similar to the rate observed in recent years. The rate of increase of methane remained high but was lower than in the last 3 years.