The year 2023 is on track to be the hottest year ever recorded, surpassing the previous record set by 2016. The global average temperature for the first 10 months of the year was 1.43°C above the pre-industrial level, according to the World Meteorological Organization (WMO). The year has also witnessed unprecedented extreme weather events, such as heatwaves, droughts, floods, wildfires, and storms, that have caused widespread human suffering and environmental damage.
The latest data from the Copernicus Climate Change Service (C3S), the EU’s climate monitoring program, shows that October 2023 was the warmest October on record, with a global temperature anomaly of 0.85°C above the 1991-2020 average. This was 0.40°C higher than the previous warmest October in 2019. The global temperature anomaly for October 2023 was the second highest across all months in the ERA5 dataset, behind only September 2023.
The exceptional warmth in October was driven by several factors, including the ongoing influence of greenhouse gas emissions from human activities, the development of a strong El Niño event in the tropical Pacific Ocean, a reduction in sulphur pollution due to the COVID-19 pandemic, and a volcanic eruption in Tonga that injected aerosols into the stratosphere.
Some of the regions that experienced the most above-average temperatures in October were:
- Europe, where the monthly average temperature was 2.7°C above the 1991-2020 average, making it the warmest October on record for the continent. Several countries, such as Spain, France, Italy, and Greece, faced severe heatwaves, droughts, and wildfires that threatened lives and livelihoods.
- North America, where the monthly average temperature was 2.1°C above the 1991-2020 average, making it the second warmest October on record for the region. The western and central parts of the continent suffered from prolonged drought and fire conditions, while the eastern and southern parts experienced heavy rainfall and flooding.
- Asia, where the monthly average temperature was 1.4°C above the 1991-2020 average, making it the third warmest October on record for the continent. The northern and eastern parts of the continent saw unusually high temperatures and dry conditions, while the southern and western parts faced intense monsoon rains and cyclones.
- Africa, where the monthly average temperature was 1.3°C above the 1991-2020 average, making it the fourth warmest October on record for the continent. The northern and eastern parts of the continent experienced extreme heat and drought, while the central and southern parts dealt with heavy precipitation and flooding.
- Oceania, where the monthly average temperature was 0.9°C above the 1991-2020 average, making it the fifth warmest October on record for the continent. The eastern and southern parts of the continent saw above-average temperatures and dry conditions, while the western and northern parts faced below-average temperatures and wet conditions.
El Niño: A natural phenomenon with global impacts
El Niño is a natural climate phenomenon that occurs when the surface waters of the eastern and central equatorial Pacific Ocean become warmer than normal, affecting the atmospheric circulation and weather patterns around the world. El Niño typically occurs every two to seven years and lasts for several months.
According to the WMO, El Niño conditions have been developing since May 2023 and have reached a strong intensity by October 2023. The sea surface temperature anomalies in the central-eastern equatorial Pacific have risen from about 0.5°C above average in May to around 1.5°C above average in September, using the latest version of the Optimum Interpolation Sea Surface Temperature (OISST) dataset. These estimates are relative to the 1991-2020 baseline period.
The most recent expert forecasts suggest a high likelihood of continued warming in the Pacific for at least the next four overlapping three-month seasons, through to February-April 2024. A strong El Niño does not necessarily mean strong El Niño impacts locally, as other factors also influence the regional climate variability. However, some of the possible effects of El Niño on different parts of the world are:
- Drier and warmer conditions in Southeast Asia, Australia, southern Africa, and northeastern Brazil.
- Wetter and cooler conditions in the western coast of South America, Central America, the Caribbean, and parts of East Africa.
- Increased risk of tropical cyclones in the eastern and central Pacific, and decreased risk in the western Pacific and the Atlantic.
- Enhanced rainfall and flooding in the southern United States and northern Mexico, and reduced snowfall in the western United States and Canada.
- Milder and wetter winter in northern Europe, and colder and drier winter in southern Europe and the Mediterranean.
El Niño is not the only factor that drives global and regional climate patterns, and the magnitudes of El Niño indicators do not directly correspond to the magnitudes of their effects. No two El Niño events are alike, and the impacts may vary depending on the season, the location, and the interaction with other climate phenomena.
Climate change: A human-made crisis
While El Niño occurs naturally, it takes place in the context of climate change fuelled by increasing concentrations of heat-trapping greenhouse gases from human activities. Climate change has increased the frequency, intensity, and duration of heatwaves, droughts, floods, wildfires, and storms, as well as the sea level rise, ocean acidification, and biodiversity loss.
The WMO warns that the current level of global warming is already causing severe impacts on human and natural systems, and that further warming will pose even greater risks. The WMO also stresses that the world is not on track to meet the goals of the Paris Agreement, which aims to limit the global temperature rise to well below 2°C, preferably to 1.5°C, above the pre-industrial level by the end of the century.
The WMO urges the world leaders to take urgent and ambitious action to reduce greenhouse gas emissions and adapt to the inevitable impacts of climate change. The WMO also calls for enhanced cooperation and solidarity among nations, especially to support the most vulnerable and least developed countries.
The WMO’s statement comes ahead of the 28th session of the Conference of the Parties (COP28) to the United Nations Framework Convention on Climate Change (UNFCCC), which will take place in Glasgow, Scotland, from 31 October to 12 November 2023. The COP28 is expected to be a critical moment for the global response to the climate crisis, as countries are expected to submit their updated nationally determined contributions (NDCs) and long-term strategies to achieve the Paris Agreement goals.