Multiple relentless heatwaves occurred in 2023, with much of the world experiencing at least 20 more heatwave days than the 1991–2020 average. Prominent and record-breaking events included exceptional wintertime and spring heat in South America, large heatwaves over Europe, Africa and Asia, and a prolonged event over south-eastern USA and Central America.

Key points

Persistent heatwaves across much of the globe were synonymous with the hottest year on record.
Many 2023 heatwaves exhibited record-smashing extreme temperatures, including a widespread heatwave spanning Thailand to Northern China that featured the worst April heatwave in South China on record.
South America saw many prominent heat events, with exceptional heat in winter and early spring that broke all-time summertime records.

2023 was the hottest year on record. The global average temperature was 1.45 °C above pre-industrial (1850–1900) values, beating the previous record, which was set in 2016, by 0.16 °C. Behind this remarkable anomaly were many global temperature records, including: the hottest month and season ever recorded (July and June–August; both approaching 17 °C, which is 0.72 °C and 0.66 °C above average, respectively); daily instances of global temperatures 2 °C above pre-industrial levels; and 23% of land regions setting new extreme heat records. However, these figures hide the plethora of extraordinary daily and regional-scale terrestrial heat extremes, each linked to a combination of large- and local-scale drivers and feedbacks, such as anthropogenic climate change, persistent atmospheric blocking, droughts, adjacent marine heatwaves and the developing El Niño.

Here, we summarize extreme terrestrial heat events during 2023 using ERA5 reanalysis. Not all events — of which there are many — are discussed, and Australia is omitted, since record-breaking heat extremes over this continent were minimal. Throughout, anomalies are calculated with respect to 1991–2020.

Heatwave activity in 2023

Climate impacts and risks

Publications

Dubai 17/4/24. Areas of flooding in turquoise. Source: Copernicus Sentinel-2 (CC BY-SA 3.0 IGO)

Heavy precipitation hitting vulnerable communities in the UAE and Oman becoming an increasing threat as the climate warms

Researchers have assessed the extent human-induced climate change altered the likelihood and intensity of the weather conditions that caused the flooding in the United Arab Emirates and the northern parts of Oman in April 14–15 2024. The region was hit by exceptionally heavy rainfall causing massive disruption in infrastructure and public life in the area and leading to at least 20 fatalities in Oman and four in the UAE.

The impacts of multiple tropical cyclone events and associated precipitation on household income and expenditures

Climate change-fueled tropical cyclones have already reduced household incomes across the Philippines by 7% on average, according to a new study. This figure rises to more than 20% in some provinces.

Mapping the climate risk to urban forests at city scale

This study uses an urban tree inventory and high-resolution climate projections to identify species and locations at risk from climate change in Melbourne. It finds that half of the tree species in Melbourne are at risk from heat stress, which could climb to two thirds in 2050.

The 1.5°C limit and risks of overshoot

This briefing looks at what the 1.5°C limit means in terms of adaptation and loss and damage for the most vulnerable countries and regions. It finds that slowing down warming is critical to buy us time to adapt and also to avoid irreversible loss and damage. Even if warming rises above 1.5°C (overshoot) we can bring it down again with ambitious emissions reductions.

Hydrologic interpretation of machine learning models for 10-daily streamflow simulation in climate sensitive upper Indus catchments

This study augments physical hydrological modeling with machine learning models to simulate surface water flows in Upper Indus water catchments in Pakistan.

Le seuil de +1,5°C et le risque de dépassement de ce seuil

Ce rapport examine ce que la limite de 1,5 °C signifie en termes d'adaptation et de pertes et dommages pour les pays et régions les plus vulnérables. Il constate qu'il est essentiel de ralentir le réchauffement pour nous donner le temps de nous adapter et pour éviter des pertes et des dommages irréversibles. Même si le réchauffement dépasse 1,5 °C, nous pouvons le faire baisser à nouveau en réduisant les émissions de manière ambitieuse.

Representing natural climate variability in an event attribution context: Indo-Pakistani heatwave of 2022

New study finds that the 2022 Indo-Pakistani heatwave was both more likely to occur and more intense due to increasing global warming – even when accounting for the effects of natural climate variability and the forced response to anthropogenic climate change.

Climate impacts in northern forests

Northern forests hold around 54% of the world’s total terrestrial carbon stock and contribute more than one-third to our global terrestrial carbon sink. This report reviews the impact of human induced climate change on northern temperate and boreal forests.

Effects of idealised land cover and land management changes on the atmospheric water cycle

This study investigates how land cover and land management affects atmospheric moisture transport using global climate models. It finds that cropland expansion is generally causing a drying and reduced local moisture recycling, while afforestation and irrigation expansion generally cause wetting and increased local moisture recycling.

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A better integration of health and economic impact assessments of climate change

This study lays out how to integrate the economic repercussions of climate change on people's health with direct health impacts. The authors argue this could provide more realistic scenario projections than health studies on their own and be more useful for adaptation policy.

Kipppunkte und kaskadische Kippdynamiken im Klimasystem

Dieser im Auftrag des deutschen Umweltbundesamtes erstellte Bericht befasst sich mit Kippelementen - sensible Komponenten des Erdsystems, die bei Überschreiten kritischer Schwellenwerte (Kipppunkte) irreversiblen Veränderungen ausgesetzt werden können. Er unterstreicht, dass selbstverstärkende Mechanismen zwischen diesen Elementen zu schnellen, irreversiblen Veränderungen führen können.

Hitzestress und Anpassungsmaßnahmen in der Metropolregion Berlin-Brandenburg

Städte sind dabei besonders anfällig für Hitzestress. Deshalb betrachten wir in diesem Bericht die Folgen des Klimawandels auf die Metropolregion Berlin-Brandenburg, mit einem speziellen Fokus auf die Auswirkungen von Hitzestress und die Entwicklung von Anpassungsstrategien.

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Extreme terrestrial heat in 2023