‘Smashed’: summer of 2023 the hottest ever recorded

The climate crisis and emerging El Niño event pushed up temperatures and drove extreme weather across the world

The summer of 2023 was the hottest ever recorded, as the climate crisis and emerging El Niño pushed up temperatures and drove extreme weather across the world.

In June, July and August – the northern hemisphere summer – the global average temperature reached 16.77C, which was 0.66C above the 1991 to 2020 average. The new high is 0.29C above the previous record set in 2019, a big jump in climate terms.

The data, from the EU’s Copernicus Climate Change Service (C3S), showed that August was about 1.5C warmer than the preindustrial average for 1850 to 1900, although the goal of the world’s nations to keep global heating below 1.5C will be considered broken only when this temperature is sustained over months and years.

Heatwaves, fires and floods have destroyed lives and livelihoods across the globe, from North and South America, to Europe, India, Japan and China.

“Our planet has just endured a season of simmering – the hottest summer on record. Climate breakdown has begun,” said the UN secretary general, António Guterres. “Scientists have long warned what our fossil fuel addiction will unleash. Our climate is imploding faster than we can cope with, with extreme weather events hitting every corner of the planet.”

The oceans have been especially hot in recent months. The C3S data showed that for every day in August, global average sea surface temperatures beat the previous record set in March 2016, which was also an El Niño year. North Atlantic Ocean temperatures reached a new record of 25.19C on 31 August. Antarctic sea ice extent has also been extremely low for the time of year.

Samantha Burgess, at C3S, said: “Global temperature records continue to tumble in 2023, with the warmest August following on from the warmest July and June, leading to the warmest boreal summer in our data record going back to 1940.” The findings are based on computer analysis of billions of measurements from satellites, ships, aircraft and weather stations around the world.

Dr Friederike Otto, at Imperial College London, said: “Breaking heat records has become the norm in 2023. Global warming continues because we have not stopped burning fossil fuels. It is that simple.

“Studies by World Weather Attribution have shown that climate change has dramatically intensified some of the most devastating weather disasters in the summer of 2023. The hot, dry and windy conditions that fuelled the wildfires in Quebec Canada were made at least twice as likely because of climate change. The extreme heatwaves that impacted Europe and North America were made 2.0-2.5C hotter because of climate change.”

The human-caused climate crisis was undeniably to blame for the deadly heatwaves that struck Europe and the US in July. Both would have been virtually impossible without the global heating driven by burning fossil fuels, scientists found.

In August, the Guardian interviewed 45 of the world’s leading climate scientists, who said that the increased heating seen in 2023 was completely in line with the predictions they had been making for decades. They said the effects were more severe than expected due to communities being more vulnerable than anticipated, making efforts to protect people more urgent than ever.

The current heatwave forecast in the UK was made five times more likely by the climate crisis, according to analysis by Climate Central. Forecasts indicate that temperatures in cities including London, Leicester, Leeds and Birmingham will be more than 10C higher than the 1991 to 2020 average for this week, the analysts said. More than 61,000 people died in the European heatwaves of 2022, according to a recent study, including more than 3,000 in the UK.

The UN’s climate change body is expected to publish a global stocktake of climate action on Friday, which it calls a “critical turning point when it comes to efforts to address climate change”.

Experts expect the findings to be “bleak”, with the world far off track to keep global heating below the Paris target of 1.5C. The world is now on track for about 2.5C of global heating, which would have devastating impacts given the increase in extreme weather already seen with just 1.2C of heating to date.

A report by leading climate scientists in March endorsed by the world’s governments, said: “There is a rapidly closing window of opportunity to secure a livable and sustainable future for all.”

Prof Mark Maslin, at University College London, said: “2023 is the year that climate records were not just broken but smashed. Extreme weather events are now common and getting worse every year – this is a wake-up call to international leaders that we must rapidly reduce carbon emissions now. Let us hope this message hits home at Cop28 in [the United Arab Emirates] this December and action actually happens.”

Guterres said: “We can still avoid the worst of climate chaos – and we don’t have a moment to lose.”

Photograph: Jeff Pachoud/AFP/Getty - Scorched sunflowers in a field during a heatwave in the village of Puy-Saint-Martin, south-east France, in August.