July was the hottest month on record, at 16.95°C on average, a third of a degree more than the previous high set in summer 2019, the European Union's climate observatory Copernicus said on Tuesday.
The typical temperature was almost a full degree higher than the 1991-2020 average for July, in a month marked by wildfires and land and marine heatwaves all over the world.
Scientists previously said the record was expected.
"Heatwaves were experienced in multiple regions of the Northern Hemisphere, including southern Europe. Well-above average temperatures occurred over several South American countries and around much of Antarctica," Copernicus said.
"The month was 0.72°C warmer than the 1991-2020 average,” it said.
Beyond official records, Copernicus said proxy data for the climate going back further – such as from tree rings or ice cores – suggests the temperatures last month could be "unprecedented in our history in the last few thousand years", or possibly even longer "on the order of 100,000 years", said Carlo Buontempo, director of Copernicus.
Akshay Deoras, a research scientist at the National Centre for Atmospheric Science and the Department of Meteorology, University of Reading, told The National two factors fuelled the record breaking temperatures.
"There are two things going on. The first thing is the development of El Nino in the Pacific Ocean, which started in the month of May," he said.
"In addition to that we are seeing the clear impact of global warming. It’s not just the atmosphere or the air temperature going up. We are having problems with the sea surface temperature.
"When the sea surface temperature goes up, that impacts the atmosphere, because the atmosphere and ocean are talking to each other. So when that goes up … that changes atmospheric circulation patterns and then that influences global weather."
The presence of El Nino means hotter-than-average weather is expected from now until next summer, he said.
"What is equally likely is the odds of this happening very frequently," he added. "So that is going to go up, which means 2025 may not be that hot. But in subsequent years the chance of what we witnessed in July is going to go up."
About 1.2°C of global warming since the late 1800s, driven by the burning of fossil fuels, has made heatwaves hotter, longer and more frequent, while storms and floods have intensified.
"The global mean for 2023 is the third highest on record, at 0.43°C relative to 1991-2020, compared with 0.49°C for 2016 and 0.48°C for 2020,” said Copernicus.
“The gap between 2023 and 2016 is expected to narrow in the coming months, as the latter months of 2016 were relatively cool ... while the remainder of 2023 is expected to be relatively warm as the current El Nino event develops."
The world's oceans also smashed records, raising concerns about knock-on effects on the planet's climate, marine life and coastal communities.
The temperature of the oceans' surface rose to 20.96°C on July 30, Copernicus data showed.
The previous record was 20.95°C in March 2016, the climate observatory said.
Wildfires on the Greek island of Rhodes - in satellite pictures
The samples tested excluded polar regions.
"We just witnessed global air temperatures and global ocean surface temperatures set new all-time records in July. These records have dire consequences for both people and the planet exposed to ever more frequent and intense extreme events," said Samantha Burgess, deputy director of the Copernicus Climate Change Service.
"2023 is currently the third warmest year to date at 0.43°C above the recent average, with the average global temperature in July at 1.5°C above pre-industrial levels.
"Even if this is only temporary, it shows the urgency for ambitious efforts to reduce global greenhouse gas emissions, which are the main driver behind these records."
Forest fires have ravaged parts of Greece and burnt 12 million hectares in Canada, while southern Europe, parts of North Africa, southern United States and pockets of China have been reeling under a punishing heatwave.
Torrential rains that pummelled China's capital Beijing in recent days were the heaviest since records began 140 years ago.
Mr Buontempo earlier said the temperatures in July had been "remarkable".
UN Secretary General Antonio Guterres recently put out an SOS call.
"Climate change is here. It is terrifying. And it is just the beginning," he said, calling for immediate and bold action to cut planet-heating emissions.
"The era of global warming has ended; the era of global boiling has arrived."