Data for August 2023 shows that the month set a new all-time heat record with an average temperature of 16.82°C – 0.71°C warmer than the 1991-2020 average, and more alarmingly, 1.5°C above the pre-industrial average of 1850-1900, a key threshold beyond which experts say the planet will be pushed into irrevocable climate changes.

The hottest August came right on the heels of the hottest July — about 0.33° warmer than the previous warmest month, July 2019 — and the hottest June, which was 0.13°C warmer than the previous record set by June 2020.

Seen together, the three months made the 2023 summer surpass the 2019 record of 16.48°C by a wide margin, C3S said in a statement.

The new data prompted yet another stark warning from the UN secretary-general Antonio Guterres, who said that “climate breakdown has begun”.

“Our planet has just endured a season of simmering — the hottest summer on record… Scientists have long warned what our fossil fuel addiction will unleash,” Guterres said in a statement. He also repeated his call for action from world leaders. “Surging temperatures demand a surge in action. Leaders must turn up the heat now for climate solutions. We can still avoid the worst of climate chaos — and we don’t have a moment to lose,” he said.

While the eight months of the year so far have been the second warmest in history – only 0.01°C below the all-time high of 2016 – August alone is estimated to have been around 1.5°C warmer than the pre-industrial average for 1850-1900. To be sure, this monthly blip is not the same as breaching the Paris Agreement threshold (which requires nations to limit temperature rise to 1.5°C): That will only be considered broken when this temperature is sustained over months and years.

Scientists said 2023 will likely end up the warmest ever.

“Looking at the additional heat we have in the ocean surface, the probability is that 2023 will end up being the warmest year on record,” Samantha Burgess, deputy director of the Copernicus Climate Change Service, told AFP.

If the Northern Hemisphere has a “normal” winter, “we can almost virtually say that 2023 will be the warmest year that humanity has experienced,” Burgess said.

Scientists have blamed human-induced global warming with an extra push from an El Nino, a warming of the Pacific Ocean that impacts the weather worldwide. WMO, on July 4, said that an El Nino had set in, “setting the stage for a likely surge in global temperatures and disruptive weather and climate patterns”.

To make matters worse, next year is slated to be warmer. “It is worth noting that this is happening before we see the full warming impact of the El Nino event, which typically plays out in the second year after it develops,” WMO’s secretary-general, Petteri Taalas, said in a statement on Wednesday. A strong El Nino coincided with the all-time high temperatures in 2016.

The Northern Hemisphere, including southern Europe, the southern US, and Japan have experienced heatwaves over the last few months, while regions in Australia, South America, and Antarctica have recorded temperatures well-above average.

Closer home, the impact was felt in the excruciating summer in June and July, and the havoc that monsoon rains have unleashed in the Himalayan states. On September 4, Delhi recorded its hottest September day since 1938, with a maximum temperature of 40.1°C.

“What we are observing is not only new extremes but the persistence of these record-breaking conditions, and the impacts these have on both people and planet, are a clear consequence of the warming of the climate system,” Carlo Buontempo, director of the Copernicus Climate Change Service, ECMWF, said in a statement.

Temperatures in the oceans — more than 70% of the Earth’s surface — have also entered uncharted territory, with the North Atlantic Ocean reaching a new high of 25.19°C on August 31, according to C3S data. Oceans have absorbed 90% of the excess heat produced by human activity since the dawn of the industrial age.

Antarctic sea ice extent remained at a record low level for the time of year, with a monthly value 12% below average. This figure is more alarming since the region is in the dead of winter, when sea ice seasonally builds back up.

The UN weather agency, in May this year, rolled out predictions that suggest Earth would within the next five years have a year that averages 1.5°Celsius warmer than in the mid-19th century.

It also predicted a 98% chance of breaking the 2016 record between now and 2027.

Usually an El Nino, which started earlier this year, adds extra heat to global temperatures but more so in its second year.

With the release of the new data on Wednesday, Burgess said, “The scientific evidence is overwhelming, we will continue to see more climate records and more intense and frequent extreme weather events impacting society and ecosystems, until we stop emitting greenhouse gases.”