We have just experienced the hottest day ever recorded on Earth – for the second day in a row. The average global air temperature recorded 2 metres above Earth’s surface hit 17.18°C (62.92°F) on 4 July, according to data from the National Oceanic Atmospheric Administration (NOAA) and compiled by the University of Maine.
The new record outstrips the previous high of 17.01°C (62.62°F) set on 3 July. It makes 4 July the hottest day ever on Earth since records began.
Before that, the next highest-temperature on record was recorded jointly in August 2016 and July 2022, when average global temperatures reached 16.92°C (62.46°F).
The two consecutive days of record-breaking global heat confirms scientists’ warnings that 2023 is likely to be one of the hottest years on record, as the twin effects of climate change and a warming El Nino climate pattern drive temperatures to new highs.
Robert Rohde at Berkeley Earth in California says warming in the Pacific Ocean, which heralds the start of an El Nino event, is a key driver of the high global temperatures.
“The El Niño event was officially declared by NOAA right at the start of June,” he says. “The warming has been expanding in the Pacific and that is likely to be contributing to things [temperatures] inching up a bit higher in July than in previous months.”
Recent heatwaves across the US, Europe and Canada will also have played a role, he says.
This specific NOAA/Maine data set only goes back to 1979, but it is comparable with other data that goes back much further. Rohde says he is confident that it is the highest ever since instrumental measurements began, around the 1850s. It is an “expected milestone”, he says, given the twin drivers of climate change and extra warming from El Niño.
“We will keep passing these thresholds every few years if we have El Niño variability on top of global warming, until we get global warming under control,” says Rohde.
Meanwhile, data from the EU’s Copernicus Climate Change Service this week confirmed that global average temperatures in June 2023 were 1.46°C above pre-industrial levels, edging ever closer to the 1.5°C threshold countries have vowed not to exceed.
Global average air temperatures follow the seasonal cycles of the northern hemisphere, with temperatures peaking in July. That is because air temperatures fluctuate more over land than over water, and as the northern hemisphere boasts more land mass than the southern hemisphere, it has a larger influence over the global average.
With El Niño continuing to build through the rest of the year and high summer arriving in the northern hemisphere, Rohde believes it is likely that July and August will also see high – even record – average global temperatures. This year is “more likely than not” to be the hottest year on record, he says.
