The past week was the hottest ever recorded on Earth

Global temperatures once again hit a new record high on 6 July, with average global air temperature recorded 2 metres above Earth’s surface reaching 17.23°C (63.01°F), according to preliminary data from the National Oceanic and Atmospheric Administration compiled by the University of Maine’s Climate Reanalyzer.

That surpassed the joint record set on 4 and 5 July of 17.18°C (62.92°F), which itself had smashed the record set on 3 July of 17.01°C (62.62°F). The past seven days have been the hottest on Earth since instrumental records began in the 1850s. Karsten Haustein at the University of Leipzig, Germany, says the last time Earth was this warm was in the Eemian interglacial period, around 120,000 years ago.

“The situation we are witnessing now is the demonstration that climate change is out of control,” UN secretary-general António Guterres said earlier this week, in a statement. “If we persist in delaying key measures that are needed, I think we are moving into a catastrophic situation, as the last two records in temperature demonstrates.”

The records were partly confirmed by data from the European Union’s climate monitoring service Copernicus, which said its ERA5 dataset had also recorded record high global surface air temperatures on 3 and 4 July. It told New Scientist that preliminary data suggests 5 July was also a day of record warmth.

Previous to this week, 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), according to Climate Reanalyzer.

Scientists said the high global temperatures are being driven by a combination of climate change and an unusually wavy band of strong winds, known as the jet stream, high over the North Atlantic.

Piers Forster at the University of Leeds, UK, says the searing heat experienced across Canada, the US and Mexico in the past few weeks – where temperatures have soared above 46°C (115°F) in some places – is partly to blame.

The persistent heatwave has been caused by an “omega” pattern in the jet stream, which is holding the hot weather in place and helping to drive record-high global air temperatures. This “wavy” jet stream pattern may be a secondary effect of climate change, says Forster, which could mean that such runs of record-breaking air temperatures could become more common in the future.

“It’s very peculiar,” he says. “We are certainly observing the impacts of climate change increasing the Earth’s surface temperature – that is absolutely occurring and part of what’s going on. But there could potentially also be the effect of secondary climate change on the circulation as well, and that is potentially quite worrisome because that would suggest we could get into these long periods of extreme heat more often.”

An accelerating El Niño climate pattern, where higher temperatures in the Pacific Ocean drive warmer, more extreme weather across the world, could mean more record-breaking weather to come later this year, says Robert Rohde at Berkeley Earth in California. This year is “more likely than not” to be the hottest on record, he says.

Warmer than usual winter temperatures in Antarctica, which have driven record low levels of sea ice this year, will also have tweaked global average temperatures higher than normal, Haustein says. That factor, coupled with the arrival of El Niño and ongoing human-caused climate change, means it is “quite obvious that you should expect a new record,” he says. “It is, in fact, unavoidable.”

Following the end of El Niño, likely to be in around two years’ time, global average temperatures will dip back towards normal levels, says Forster. But climate change means there will be a “continually warming baseline” to contend with. Cutting greenhouse gas emissions as far and fast as possible is the best route to minimising the occurrence of record-breaking heat in the future, he says.

“We can really change in a positive way how much temperature increase there is over the next two decades,” he says. “It can either get a little bit worse than now or an awful lot worse than now.”