September 2023 was world’s hottest September on record by ‘extraordinary’ margin, new data confirms, with scientists blaming more than climate change
September 2023 was not only the hottest September on record, new data has confirmed today, but it was warmer by a margin described by stunned scientists as “extraordinary”, “huge” and “whopping”.
It keeps the world on course for its hottest year ever, expected to be 1.4C warmer than before the industrial era.
The new record is just the latest to be shattered this year, following a record hot June, July and summer overall, and record hot September in the UK.
Scientists are pointing the finger primarily at climate change, and warned of worse to come. But they also put it down to a warm weather pattern called El Nino, and natural changes in the weather.
The Copernicus Climate Change Service (C3S) confirmed today that in September average surface air temperatures globally reached 16.38C.
The figure is 0.93C above the average for September during the last two decades, and a significant 0.5C warmer than the previous warmest ever September, in 2020.
The margin has astonished scientists.
Record heat in September smashed previous records by a “huge” 0.5C margin
“It’s huge,” said Professor Ed Hawkins, climate scientist at Reading University. “We shouldn’t be breaking records by this amount.”
Piers Forster – the interim chair of the government’s Climate Change Committee but speaking in his capacity as climate change professor at Leeds University – said variations between months each year are usually quite small.
“Therefore, breaking the previous September record by a whopping 0.5C is crazy and shows something really bizarre is going on,” he said.
Dr Samantha Burgess, deputy director of C3S, said the “unprecedented temperatures” for September broke records by “an extraordinary amount”.
With two months until the next global climate talks, COP28 in Dubai in December, the “urgency for ambitious climate action has never been more critical”, added Dr Burgess.
The sea was hot too
Today’s findings are based on billions of measurements from satellites, ships, aircraft and weather stations around the world.
They confirmed that temperatures on the ocean surface had also soared in September, reaching the second highest ever, behind only August 2023.
Scientists have also been alarmed by the record low sea ice cover in Antarctica, which C3S confirmed has continued into September.
It is fuelling worries that climate change is finally catching up with the continent once thought to be relatively shielded.
Source: National Snow and Ice Data Center
Why was September and this summer so hot globally?
Part of the heat has come from a natural switch in the tropical east Pacific around July from a cool El Nina phase to a warm El Nino one, influencing temperatures around the world.
But while a combination of factors are at play, including natural variability from year to year, scientists believe the main cause is climate change.
Prof Forster said: “We think it’s caused by a combination of factors, principally greenhouse gas emissions being at an all time high.”
Global temperatures have warmed by around 1.1C since the pre-industrial era due to human activity, according to UN’s Intergovernmental Panel on Climate Change.
“What we’re seeing this year is there is a bump on top of that,” said Prof Hawkins, which could be “due to other factors such as El Nino or other weather patterns”.
“But the largest component by far is the fact that we have added so much greenhouse gases in the atmosphere from burning fossil fuels.”
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UK climate deaths since 1990
Prof Hawkins said month after month of record heat was not necessarily a sign the climate crisis was accelerating, but a taste of the future under continued global warming.
Extreme weather events this summer – like fires in the Mediterranean, floods in New York or heatwaves in the UK – will become “more frequent and sadly become normal”, he added.
He said climate change is exacerbating flooding because warmer air can hold more water, meaning rainfall is heavier.
It also makes naturally occurring heatwaves even hotter, and it fuels the hot and dry conditions that allow wildfires to spread rapidly, even if the fires were sparked by something unrelated, he added.
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World
Stock markets slump for second day running after Trump announces tariffs – in worst day for indexes since COVID
Worldwide stock markets have plummeted for the second day running as the fallout from Donald Trump’s global tariffs continues.
While European and Asian markets suffered notable falls, American indexes were the worst hit, with Wall Street closing to a sea of red on Friday following Thursday’s rout – the worst day in US markets since the COVID-19 pandemic.
As it happened: Worst week’s trading in five years
All three of the US’s major indexes were down by more than 5% at market close; The Dow Jones Industrial Average plummeted 5.5%, the S&P 500 was 5.97% lower, and the Nasdaq Composite slipped 5.82%.
The Nasdaq was also 22% below its record-high set in December, which indicates a bear market.
Read more: What’s a bear market?
Ever since the US president announced the tariffs on Wednesday evening, analysts estimate that around $4.9trn (£3.8trn) has been wiped off the value of the global stock market.
Mr Trump has remained unapologetic as the markets struggle, posting in all-caps on Truth Social before the markets closed that “only the weak will fail”.
The UK’s leading stock market, the FTSE 100, also suffered its worst daily drop in more than five years, closing 4.95% down, a level not seen since March 2020.
And the Japanese exchange Nikkei 225 dropped by 2.75% at end of trading, down 20% from its recent peak in July last year.
US indexes had the worst day of trading since the COVID-19 pandemic. Pic: Reuters
Trump holds trade deal talks – reports
It comes as a source told CNN that Mr Trump has been in discussions with Vietnamese, Indian and Israeli representatives to negotiate bespoke trade deals that could alleviate proposed tariffs on those countries before a deadline next week.
The source told the US broadcaster the talks were being held in advance of the reciprocal levies going into effect next week.
Vietnam faced one of the highest reciprocal tariffs announced by the US president this week, with 46% rates on imports. Israeli imports face a 17% rate, and Indian goods will be subject to 26% tariffs.
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Do Trump’s tariffs add up?
Read more:
Markets gave Trump a clear no-confidence vote
There were no winners from Trump’s tariff gameshow
China – hit with 34% tariffs on imported goods – has also announced it will issue its own levy of the same rate on US imports.
Mr Trump said China “played it wrong” and “panicked – the one thing they cannot afford to do” in another all-caps Truth Social post earlier on Friday.
Later, on Air Force One, the US president told reporters that “the beauty” of the tariffs is that they allow for negotiations, referencing talks with Chinese company ByteDance on the sale of social media app TikTok.
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Tariffs: Xi hits back at Trump
He said: “We have a situation with TikTok where China will probably say, ‘We’ll approve a deal, but will you do something on the tariffs?’
“The tariffs give us great power to negotiate. They always have.”
World
Financial markets were always going to respond to Trump tariffs but they’re also battling with another problem
South Korea’s constitutional court has confirmed the dismissal of President Yoon Suk Yeol, who was impeached in December after declaring martial law.
His decision to send troops onto the streets led to the country’s worst political crisis in decades.
The court ruled to uphold the impeachment saying the conservative leader “violated his duty as commander-in-chief by mobilising troops” when he declared martial law.
The president was also said to have taken actions “beyond the powers provided in the constitution”.
Demonstrators stayed overnight near the constitutional court. Pic: AP
Supporters and opponents of the president gathered in their thousands in central Seoul as they awaited the ruling.
The 64-year-old shocked MPs, the public and international allies in early December when he declared martial law, meaning all existing laws regarding civilians were suspended in place of military law.
Read more from Sky News:
Highs and lows of Five-Year Keir
MP tells Sky News she was targeted online by Tate brothers
The court was under heavy police security guard ahead of the announcement. Pic: AP
After suddenly declaring martial law, Mr Yoon sent hundreds of soldiers and police officers to the National Assembly.
He has argued that he sought to maintain order, but some senior military and police officers sent there have told hearings and investigators that Mr Yoon ordered them to drag out politicians to prevent an assembly vote on his decree.
His presidential powers were suspended when the opposition-dominated assembly voted to impeach him on 14 December, accusing him of rebellion.
The unanimous verdict to uphold parliament’s impeachment and remove Mr Yoon from office required the support of at least six of the court’s eight justices.
South Korea must hold a national election within two months to find a new leader.
Lee Jae-myung, leader of the main liberal opposition Democratic Party, is the early favourite to become the country’s next president, according to surveys.
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