Average global temperatures were more than 2 degrees Celsius above a pre-industrial benchmark on Friday, preliminary data show

The planet marked an ominous milestone Friday: The first day global warmth crossed a threshold, if only briefly, that climate scientists have warned could have calamitous consequences.

Preliminary data show global temperatures averaged more than 2 degrees Celsius (3.6 degrees Fahrenheit) above a historic norm, from a time before humans started consuming fossil fuels and emitting planet-warming greenhouse gases.

That does not mean efforts to limit global warming have failed — yet. Temperatures would have to surpass the 2-degree benchmark for months and years at a time before scientists consider it breached.

But it’s a striking reminder that the climate is moving into uncharted territory. Friday marked the first time that everyday fluctuations around global temperature norms, which have been steadily increasing for decades, swung the planet beyond the dangerous threshold. It occurs after months of record warmth that have stunned many scientists, defying some expectations of how quickly temperatures would accelerate this year.

“I think while we should not read too much into a single day above 2C (or 1.5C for that matter) it’s a startling sign nonetheless of the level of extreme global temperatures we are experiencing in 2023,” Zeke Hausfather, a climate scientist with Stripe and Berkeley Earth, said in a message to The Washington Post.

Samantha Burgess, deputy director of the European Union’s Copernicus Climate Change Service, said Sunday on the social media platform X that Friday’s global temperatures were 1.17C (2.1F) above the 1991-2020 average, a record-setting margin.

Given how much human-caused warming had occurred by that period, that means Friday’s average global temperature was 2.06C (3.7F) above a preindustrial reference period, 1850-1900, she said.

Provisional ERA5 global temperature for 17th November from @CopernicusECMWF was 1.17°C above 1991-2020 - the warmest on record.

Our best estimate is that this was the first day when global temperature was more than 2°C above 1850-1900 (or pre-industrial) levels, at 2.06°C. pic.twitter.com/jXF8oRZeip

— Dr Sam Burgess 🌍🌡🛰 (@OceanTerra) November 19, 2023

The estimate of global warmth comes from a European model that uses the same sorts of observations used in weather predictions to instead look backward, and estimate global climate conditions nearly in real time.

Direct observations that scientists will gather and vet in the coming weeks could soon confirm the record warmth.

A year of record-setting warmth continues

That the globe surpassed the 2-degree warming benchmark for at least one day adds an exclamation point to a string of temperature records set in recent months.

Global temperatures set records in July, August, September and October. The Copernicus data shows that trend has been maintained, if not accelerated, into November.

Even before Saturday, scientists said 2023 was virtually certain to surpass 2016 as the globe’s warmest on record, and likely to mark one of its warmest periods in 125,000 years, going back to a time before Earth’s last ice age. That estimate is based on paleoclimate records that show there was at least no extended period of the sort of warmth the planet is now experiencing, and that temperatures are rising with unprecedented speed.

Analyses released this month show 2023 average global temperatures are likely to end up 1.3 to 1.4C (2.3 to 2.5F) above preindustrial levels. Climate scientists predict that sustained global warming at 1.5 degrees above preindustrial levels could overwhelm societies and upend economies and political systems.

Planetary warming is only expected to accelerate in the coming months because of a deepening El Niño, the infamous climate pattern that drives weather extremes and raises global temperatures by releasing vast stores of heat from the Pacific Ocean into the atmosphere.

But that surge of El Niño-fueled warmth typically does not arrive until after the climate pattern reaches its peak — something forecast to occur this winter. Because of that, scientists had said earlier this year they did not expect the globe to surge to such record warmth until 2024.

Friday’s milestone offers yet more proof of how the planet has defied climate scientists’ expectations this year.