In one of the first of several teams of science agencies to calculate how off-the-charts warm 2023 was, the European climate agency Copernicus said the year was 1.48 degrees Celsius (2.66 degrees Fahrenheit) above pre-industrial times.
And for the first time, every day of the year was at least one degree Celsius (1.8 degrees Fahrenheit) warmer than pre-industrial times. For nearly half the year—173 days—the world was 1.5 degrees warmer than the mid-1800s.
And January 2024 is on track to be so warm that for the first time a 12-month period will exceed the 1.5-degree threshold, Copernicus Deputy Director Samantha Burgess said. Scientists have repeatedly said that Earth would need to average 1.5 degrees of warming over two or three decades to be a technical breach of the threshold.
The record heat made life miserable and sometimes deadly in Europe, North America, China and many other places last year. But scientists say a warming climate is also to blame for more extreme weather events, like the lengthy drought that devastated the Horn of Africa, the torrential downpours that wiped out dams and killed thousands in Libya and the Canada wildfires that fouled the air from North America to Europe.
“It was record-breaking for seven months. We had the warmest June, July, August, September, October, November, December,” Burgess said. “It wasn’t just a season or a month that was exceptional. It was exceptional for over half the year.”
There are several factors that made 2023 the warmest year on record, but by far the biggest factor was the ever-increasing amount of greenhouse gases in the atmosphere that trap heat, Burgess said. Those gases come from the burning of coal, oil and natural gas.
Malte Meinshausen, a University of Melbourne climate scientist, said about 1.3 degrees Celsius of the warming comes from greenhouse gases, with another 0.1 degrees Celsius from El Niño and the rest being smaller causes.
Though actual observations only date back less than two centuries, several scientists say evidence from tree rings and ice cores suggest this is the warmest the Earth has been in more than 100,000 years.
For the first time, Copernicus recorded a day where the world averaged at least 2 degrees Celsius (3.6 degrees Fahrenheit) more than pre-industrial times. It happened twice and narrowly missed a third day around Christmas, Burgess said.