A billboard displays a temperature of 48 degrees Celcius (118 degrees Fahrenheit) during a record heat wave in Phoenix, Arizona. File /AFP

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 above pre-industrial times.

That's barely below the 1.5 degrees Celsius limit that the world hoped to stay within in the 2015 Paris climate accord to avoid the most severe effects of warming.

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 1.5 degree goal "has to be (kept) alive because lives are at risk and choices have to be made,” Burgess said. "And these choices don’t impact you and I but they impact our children and our grandchildren.”

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.

For the first time, nations meeting for annual United Nations climate talks in December agreed that the world needs to transition away from the fossil fuels that are causing climate change, but they set no concrete requirements to do so.

Copernicus calculated that the global average temperature for 2023 was about one-sixth of a degree Celsius warmer than the old record set in 2016.

While that seems a small amount in global record-keeping, it's an exceptionally large margin for the new record, Burgess said. Earth's average temperature for 2023 was 14.98 degrees Celsius (58.96 degrees Fahrenheit), Copernicus calculated.

"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.

Other factors including the natural El Nino - a temporary warming of the central Pacific that alters weather worldwide - other natural oscillations in the Arctic, southern and Indian oceans, increased solar activity and the 2022 eruption of an undersea volcano that sent water vapor into the atmosphere, Burgess said.

Associated Press