We have arrived at the place where climate scientists say we shouldn’t be.

For the first time, the world’s average annual temperature has exceeded 1.5 degrees Celsius above preindustrial levels during a calendar year.

A report released Thursday by Europe’s Copernicus Climate Change Service show that not only was 2024 the hottest year ever measured – easily beating a record set just 12 months earlier – but it marks the planet’s entry into a heat regime that the Paris climate agreement explicitly aims to avoid.

People need scarcely look for signs that rising temperatures are having their predicted effect. Fires raging in the suburbs of Los Angeles this week are just the latest example of a series of extreme weather events that have racked up damage and death around the globe.

“These high global temperatures, coupled with record global atmospheric water vapour levels in 2024, meant unprecedented heatwaves and heavy rainfall events, causing misery for millions of people,” Samantha Burgess, the service’s deputy director, said in a statement accompanying the release.

If there is a caveat, it is that the global figure represents a combination of factors. Climate change spurred by fossil-fuel use is the primary driver of the warming. But the first part of last year was also affected by the tail end of the previous year’s El Nino, a Pacific Ocean phenomenon that can raise temperatures globally.

The European organization also updated its running five-year average, which offers a more smoothed-out view of what the global temperature is doing. This puts the planet at about 1.3 degrees warmer than it was between 1850 and 1900. But it still shows 2024 as the warmest year yet. And there is little doubt about where things are heading.

“It’s basically a clear signal that we’ve arrived or we’re very close to arriving at the threshold we were trying to stay under,” said Frédéric Fabry, a meteorologist and professor at McGill University in Montreal. “In a few years we will hit that 1.5-degree warming regularly.”

While such shifts may seem modest when expressed as a global average, they disguise the increasing frequency with which extreme weather is affecting life around the world.

“Exceptional events that we’re not equipped to deal with because they are so rare are becoming more common – and we’re starting to see it,” Dr. Fabry said.

A list of extreme weather events Canada has seen over the past 12 months includes serious flooding in Toronto and Montreal, a record-breaking hailstorm in Calgary and a devastating wildfire that consumed a third of Jasper, Alta.

On Tuesday, Environment and Climate Change Canada released its own look back over the previous year and noted that temperatures were “above normal” in every region of the country.

Canada is a signatory to the 2015 Paris Agreement, an international treaty that was established with the goal of keeping global warming “well below” two degrees while pursuing efforts to limit the temperature increase to 1.5 degrees.

But Canada has struggled for years to meet its own climate goals in support of the agreement. Indeed, the politics of the moment suggests the country could soon be heading in the opposite direction, potentially following the United States, where president-elect Donald Trump has consistently voiced support for expanding domestic fossil-fuel production and dismantling climate measures enacted by the Biden administration.

And while the fires in Los Angeles offer a stark warning about where such a policy is projected to lead, the burden of climate change is now unequivocally being felt around the planet.

The European release noted that at maximum last year, 44 per cent of the globe was affected by “strong to extreme heat stress.” The total amount of water vapour in the atmosphere also reached a new record value, with high humidity levels contributing to the health risk of high heat and the likelihood of extreme precipitation events.

“It is clear we are now living in a very different climate from that which our parents and our grandparents experienced,” said Dr. Burgess during an online press briefing.

The conclusions of the report were confirmed by the UK MET Office in a separate release on Thursday. Similar results are expected from a briefing scheduled for Friday by NASA and the National Oceanic and Atmospheric Administration.

Ivan Semeniuk
Science Reporter
The Globe and Mail, January 9, 2025