Science agencies in the US and Europe this week released their temperature data for 2022, revealing what has become an annual headline: Last year was one of the hottest on record. 2022 tied for fifth hottest, according to NASA. The US National Ocean and Atmospheric Administration, which uses slightly different data, said it came in sixth.
That’s even though La Niña cooled the equatorial Pacific, which typically turns down global temperatures.
“This was, in fact, the warmest La Niña year in the whole record,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies.
Earlier this week, Europe’s Copernicus Climate Change Service revealed 2022 was that continent’s second-hottest year ever, and hottest summer.
Last year was about 2 degrees Fahrenheit hotter than the preindustrial average, or 1.1 or 1.2 degrees Celsius, depending on whose data you use. That’s edging closer and closer to 1.5 degrees Celsius, a limit most countries in the world have pledged not to exceed. That goal is written into the 2015 Paris climate change agreement, alongside a less-ambitious target of limiting warming to “well below” 2 degrees Celsius. But it’s the lower target that has taken hold in recent years as both a goal and a rallying cry for aggressive climate action.
Keeping 1.5 “alive” became the mantra of Alok Sharma, the UK politician who served as president of the COP26 climate summit in Glasgow in late 2021. UN Secretary General António Guterres also frequently references the figure, among many others.
A coalition galvanized by low-lying island nations lobbied to get the more-ambitious target written into the Paris climate deal, arguing that exceeding that threshold represented an existential threat for their counties.
"It means we are dead. Just simply dead," former Maldives President Mohamed Nasheed told The World in 2021. “A whole country gone. A whole people gone. A whole society gone. A whole community gone. And this is the case with many, many low-lying islands.”
That target has always been wildly ambitious. But in the last seven years, as carbon emissions have continued to rise, it has gotten even more so. Global greenhouse gas emissions would need to be slashed 45% by the end of this decade to meet it, and a UN report published in October said there was no “credible” pathway to 1.5 in place.
Many climate scientists say that they don’t believe the target will be met.
“I'm pessimistic for the 1.5,” said Thomas Stocker, a climate scientist at the University of Bern who co-led an Intergovernmental Panel on Climate Change report on the physical basis of climate change in the years leading up to the Paris agreement’s creation.
“We're not on the pathway to actually keep the warming at 1.5 degrees Celsius,” he said. “We [would] be extremely lucky to hold the temperature warming below 2 degrees.”
Three scientists involved in tracking the global temperature data that was released this week also said they saw limiting warming to 1.5 degrees Celsius as unlikely.
“I think it's very challenging to stay below 1.5,” said Schmidt, saying he was speaking only for himself, not NASA.
“My expectation is that we will hit 1.5 degrees sometime in the 2030s,” said Samanath Burgess, deputy director of Europe’s Copernicus Climate Change Service.
“I think it's very unlikely that we avoid overshooting that level of warming,” said Zeke Hausfather, with Berkeley Earth, an independent research group that also released its 2022 temperature data on Thursday.
It’s technically still possible to keep warming at 1.5 degrees, according to the science of atmospheric warming. But a recent IPCC report shows it would require a massive shift away from coal, oil and gas at a speed that’s hard to imagine. And it almost certainly would require overshooting the 1.5 limit for a time, then removing carbon from the atmosphere again before the end of the century to bring the globe’s average temperature back down.
Still, Hausfather said he thinks that the goal itself has been useful.
“Even if it's a target we don't hit, I feel like the fact that we are trying means we'll probably end up in a better place than if we were aiming higher,” he said.
Hausfather points out countries responsible for around 80% of emissions now have targets to reach net-zero emissions by midcentury. Whether they meet them, of course, is an entirely different question, but the goal itself is based on the science behind the 1.5-degree goal.
The target being written into an international agreement “holds political leaders accountable,” Burgess said.
Even as 1.5 continues to be held up as the goal by political leaders and activists, scientists aren’t exactly shouting from the rooftops how much of a stretch it really is.
Swiss scientist Thomas Stocker said there’s a concern that doing so would stymie ambition.
“I disagree,” he said, arguing it should instead galvanize even faster action.“The consequence should be that under no circumstances will we lose the second target and make the same mistakes again.”
Some scientists worry that the 1.5-limit has been framed as a kind of tipping point, a make-or-break goal.
“The reality is that every single fraction of a degree matters; 1.5 isn't a cliff edge where bad things will happen. Bad things are already happening,” Burgess said.
Keeping warming below 1.7 degrees, say, would be better than 1.8 — 1.9 would be better than 2.
Each 10th of a degree could cause more extreme rainfall, like the kind flooding California right now, and worsen heat waves, droughts and hurricanes, and further push up sea levels imperiling low-lying island nations.
Leaders and activists in those vulnerable countries largely are not ready to talk about a post 1.5-world, at least to reporters.
"I can't afford to think that 1.5 degrees is not attainable," former Maldives President Mohamed Nasheed said in 2021. “That would be a death sentence on our countries, and many low lying islands and coastal regions.”
With current pledges made under the Paris agreement, the UN Environment Program estimates the world is on track for 2.4 to 2.6 degrees Celsius of warming by century’s end.
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