The Intergovernmental Panel on Climate Change's new report on the 1.5 Celsius temperature limit makes for somber reading. In the pages of this document, you'll discover that humans have so far caused around one degree Celsius of global warming over pre-industrial levels, that the planetary costs of exceeding 1.5 degrees are devastatingly high, and that, unless the world takes action on an historically unprecedented scale, we will overshoot this goal.
The United Nations' climate body requested this report in 2015 when it adopted the Paris Agreement. This international deal cemented for the first time—albeit in rather aspirational language—the urgency of limiting global temperature rise to 1.5 degrees, rather than the two-degree limit that had been the nucleus of climate talks since 2010.
In other words, the decision to author the climate report was made by politicians and diplomats, not scientists. And while many climate observers have welcomed the attention to this once-fringe goal, others have questioned the usefulness of the endeavor. While its urgent message grabbed headlines around the world (competing, with limited success, against Taylor Swift's political awakening in the United States and a Strictly Come Dancing scandal in the United Kingdom), some scientists were asking: Is this a waste of our time?
Between reading the IPCC report and perusing world news, it's hard to believe that the 1.5-degree limit could ever be more than a pipe dream. In the U.S., the Trump administration poses an obvious obstacle to any semblance of federal climate action, but America is hardly alone in dashing any hopes of meeting this goal. In Brazil, voters look ready to elect far-right candidate Jair Bolsonaro as president, a man who has promised to abolish the country's environment ministry and withdraw from the Paris Agreement. The U.K. is set to start fracking for the first time in seven years. Australia's prime minister has refused to provide further money to the U.N.-backed Green Climate Fund.
These political decisions are taking place in a context of action that's already insufficient. To limit warming to 1.5 degrees Celsius, emissions need to decline by about 45 percent compared to 2010 levels by 2030, and reach net zero by 2050. The nationally determined contributions set under the Paris Agreement won't achieve the necessary reductions.
"The question is: Will policymakers change their behaviors based on this report? They asked for the report, they got the report, so now what are they going to do? I think the answer is they'll do nothing," says Glen Peters, a climate scientist at CICERO, a Norwegian institute. "After the Paris Agreement, when 1.5 degrees Celsius was mentioned in the target, countries didn't quickly come around and say, 'Well, it's gone from two degrees to 1.5 degrees, now we're going to raise our ambition.' So I don't think countries are going to come running and say, 'Well, we've seen the report now, the science is out, we're going to increase our ambition.' That's just not going to happen."
Climate scientists also point out that the report is not necessarily valuable as a standalone contribution to scientific knowledge. The IPCC works to synthesize, rather than generate, results.
"The UNFCCC is not necessarily interested in moving the science forward, but rather about what the science says about a question that they care about. Does this report move the science forward? I don't think so," says Gavin Schmidt, climate scientist and director of the NASA Goddard Institute for Space Studies. Nonetheless, he hopes that it could help to create a more sustainable conversation around the subject of the 1.5-degree goal among climate-aware politicians and local governments, even if the Trump administration is likely to ignore it. "I would say this is likely to be more politically useful than scientifically useful."
The value of generating an in-depth report on an almost-impossible target has raised concerns about the opportunity cost, and whether this was really the best use of climate scientists' time. Peters says that he'd liked to have seen researchers devote the time they spent working on the IPCC report instead to exploring, for instance, how to reach more realistic goals in light of political realities, and examining what policies work best in tackling climate change, "as opposed to just generating another bunch of scenarios that have lines that are a little bit steeper than the last bunch of scenarios."
But Ruth Mottram, a climate scientist at the Danish Meteorological Institute, says that, while she'd been dubious about the report, reading it changed her mind. "I was very skeptical about it at first because it seemed like a massive waste of time, but actually I don't think it has been a big waste of time," she says. In focusing minds on the 1.5-degree target, the report opens up important scientific questions on "overshoot scenarios", such as whether the Greenland ice sheet would re-form if temperatures rose beyond 1.5 degrees and then returned to the present climate. "Probably it wouldn't," she says.
Another question is whether the very existence of this report represents a sacrifice on the part of developing countries—and whether it was worth it. In the fractious 2015 negotiations of the Paris Agreement, vulnerable nations effectively entered a trade-off with developed nations, agreeing that the Paris Agreement "does not involve or provide a basis for any liability or compensation" in exchange for moving the discussion forward on the question of 1.5 degrees.
"At that moment, we had to take a call whether we remain fixed on demanding compensation or to allow the whole issue to make progress, which is what we have seen," says Harjeet Singh, global lead on climate change for the non-profit ActionAid, adding that the past few years have seen accelerated action on displacement and finance for loss and damage. "It's desirable to have it from a body that's respected and the ultimate authority on climate science. There should not be any further debate on why it's so important to stay below 1.5. What you need is just the political will to achieve that."
The report, Singh adds, has come at an important juncture in the U.N. climate process, given the U.N.'s focus this year on taking stock of the current climate pledges and preparing for the next round—an important stage in the process of ratcheting up ambition over time.
There is also a moral dimension to preparing this report, says Achala Abeysinghe, an advisor to the U.N.'s Least Developed Countries group. "[Climate risks] fall worst on the poorest in the world despite them not having contributed to the problem. This report captures all these and therefore adds a heavy moral value to the conversation and the climate change fight."
Focusing on the radical pathways to keep warming below 1.5 degrees is helpful in the long run, Schmidt adds.
"It's not the worst thing in the world to be aspirational," he says. "We're aspirational about a lot of other things. The Sustainable Development Goals are aspirational. People are trying to make them come through, but those working in the field are realistic. You don't expect everything to go to zero, but you try to minimize the impacts as much as you can."
Was the report a waste of scientists’ time, or a valuable contribution? The proof will lie not within the pages of the IPCC report itself, but rather in the actions it spurs now that it's in front of politicians. For the vulnerable countries for whom the 1.5-degree goal is a matter of life or death, it offers a further and chilling substantiation for their concerns.
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