Optimistic vs. 'No Backbone': Scientists Split on Whether Climate Pact Will Meet Goals

In the aftermath of COP26, scientists are torn over whether the U.N. Climate Summit's final pact will be enough to combat climate change. Many scientists are split on the effectiveness of the proposed 1.5-degree Celsius limit. The Associated Press spoke with 13 scientists after the pact was revealed at COP26, and they responded to the new venture with varying reactions. Some scientists are cautiously optimistic about the new deal, but it will have to take a lot of work from the countries involved to make it a reality. Pennsylvania State University climate scientist Michael Mann is one such scientist, who said that he "can really see a potential path forward to limiting warming to 1.5C." However, he warns that "it will require both (a) countries making good on their current pledges and (b) further ratcheting up their current commitments." However, some scientists think that the ultimate deal was too little, too late. Intergovernmental Panel on Climate Change co-chair Hans-Otto Portner said the conference "got work done, but did not make enough progress." He particularly criticized the 1.5-degree limit proposed at the conference. He elaborated on this by saying, "warming will by far exceed 2 degrees Celsius. This development threatens nature, human life, livelihoods, habitats and also prosperity." Other scientists were more condemning in their responses. Jonathan Overpeck of the University of Michigan's environment school wrote AP, saying that he went into the conference "thinking 1.5C was still alive, and it appears the world's leaders just didn't have the backbone for that." Almost 200 nations accepted the compromise deal at COP26. For more reporting from the Associated Press, see below.

"In the bigger picture I think, yes, we have a good plan to keep the 1.5-degree goal within our possibilities," United Nations climate chief Patricia Espinosa told AP, referring to the overarching global goal of limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) since pre-industrial times. United Kingdom Prime Minister Boris Johnson, the conference host, agreed, calling the deal a "clear road map limiting the rise in global temperatures to 1.5 degrees." But many scientists are far more skeptical. Forget 1.5 degrees, they say. Earth is still on a path to exceed 2 degrees (3.6 Fahrenheit). "The 1.5C goal was already on life support before Glasgow and now it's about time to declare it dead," Princeton University climate scientist Michael Oppenheim told AP in an email Sunday. The optimists point to many agreements that came out of Glasgow, including a United States-China deal to work harder together to cut emissions this decade, as well as separate multi-nation agreements that target methane emissions and coal-fired power. After six years of failure, a market-based mechanism would kick-start trading credits that reduce carbon in the air. The 1.5-degree mark is the more stringent of two targets from the historic 2015 Paris climate accord. United Nations officials and scientists consider it key because a 2018 scientific report found dramatically worse effects on the world after 1.5 degrees. The world has already warmed 1.1 degrees (2 degrees Fahrenheit) since pre-industrial time, so this is really about a few tenths of a degree more. The United Nations calculated that to limit warming to 1.5 degrees, countries need to cut their emissions in half by 2030. Emissions are now going up, not down, by about 14% since 2010, Espinosa said. Instead of big changes in bending the temperature curve as the United Nations had hoped for from Glasgow, they got only tiny tweaks, according to scientists who run computer simulations. "Heading out of Glasgow we have shaved maybe 0.1C off of warming ... for a best-estimate of 2.3C warming," Breakthrough Institute climate scientist and director Zeke Hausfather said in an email. Hausfather has done climate modeling with colleagues for Carbon Brief. MIT professor Jon Sterman said his Climate Interactive team crunched some preliminary numbers after the Glasgow deal came out and it didn't match leaders' optimism. "There is no plausible way to limit warming to 1.5 or even 2 (degrees) if coal is not phased out ... and as rapidly as possible, along with oil and gas," he said. On Saturday, India got a last-minute change to the pact: Instead of the "phase out" of coal and fossil fuel subsidies, the subsidies are to be "phased down." Several of the scientists said that regardless of what the deal says, coal needs to end, not just decrease, to lessen future warming. "'Lessening' will do less to slow the harmful effects of climate change than 'eliminating,'" former NASA chief scientist Waleed Abdalati, an environmental researcher at the University of Colorado, said in an email. Before the pact was finished, Climate Action Tracker, which also analyzes pledges to see how much warming they would lead to, said emission-cut pledges would lead to 2.4 degrees of warming. The 1.5 figure "is balanced on a knife edge," said tracker scientist Bill Hare of Australia.

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One paragraph in the pact — which calls on countries whose emission-cutting goals aren't in line with 1.5- or 2-degree limits to come back with new stronger goals by the end of next year — gives hope, Hare said. But U.S. climate envoy John Kerry said Saturday night that the paragraph probably doesn't apply to the United States, the second-largest coal emitter and the largest historically, because the U.S. goal is so strong. Some progress was made, said University of Illinois climate scientist Donald Wuebbles, one of the key authors of the U.S. national climate assessment. "But the probability of getting to 1.5 degrees is much reduced, even to the point of almost being impossible. Even being able to get to 2 degrees is less likely." Johan Rockström of the Potsdam Institute for Climate Impact and Research in Germany highlighted the "optimistic" scenario he and a few others see if all the countries that have promised net-zero emissions by mid-century actually achieve the goal — something on which most haven't started concrete action. In that case, warming could be limited to 1.8 degrees or 1.9 degrees, Rockström said. "That is a significant progress, but far from sufficient," he said.