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THE MESSENGER: When the World Misses Climate Change Targets, This Is What Happens Next

A report released Thursday by the Overshoot Commission suggests how to manage a world where significant warming has already happened

By Dave Levitan | 14 September 2023

When the countries of the world signed the Paris Agreement in 2015, their ambitious goal of keeping warming to 1.5 degrees Celsius above pre-industrial levels was considered difficult, but achievable. Three years later, the Intergovernmental Panel on Climate Change’s report on the 1.5-degree target made the challenge more plain, warning that there were only about 12 years for the world to get its act together enough to meet the mark.

Five of those years are now gone, and today 1.5 degrees is looming large on the horizon. In July, new head of the IPCC Jim Skea said it is “absolutely for sure” that current government policies won’t come close to preventing it. Emissions, which need to be falling rapidly on the way toward net-zero at mid-century, stubbornly continue to rise. The odds of some massive shift in global fortunes within this decade seem slim. Enter the Overshoot Commission.

Overshoot refers to the idea that even on the way to a low-carbon economy and stabilization of global temperatures, we may push past 1.5 degrees —or the higher 2.0 degree target also set out in the Paris Agreement— before, hopefully, starting to head back down. The Overshoot Commission, composed of 12 commissioners from around the world, including former heads of state, wants the world to talk about how to avoid or manage that scenario. The commission released its first report on Thursday.

“It's an important discussion because the more we delay action on global warming, the higher the probability is that we do pass 1.5 and even the ‘well below two [degrees]’ standard,” said Chris Field, a professor and director of the Stanford University Woods Institute for the Environment, who also served as one of several science advisors to the commission. “It's not to say that anybody is supportive of decreasing efforts to meet the goals of the Paris Agreement, but just to recognize that the trajectory we're on doesn't inspire any level of confidence that we will.”

Impacts of 1.5 degree overshoot

A time period when the world has missed its climate goals, but is theoretically going to get there, would be a dangerous one. “Recent history has shown us a lot about what happens with each increment of warming,” Field told The Messenger. “Increasingly, we've seen heatwaves that just shattered records, and heavy precipitation events that are way outside the realm of historical experience. And that's what we'll see more of in the future.”

The report’s section on the impacts of overshoot reads like a horror story. “Areas currently on the margins of human habitability may become uninhabitable,” the authors wrote. “Ecosystems currently experiencing heat stress may not survive in their present form.” Human health would be severely at risk, marine ecosystems would collapse, extreme precipitation events would become commonplace.

“When we started, Pakistan was under water,” said Frances Beinecke, a commissioner and president emerita of the Natural Resources Defense Council, during a press conference in New York on Thursday. “Today, Libya is under water.”

The commissioners that addressed these impacts include representatives from five continents, and are divided between the Global North and South. It also took significant input from a youth engagement group, to reflect the danger to young people and future generations. That group had representatives from developing countries including Mauritius, Sri Lanka, and the Philippines.

“We are hoping for the best but we are also preparing for the worst,” said commissioner Arancha González, a former foreign minister of Spain and current dean of the Paris School of International Affairs at Sciences Po university. “Preparing for the worst is essential.”

Mitigation, adaptation and beyond

The report released on Thursday offers recommendations on several largely uncontroversial pieces of the overshoot puzzle, including mitigation and emissions reductions, and adaptation to current and future impacts. It tackles a few more thorny proposals, including carbon dioxide removal. And it takes on much, much thornier solutions, including solar radiation modification or solar geoengineering.

The idea, according to González, was to discuss all of this in a holistic fashion, instead of keeping everything siloed off. “It makes for a result that looks at where there are connecting points, where there are synergies, where there are commonalities,” she said.

Governance of the various approaches is one common thread, she said. For example, large-scale carbon dioxide removal, according to the report, will depend on government action, so the commission recommends expanded programs at the national level, with incentives to rapidly expand the practice.

Even if emissions drop to zero in a timely fashion, easing the planet back down toward its natural average temperature will require removing greenhouse gasses from the atmosphere. That will take huge amounts of forest and ecosystem restoration for natural storage of carbon, but also likely technological versions not yet ready for prime time.

“It hasn’t reached commercialization. It’s nascent, but a lot of the analysis says that we’re going to need to use it,” Beinecke said. “So how do we incentivize that and how do we ensure that the governance systems are in place to ensure that it works?”

When it comes to solar geoengineering, the idea of injecting large amounts of tiny sulfur particles into the stratosphere in order to cool the planet, the commission took a more cautious approach: The report recommends an immediate international moratorium on the large-scale deployment of geoengineering, but a wide expansion of research in order to better understand the risks and benefits.

“I think the climate challenges we face are so severe that we really ought to understand all the technologies,” Field said. There have been calls to stop research into solar geoengineering in recent years, on the argument that a cooling blanket around the world would give fossil fuel companies and petrostates permission to continue emitting, an idea known as mitigation deterrence.

“I feel like the opportunity to get key insights from the research is way more important than the risk that mitigation deterrence is unavoidable,” Field said.

González said that commissioners were generally aligned on this issue. “The reality is that the research is ongoing,” she said. “For me, it's very clear that this, today, should not be done. There should be a moratorium. Mostly because the unknowns are enormous.” But a carefully administered research program, with funding not from for-profit companies or any source with an interest in maintaining emissions, the report suggests, can cut down on those unknowns, and potentially offer a way to limit some of the suffering inherent to an overshoot scenario.

A litany of warnings

The urgency of the report’s message on a climate system threatening to tip over into a new, more disastrous state is not new, commission chair Pascal Lamy, a former director-general of the World Trade Organization, said on Thursday. Seemingly every week another such warning seems to emerge, whether it is a study on humans pushing the planet outside humanity’s “safe operating space” or the recent United Nations “global stocktake” that demonstrated how far the world's governments are off track.

But the commission hopes that the disparate ways a calamity might be addressed will now find “homes” in governments, international organizations and other fora around the world where they might be moved forward, González told The Messenger.

In the end, though, the report stresses that while carbon dioxide removal and geoengineering are worthy of discussion and study, and adaptation is critical, there really is only one answer.

“We have committed to the need to phase out fossil fuels, without any ifs, ands or buts or weasel words,” said commissioner Kim Campbell, a former prime minister of Canada, during a press conference on Thursday. “We have to do this… with overshoot hovering as a very distinct possibility in the near future.”


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