(Bloomberg) -- The last time the United Nations-backed consortium of climate experts released a special report—Global Warming of 1.5°C in 2018—it set off a swift chain of consequences. Protest movements erupted seemingly overnight. The term “net zero” was suddenly commonplace. Nearly three years later, most of the current momentum behind climate action can be traced back to that report.

The diplomats and scientists who make up the Intergovernmental Panel on Climate Change, as the group is known, are right now meeting by video conference to hammer out their next report, due to be released Monday. It’s a much bigger undertaking, representing a total refresh of the global consensus on climate science for the first time since 2013. For the 234 authors, the process involves synthesizing more than 14,000 studies and, crucially, winning the sign-off of the group’s 195 member countries, any one of which could block key conclusions from appearing in the report’s “summary for policymakers,” the only part most people will read.

That makes it vulnerable to politics—especially the politics of the world’s biggest oil exporters. The IPCC got an object lesson in this risk in 2018, when Saudi Arabia tried at the last minute to defang the 1.5° Celsius report.

When countries signed on to the 2015 Paris Agreement, they pledged to keep warming “well below” 2°C compared to pre-industrial times while also “pursuing efforts” to limit it to 1.5°C. It wasn’t clear what exactly the world would have to do to meet the more ambitious goal. So governments, in the language of diplomacy, “invited” the IPCC to provide an answer.

This was a highly unusual request. The IPCC is an association of volunteer scientists who produce arduous technical assessments, not policy recommendations. The scientists responded by determining that the consequences of 2°C of warming would be significantly worse than those of 1.5°C. Keeping the world at 1.5°C would require that nations halve their emissions of CO₂ by 2030 and eliminate them completely by 2050.

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All of this went into a draft of their report for a meeting of the IPCC scientists and climate diplomats at a summit in Incheon, South Korea, spanning the first week of October 2018. Negotiations followed their usual rhythm—by turns grinding, grandiose and ponderous—under the rising intensity of a ticking clock to the deadline.

With just 24 hours to go, Saudi Arabia brought the production to a halt when it moved to strike language from one of the report’s headline statements. The paragraph in question explicitly called out “nationally determined contributions”—the official name of countries’ climate goals—for not meeting the Paris Agreement’s 1.5°C goal. Saudi negotiators wanted to remove references to national policy statements and the Paris Agreement from the full 616-page report.

The IPCC’s “products must be policy-relevant and policy neutral and not policy-prescriptive,” the Saudi delegation said in an official statement published after the event. The problem, said David Victor, a climate policy expert at the University of California at San Diego, is that the difference between “relevant” and “prescriptive” has never been defined. 

“There aren't clear guardrails for containing objections by countries,” Victor said in an interview this week, particularly when the concern is that the IPCC is blurring the line between informing and influencing policy.

Scientific statements that concern “which kinds of government policies work or don't work very quickly shades into things that could be branded by somebody as policy-prescriptive,” Victor said. “And then they're in a no-fly zone.”

The Saudi delegation had Egypt’s backing when it objected on the second-to-last day to any mention of NDCs, according to a summary of the proceedings published in Earth Negotiations Bulletin. A compromise to strike “NDCs” while keeping “Paris Agreement” was no good either, as the same point was implied.

“This is IPCC high theater,” said Piers Forster, a University of Leeds climate physics professor, remembering that day’s events recently.

New language presented on the final day of the Incheon conference stirred disagreements from the island nations of Saint Kitts and Nevis, Grenada and the Marshall Islands, with support from Belgium and France. The U.S., on its way out of the Paris Agreement under then-President Donald Trump, filed an official statement clarifying that it didn’t endorse the report. 

There was no consensus. When that happens, IPCC rules mandate that the competing views be explained and officially recorded, on request. The scientists had the final word—and that meant explicitly mentioning the Paris Agreement and paraphrasing NDCs as “current nationally stated mitigation ambitions.” It was “the most appropriate wording for conveying the science,” said Forster.

Whether the standoff and altered phrasing had any impact on how the report was received is hard to judge. The report has become a rallying cry for climate-focused activists, investors and policymakers around the world. Most large emitters from China to the U.S. have committed to some kind of net-zero goal. And yet, as of July 31—the deadline for submitting plans to cut emissions—only 110 had submitted plans to the UN. Major economies including China, India, Saudi Arabia and South Africa have yet to meet the requirement set under the Paris Agreement.

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Saudi Arabia signed the Paris Agreement, yet it’s remained a skeptical voice at most international climate forums, for the most part. The world’s largest producer of oil is still figuring out what its economic future will look like once global consumption of fossil fuels starts to decline. That’s one of the main goals of Crown Prince Mohammed bin Salman's ongoing diversification program, Vision 2030. But in the meantime, the Saudi government’s main aim appears to be ensuring that it’s the last oil producer standing.

Saudi Arabia now also wants to be seen as a facilitator of a global agreement to address climate change—one that still allows it to sell its oil. During its presidency of the Group of 20 nations last year, Saudi officials succeeded in introducing the phrase “circular carbon economy” into the energy and climate communiqué. The concept is a nod to the necessity of carbon removal that still allows carbon-based fuels to be used on a reduced basis, as long as what they do emit is captured and recycled. At this year’s G-20 meeting, Saudi negotiators attempted to broker an agreement that allowed the communiqué to be published, while helping move India’s objection to a footnote.

For its part, the UN-backed science group won't disclose details of the diplomatic maneuvering over its work. “The IPCC isn’t in a position to comment on the positions that its member governments take in approval sessions of its reports,” a spokesperson for the group said this week.

The report due to be published on Monday is expected to stay away from discussions of national emissions goals, and that might mean less drama on country-level deliberations. Subsequent reports on climate impacts, adaptation, and mitigation are expected next year.

The final text will no doubt be dry and technical, belying whatever ugly fights may be happening behind the scenes. But scientific terminology and diplomatic phrasing will be hard-pressed to mask the increasingly obvious impact of warming temperatures.

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