The world's most important climate science body has left its biggest decision on the table. Late on Friday night in Addis Ababa, Ethiopia, IPCC Chair Jim Skea suspended the 65th plenary session of the Intergovernmental Panel on Climate Change after a week of talks failed to produce consensus among the panel's 195 member states on when its next major climate science assessment will be published.
The talks ran past their scheduled end, and by the time the final gavel was expected to fall, many delegations from the least developed countries and small island states had already flown home. Skea's own statement from the IPCC said the timelines for the three working group reports of the Seventh Assessment Report (AR7) — along with the IPCC's budget — "remain open," and that the suspended session would resume "at the earliest opportunity." No new date was set.
This is not a routine procedural hiccup. The argument over the report schedule has dragged on for nearly three years, survived five straight sessions without being resolved, and now threatens to leave the next round of global climate negotiations without the latest science at the very moment it is needed most. Countries are split down the middle: should the next landmark review come out in 2028, or wait until 2029?
What happened in Addis Ababa
Setting the publication dates for the next big review of the latest climate science was the main item on the agenda in the Ethiopian capital this week. The scientists who lead the three working groups proposed getting all three reports approved by September 2028 — a schedule that would put them on the table in time for the UN's big review of global climate progress in November 2028.
But a group of countries including India, Saudi Arabia, China, Russia and Kenya pushed back hard, arguing for more time. Plans based on Saudi and Indian proposals would push two of the three reports into 2029, giving scientists and governments from less-resourced countries more time to contribute.
On the other side of the argument stood a coalition of around 30 countries — including European, Latin American and small-island states — alarmed at the prospect of the reports arriving late. The possibility that the IPCC's reports might not be ready in time for the 2028 climate talks drew some of the sharpest reactions from the Pacific. "We were here to work, but found every proposal dismissed — on inclusivity, on the relevance of the science for our national planning, on the necessity of evidence to inform the next Global Stocktake," said Tina Stege, climate envoy for the Marshall Islands, after the suspension.
IPCC Chair Jim Skea himself warned that the stalemate carries organizational and reputational consequences for the panel — an unusually blunt public admission from a body that guards its credibility carefully.
What these reports actually are — and why the date matters
The IPCC was established in 1988 by the United Nations Environment Programme and the World Meteorological Organization to give political leaders periodic, rigorous scientific assessments of climate change, its risks, and how the world can adapt and cut emissions. Thousands of experts around the world volunteer as authors, assessing the thousands of scientific papers published each year.
Its big comprehensive assessments arrive every five to seven years, and they are the gold standard of climate science. The Seventh Assessment Report — AR7 — will have three massive working group contributions: Working Group I on the physical science of climate change, Working Group II on impacts, adaptation and vulnerability, and Working Group III on how to cut emissions. Alongside them, governments have already agreed on a special report on climate change and cities, plus methodology reports, and an overall synthesis report that would follow by late 2029.
The last round of these reports, AR6, was published in three parts in 2021 and 2022 and delivered an increasingly stark message: unless emissions were cut swiftly, the world would face impacts that are swift, severe and in some cases irreversible. AR7 is expected to strike an even more urgent note — greenhouse gases have kept rising since AR6, and extremes such as record heat, floods and droughts are becoming visibly more severe.
That is exactly why the publication date is not a bureaucratic detail. The reports are meant to assess the very extremes the world has just lived through — including the record-shattering 2026 super El Niño and what it means for the years ahead, and events like how Hurricane Simon sent invisible gravity waves rippling across the globe this season. Every month of delay means the science that feeds the next global review is a little older, and a little thinner.
2028 versus 2029: who wants what, and why
On paper, both camps say they are defending the interests of the developing world — and both have a point worth hearing.
The 2028 camp argues that timing is everything. The scientists' proposal would see all three working group reports approved by September 2028, leaving them ready to feed into the second Global Stocktake of the Paris Agreement — the formal check on whether countries are doing enough — which wraps up at the UN climate conference in November 2028. More than 30 ministers and a broad coalition of governments insisted on this timeline and criticized attempts to delay. Pacific civil society went further, calling September 2028 the latest acceptable deadline, warning that denying vulnerable communities the science denies them a future.
The 2029 camp argues that speed without fairness produces weaker science. India, Saudi Arabia, China, Russia and Kenya — backed by many other developing countries — say scientists and governments from less-resourced nations need more time to review the literature, write chapters and take part meaningfully in the review process. "Scientific urgency and equity must go hand in hand," said Meena Raman of the Third World Network's Demand Climate Justice campaign. "Without sufficient time and resources, the inequalities in participation that already exist risk being perpetuated."
Here is the uncomfortable truth: both sides are right. The IPCC's credibility rests on being both timely and genuinely global. Rush the science and you weaken its authority and fairness; delay it and you weaken its usefulness. The problem in Addis Ababa was that the consensus system gave neither side a way to give ground.
The stakes: the November 2028 Global Stocktake
The Paris Agreement's ambition engine is the Global Stocktake — a periodic moment when the world stops, measures progress against its climate goals, and is supposed to ratchet up its efforts. The first stocktake concluded at COP28 in 2023. The second is a carefully choreographed three-act process: information collection begins at COP31 in Antalya in November 2026, the technical assessment runs from June 2027 to June 2028, and the political phase — where the real pressure is applied — culminates at COP33 in November 2028.
If the AR7 reports slip past that window, negotiators at COP33 will have to decide the next phase of climate action without agreed, up-to-date science on critical questions — including, as Reuters reported, the extent to which some global warming might be reversible. Analysts have warned the disconnect could be historic: a compromise timeline discussed by IPCC co-chairs could still have placed the first working group report inside the technical phase and the other two in time for the political phase at COP33 — but only if governments agreed now. Climate Analytics has warned that reports arriving after the stocktake would mark a "major historical break" that could be used to weaken the Paris process.
After the UN's warning that the "war on nature" is raging on ahead of COP17 showed how far implementation lags behind promises, arriving at the biggest review of the Paris Agreement without fresh science would be a damaging signal.
The missing superpower
There is a shadow hanging over all of this that goes beyond scheduling: money. The United States — historically the IPCC's biggest funder — quit the panel in January 2026. The meeting in Addis Ababa also failed to agree on the IPCC's budget, including the budget for 2027, and the budget talks are directly tied to the timeline decisions.
This is not an abstract accounting dispute. The budget pays for the machinery that produces the reports — author meetings, review timelines, and the funding that lets scientists and delegates from poorer countries take part. The irony is sharp — one side demands more time so developing countries can participate, while the funding that would make that participation possible is itself unresolved and shrinking.
A "consensus machine" breaks down
Perhaps the most remarkable thing about the Addis Ababa breakdown is how unusual it is. The IPCC makes its big decisions by consensus, and it has a long record of doing so. As Leo Meyer put it, the panel has long functioned as a "consensus machine" — making this open disagreement highly unusual.
That consensus rule is the IPCC's greatest strength and, right now, its greatest vulnerability. When every one of 195 member states effectively holds a veto, a handful of governments can block the whole panel. Skea's decision to suspend rather than force a vote was framed as protecting inclusivity — the meeting ran so far over its planned duration that many of the smallest, poorest delegations had already left, and deciding without them would have broken consensus itself.
What happens next
The official line is that the 65th session and the panel's deliberations will resume "at the earliest opportunity." Unofficially, everything is up in air. No date has been set, and with the budget unresolved and the timeline dispute now nearly three years old, there is no guarantee the next attempt goes more smoothly than the last five.
Here is what to watch:
- When the new date is announced. Campaigners are urging the panel to reconvene quickly, but the longer the gap, the harder the 2028 timeline becomes to keep — every month of delay narrows the scientists' window.
- Whether a compromise emerges. A middle path discussed earlier could still land the first working group report inside the stocktake's technical assessment phase, with the other two arriving in time for the political phase at COP33. That option only works if governments agree soon.
- COP31 in Antalya, November 2026. The stocktake's information-collection phase starts there. If the IPCC still has no agreed schedule by then, the 2028 timeline will be under severe strain.
The deeper lesson of Addis Ababa may be the hardest one. The IPCC was built on the belief that rigorous, consensus-based science can guide politics. This week, politics — in the form of an unbreakable deadlock — stopped the science instead. The climate itself, of course, will not wait for the scheduling dispute to be resolved. Every year of extreme weather that goes unassessed is a reminder of what is at stake when the world's climate science machine stalls.