Governments have delayed for the third time a key decision on the timing of an influential climate science assessment, after failing to resolve deep divisions at a meeting of the Intergovernmental Panel on Climate Change (IPCC) over whether and how to align its work with UN climate policy.

While officials agreed on the outline of the IPCC’s three flagship reports in Hangzhou, China, on Saturday, they failed to break the deadlock on when they should be delivered, despite week-long talks running into overtime with a nearly uninterrupted 30-hour session on the closing day.

Most governments spoke in favour of a proposal put forward by the IPCC’s administrative arm to conclude the scientific review process by August 2028, so that the reports would be ready in time to be considered as part of the “Global Stocktake”, a scorecard of climate action carried out under the Paris Agreement. European nations, Japan, Turkiye, small island states and most Latin American and least developed countries supported the plan, three delegates told Climate Home.

But China, Saudi Arabia and India strongly pushed back against that timeline, while South Africa and Kenya asked for further discussions to bridge concerns over the inclusivity of the process, the sources added.

At the eleventh hour, the Chinese hosts of the summit brokered an interim deal that will kick-start the assessment process in 2025, while discussions over the deadline for completing the reports will resume again at the next IPCC session later this year, for which there’s still no fixed date.

“Despite the heavy agenda, thanks to the Panel’s ability to build and achieve multilateral consensus, and the tireless work of the IPCC’s Scientific Bureau, we now have clarity on the scope of the scientific content,” IPCC chair Jim Skea said at the end of the meeting.

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Climate policy alignment

The IPCC is in its seventh assessment cycle – known as AR7 – which is tasked with compiling global climate science into three reports: one on the physical scientific basis of climate change, another on the vulnerability of human and natural systems, and a third on options for mitigating the emissions that are heating up the Earth’s climate.

The IPCC’s sixth assessment played a key role in informing the first Global Stocktake in 2023 which culminated in countries committing for the first time to “transitioning away from fossil fuels in energy systems” at COP28 in Dubai.

China’s role as the host of last week’s summit was under the spotlight as observers looked for signs of leadership on global climate action as the US retreats from international climate diplomacy under Donald Trump.

At the start of the meeting, Liu Zhenmin, China’s Special Envoy for Climate Change, praised the contribution of the climate science community in informing policy responses.

“Upholding multilateralism and strengthening global climate action is the only way forward. I hope the IPCC and the UNFCCC will continue to work together in an orderly manner to advance human climate action,” he added.

But three delegates told Climate Home of a disconnect between public statements from Chinese officials and negotiating positions in closed meetings where, they said, China reinforced its national priorities.

They added that China – and some other high-income developing nations – seem keen to keep the IPCC reports out of the next stocktake as they fear the scientific findings would put them under mounting pressure to curb greenhouse gas emissions.

“Failing to reach a decision on the AR7 timeline only serves those who wish to hold back climate action, but climate vulnerable countries cannot wait,” said Zhe Yao, global policy adviser at Greenpeace East Asia, who attended the meeting. “It’s a bitter disappointment every time division leads to a decision being postponed or kicked down the road”.

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Concerns over keywords removal

Technical discussions over what the IPCC reports should deal with took up the majority of the week-long session in Hangzhou.

Diana Urge-Vorsatz, a Hungarian scientist and vice-chair of the IPCC, criticised efforts to remove “key scientific concepts” from the outlines which, she said, creates concerns over the future of global climate science.