"Today, #IPCC's latest #ClimateReport -- #ClimateChange 2021: the Physical Science Basis -- was approved and accepted in a historical first virtual approval session," the Intergovernmental Panel on Climate Change tweeted on Friday.

The report is set to be released on Monday.

IPCC delegates have been locked in virtual negotiations for two weeks, vetting a 30-page "summary for policymakers" - line-by-line, word-by-word -- of an underlying scientific report years in the making.

"This was such an amazing experience, so proud to be a small part of this great team and what we have achieved," German climatologist and IPCC contributor Friederike Otto said on Twitter.

On the heels of deadly floods in India, China and northern Europe as well as asphalt-melting heatwaves in North America and southern Europe, the IPCC's report assesses the latest climate science.

The world has changed since its last comprehensive assessment in 2014.

With increasingly sophisticated technology allowing scientists to measure climate change and predict its future path, the report is expected to make for harrowing reading.

It will project global temperature changes until the end of the century under different emissions scenarios.

Based almost entirely on published research, it could forecast -- even under optimistic scenarios -- a temporary "overshoot" of the 1.5C target of the Paris Agreement, and upwardly revised estimates for long-term sea-level rise.

It is also expected to reflect huge progress in so-called attribution science, which allows experts to link individual extreme weather events directly to man-made climate change.

While the underlying IPCC report is purely scientific, the summary for policymakers is negotiated by national representatives, and therefore subject to competing priorities.

Belgian climate physicist and former IPCC co-chair Jean-Pascal Ypersele, who was party to the negotiations, said the talks were guided by the underlying science.

"I can testify that the authors of the #ClimateReport had the last word on every sentence in the SPM, which really was a Summary FOR (and not BY) policymakers," he said on Twitter.

- 'Most important report' -

The report comes less than three months ahead of the COP26 climate talks in Glasgow, which are seen as vital for humanity's chance of limiting the worst impacts of global warming.

French climatologist Corinne Le Quere congratulated the delegates for finalising "the text of what I think will be one of the most important scientific reports ever published".

There will be two further parts to the IPCC's latest round of climate assessments, known as AR6.

A working group report on climate impacts, a draft of which was exclusively obtained by AFP, is set for release in February 2022.

Another on solutions for reducing emissions and adapting to climate change will be out the following month.