United Nations Photo: VCG

Nearly 200 nations started online negotiations Monday to validate a UN science report that will anchor autumn summits charged with preventing climate catastrophe on a planetary scale. 

"The report that you are going to finalize is going to be very important worldwide," World Meteorological Organization head Petteri Taalas told some 700 delegates by Zoom.

The Intergovernmental Panel on Climate Change (IPCC) assessment "is critical for the Glasgow climate conference in November," he said.

Record-smashing heat waves, floods and drought across three continents in recent weeks, all amplified by global warming, have added pressure for decisive action. 

"For years we have warned that all of this was possible, that all of this was coming," the UN's climate chief, Patricia Espinosa, said in a statement.

Separately on Monday, the first face-to-face climate talks among governments in over 18 months showed real engagement and possible areas of compromise, officials said. 

However, the two-day ministerial meeting in London also laid bare differences, especially over the future of coal, which must be bridged before the COP26 summit in Glasgow. 

Britain's COP26 president, Alok Sharma, said the climate and environment ministers from more than 50 countries saw first-hand the changes afoot with torrential rain and flash floods hitting London as they met. 

The world is a different place since the IPCC's last comprehensive overview in 2014 of global heating, past and future. Lingering doubts that warming was gathering pace or that climate impacts are tomorrow's problem have since evaporated in the haze of deadly heat waves and fires.

From Monday, representatives from 195 nations, with lead scientists at their elbow, will vet a 20 to 30-page "summary for policymakers" line by line, and word by word.  

The virtual meeting for this first installment, covering physical science, of the three-part report will take two weeks rather than the usual one, with the document's release slated for August 9.

Part two of the report, to be published in February 2022, covers impacts.

A leaked draft obtained by AFP warns that climate change will fundamentally reshape life on Earth in the coming decades even if planet-warming carbon pollution is tamed, and calls for "transformational change" lest future generations face far worse.

Part three, to be unveiled the following month, examines solutions for reducing emissions.

Based almost entirely on published research, the report under review this week will likely forecast, even under optimistic scenarios, a temporary "overshoot" of the 1.5 C target.

There will also be a new focus on the so-called "low-probability, high-risk" events, such as the irreversible melting of ice sheets which might lead to sea levels rise by meters.

AFP