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 finalise 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 success of the Glasgow climate conference in November,” he said.

Record-smashing heatwaves, 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 prepared statement.

A key G20 summit with climate on the agenda is slated for late October.

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 almost entirely human in origin, along with the falsely reassuring notion that climate impacts are tomorrow’s problem, have since evaporated in the haze of deadly heatwaves and fires.

Another milestone since the last IPCC tome: the Paris Agreement has been adopted, with a collective promise to cap the planet’s rising surface temperature at “well below” two degrees Celsius (3.6 degrees Fahrenheit) above late-19th century levels.

Carbon pollution from burning fossil fuels, methane leaks and agriculture has driven up the thermometer 1.1 degrees Celsius so far.

The 2015 treaty also features an aspirational limit on warming of 1.5 degrees Celsius, with many parties no doubt assuming this goal could be safely ignored.

But an IPCC special report in 2018 showed how much more devastating an extra 2 degrees Celsius would be, for humanity and the planet.

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