Major economies have resisted calls for bolder climate commitments as a UN summit in Madrid limps towards a delayed conclusion.
With the two-week gathering spilling into the weekend, campaigners and many delegates slammed Chile, presiding over the talks, for drafting a summit text they said risked throwing the 2015 Paris Agreement into reverse.
“At a time when scientists are queuing up to warn about terrifying consequences if emissions keep rising, and school children are taking to the streets in their millions, what we have here in Madrid is a betrayal of people across the world,” said Mohamed Adow, director of climate and energy think-tank Power Shift Africa.
The annual climate marathon had been due to conclude on Friday, but dragged on with ministers mired in multiple disputes over implementing the Paris deal.
The Paris agreement has so far failed to stem the upward march of global carbon emissions.
Long-time participants in the talks expressed outrage at the unwillingness of major polluters to show ambition commensurate with the gravity of the climate crisis, after a year of wildfires, cyclones, droughts and floods.
The EU, small island states and many other nations had been calling for the Madrid decision to signal that the more than 190 countries participating in the Paris process will submit bolder pledges to cut emissions next year.
The agreement enters a crucial implementation phase in 2020, when countries are supposed to ratchet up their ambitions ahead of the next major round of talks in Glasgow.
If big economies such as China, India, Japan, Brazil, Australia and others fail to agree to more meaningful climate action soon, then scientists say already slim hopes of averting catastrophic temperature rises will all but vanish.