Major economies resisted calls for bolder climate commitments as a UN summit in Madrid limped towards a delayed conclusion on Saturday, dimming hopes that nations will act in time to stop rising temperatures devastating people and the natural world.

With the two-week gathering spilling into the weekend, campaigners and many nations slammed Chile, presiding over the talks, for drafting a summit text that they said risked throwing the 2015 Paris Agreement to tackle global warming 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 Power Shift Africa, a climate and energy think-tank in Nairobi.

The annual climate marathon was supposed to conclude on Friday, but dragged on with delegates mired in multiple disputes over implementing the Paris deal, which has so far failed to stem the upward march of global carbon emissions.

Long-time participants in the talks were outraged 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 more ambitious 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 round of talks in Glasgow.

If big polluters such as China, India, Japan, Brazil, Australia and others fail to agree more meaningful climate action soon, then scientists say already slim hopes of averting catastrophic temperature rises will all but vanish.