Rich countries must sign a pact with poor countries on the climate or "we will be doomed" - that's the warning from UN secretary-general Antonio Guterres.
Speaking ahead of the COP27 climate summit in Egypt, Mr Guterres said wealthier countries must help emerging economies to speed up their transition to renewable energy.
"COP27 must be the place to close the ambition gap, the credibility gap and the solidarity gap," he said.
"It must put us back on track to cutting emissions, boosting climate resilience and adaptation, keeping the promise on climate finance and address loss and damage from climate change."
Rich countries have emitted more than their share of heat-trapping carbon dioxide by burning of coal, oil and natural gas.
Meanwhile, poorer countries like Pakistan, where recent floods affected 33 million people, have suffered more damage than their share of carbon emissions.
After last year's COP26 in Glasgow, the UN Environment Programme estimated that developing countries needed $70bn a year for adaptation - a figure expected to double by 2030.
Going into that summit, poorer nations again pushed for financial help from developed countries, calling for a loss and damage fund to compensate them for irreparable climate-related damage.
But the conference ended without a resolution - the $356m committed fell far short of what was needed for adaptation, and the loss and damage fund was rejected by wealthy nations.
Mr Guterres said that getting "concrete results" on loss and damage is the "litmus test of the commitment of the governments" involved in the summit.
He added: "Loss and damage have been the always-postponed issue.
"There is no more time to postpone it.
"We must recognise loss and damage and we must create an institutional framework to deal with it."
COP27 begins on Sunday in the Egyptian resort of Sharm el-Sheikh, running until 18 November.
It comes as greenhouse gas emissions are on course to rise by 10% and temperatures are set to rise by as much as 2.8C by the end of the century, Mr Guterres said.
"And that means our planet is on course for reaching tipping points that will make climate chaos irreversible and forever bake in catastrophic temperature rise," he added.
This is despite the 2015 Paris agreement calling for temperature rises to be limited to 1.5C, a goal he described as being "in intensive care", although it is "still possible to meet it".