UN Secretary General Antonio Guterres has called on every country to draw up a clear roadmap for moving away from fossil fuels, warning that existing climate commitments would still leave the world facing more than 2C of global warming.
Speaking at a high-level climate meeting in New York, Mr Guterres said governments needed to accelerate the transition to renewable energy as the world heads towards an overshoot of the 1.5C warming threshold.
He said the emerging super El Niño was intensifying climate impacts while global greenhouse gas emissions were still rising when they needed to fall rapidly.
"The world is crying out for climate justice – in mitigation, in adaptation, in finance," he told political leaders attending the meeting.
"We must answer that call with action. And we don't have a moment to lose."
Mr Guterres said science now indicated the world was heading towards an overshoot of the 1.5C limit.
The priority must therefore be to make that overshoot "as small and as short as possible".
He strongly criticised the continuing expansion of fossil fuel production, adding that dependence on oil and gas was driving up costs and draining government budgets.
It was also leaving countries vulnerable to geopolitical conflicts and decisions made far beyond their borders.
"Doubling down on oil and gas will only lock in vulnerability for decades," he said.
By contrast, renewable energy has become the cheapest, fastest and most secure source of new electricity in almost every part of the world.
"Clean energy has gone from alternative to unstoppable," he said.
However, Mr Guterres warned that even if countries fully implement their existing national climate plans, the world would still be heading for warming of more than 2C.
He said that gap had to be closed during the current decade.
That would require a tripling of renewable energy capacity and a doubling of improvements in energy efficiency.
Countries also need to electrify their economies, cut methane emissions, halt deforestation and speed up the transition away from fossil fuels.
In this regard, he said that although all countries needed to increase their ambition, the G20 group of major economies had a particular responsibility to lead because they account for around 80% of global greenhouse gas emissions.
He insisted, however, that the transition must also be fair.
Workers and communities affected by the changes need to be directly involved, while developing countries need to share in the economic benefits, he added.
Mr Guterres said that if investment in climate adaptation is not greatly increased then droughts would become food crises, storms would become debt crises, and heatwaves would become increasingly deadly.
He called for climate adaptation funding to be tripled and for climate resilience to be incorporated into government policies, budgets and infrastructure decisions.
Mr Guterres said governments now needed to match the accelerating climate crisis with accelerating action.
"We are the first generation with the tools to end the fossil fuel age – and the last who can avert climate catastrophe," he said.
