Some 60 world leaders are to convene on Monday for a UN summit on “climate emergency” aimed at reinvigorating the faltering Paris agreement, at a time when mankind is releasing more greenhouse gases into the atmosphere than at any time in history.

From heat waves to slow-crawling hurricanes to rapidly acidifying oceans, the impacts of global warming are being felt more than ever before, yet the gap between carbon reduction targets demanded by scientists to avert catastrophe and actions thus far taken is only widening.

It is within this context that a new, youth-led movement has emerged and re-energised climate activism, symbolised by Swedish teen Greta Thunberg.

Thunberg, along with millions of others around the world, rallied on Friday calling for climate justice and for the voices of the younger generations who will be most affected by increasing extreme weather events to be heard.

Fewer than half of the 136 heads of government or state in New York this week to attend the UN General Assembly will be present Monday.

Among the list of those absent will be US President Donald Trump, who pulled his country out of the Paris Accord upon taking power.

Likewise President Jair Bolsonaro of Brazil, under whose leadership the Amazon rainforest is continuing to burn at record rates, and Australian Prime Minister Scott Morrison, whose government has pursued an aggressively pro-coal agenda, are set to be absent.

China, the world’s biggest carbon emitter by far, but also a leader in the renewables sector, will be represented by foreign minister Wang Yi, with Guterres hinting last week that the country will be committing to new measures.

Indian Prime Minister Narendra Modi will speak in the morning session, along with the leaders of New Zealand, the Marshall Islands, and Germany’s Angela Merkel.

Like China, India is coal-dependent, but has also set itself highly ambitious renewable energy targets.

“We can hope for the best, that this group of progressive countries and actors and local authorities prepare for the second wave, to demonstrate that this is where modernity is, where progress is, and even where economic growth could be,” said Laurence Tubiana, CEO of the European Climate Foundation and one of the architects of the Paris agreement.