Boris Johnson is to call on world leaders to commit to cutting greenhouse gas emissions and secure the planet for the next generation.
The prime minister will tell a meeting hosted by UN Secretary General Antonio Guterres that climate action “cannot be another victim of coronavirus”.
He will urge leaders to “look ahead to how we will rebuild” after the pandemic and how to “build back better”.
Mr Johnson is expected to speak to leaders via video link.
His speech at Thursday’s UN Climate Action Roundtable is part of the preparations for a global climate conference the UK is hosting in partnership with Italy in Glasgow in November next year.
The UN conference, known as COP26, is the most important round of climate talks since 2015, when the landmark Paris Agreement was secured, committing all countries to work to limit further rises in temperature.
Mr Johnson will also announce that the UK is to co-host an event with the UN on 12 December to mark the five-year anniversary of the Paris agreement.
The aim is that world leaders will use the December event to announce ambitious new targets for carbon reduction as part of the prelude to the Glasgow conference.
As part of the Paris Agreement all countries set their own targets for the reduction of greenhouse gas emissions.
Every five years they are supposed to announce new, more ambitious carbon reductions and set targets for when they will be able to reach what is known as “net zero emissions” – when greenhouse gas emissions are avoided completely or offset by planting trees or sucking CO2 out of the atmosphere.
Getting nations to agree to deeper carbon cuts is essential if the Glasgow conference is to achieve the UN’s aim of putting the world on track to keep global temperature rises below 2C.
“Look ahead to how we will rebuild, and how we can seize the opportunity to build back better,” the prime minister will say.
“Let us be the leaders who secure the very health of the planet for our children, grandchildren and generations to come.”
COP26 was due to have been held in Glasgow in November this year, but was postponed because of the coronavirus pandemic.
Mr Johnson wants to kick-start a year of action in the run-up to the climate conference.
He says he hopes the UK will serve as “a launch pad for a global green industrial revolution.”