The prime minister is delivering his keynote speech now, 12pm, today to more than 120 world leaders, hundreds of delegates, and a global audience of millions. Mr Johnson is expected to warn: "It is one minute to midnight and we need to act now." However, the Government may have an uphill battle on their hands to convince the world leaders to take the problem seriously after the G20 summit in Italy ended without an agreement to phase out coal consumption.

       The fruitless Italy summit caused United Nations Secretary-General António Guterres to reprimand the leaders and blast: “I leave Rome with my hopes unfulfilled.”

       If no serious commitments are made, the next 48 hours risks going down in history as a momentous failure by the international community to take action on climate change.

       A few hours ahead of the prime minister's rallying speech, Foreign Secretary Liz Truss admitted success was "touch and go".

       However, she admitted the next two weeks represented a "huge opportunity" to hold the attending world leaders to account.

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