The King will tell world leaders on Friday that repeated warning signs about climate change are being ignored to the detriment of “lives and livelihoods”.
He will press upon those gathered at Cop28 in Dubai to take urgent action.
“I pray with all my heart that Cop28 will be a critical turning point towards genuine transformational action.”
The King will warn in his opening address: “The hope of the world rests on the decisions you must take.”
His Majesty is said to be “utterly focused” on official duties despite an ongoing furore in the UK over the naming of two members of the Royal family caught up in a racism row with the Duke and Duchess of Sussex.
As the only foreign head of state invited to address the summit, he is understood to consider his involvement a “great honour” and one that he “deeply appreciates”.
It is considered a testament to a lifetime of environmental campaigning.
‘We belong to the Earth’
The King will argue that while progress has been made towards a more sustainable future, the repeated warning signs of the impact of climate change, particularly in climate-vulnerable regions across the Commonwealth, are being ignored, with devastating consequences as “lives and livelihoods are laid waste”, and our shared future imperilled.
He is expected to say that the world needs real action and that solutions will only come if all nations work together. This should make it easier for the public sector, the private sector, philanthropic organisations and other stakeholders to unite in taking the necessary steps.
The King will also outline five key questions which he hopes Cop28 will address, helping to find solutions that will accelerate progress.
“The Earth does not belong to us, we belong to the Earth,” he will say.
The King began his 48-hour trip on Thursday with a 30-minute bilateral meeting with Bola Ahmed Tinubu, the president of Nigeria.
As they shook hands at a Dubai hotel, Mr Tinubu asked: “How are you?”
The King replied: “I’m all right very much, just about.
“Having had a rather ancient birthday recently recovering from the shock of that.”
The monarch went on to welcome Lord Cameron to the summit as both men attended an engagement demonstrating examples of clean technology and innovations to fight climate change at the Heriot-Watt University campus.
Lord Cameron said: “I would not have missed it for the world.”
After holding a second bilateral talk with the president and vice president of Guyana, the King held a third with Sheikh Mohamed bin Zayed Al Nahyan, the president of the United Arab Emirates, with the pair then formally launching the Cop28 Business and Philanthropy Climate Forum.
As part of the trip and his discussions with world leaders, the King is also expected to promote peace in the region and worldwide.
His speech will mark the first time he has delivered the opening address at the conference as King, having previously opened Cop26 in Glasgow in 2021 and Cop21 in Paris in 2015.
His attendance comes after Liz Truss stopped him from going to the event last year despite his personal desire to attend in person.
The 2022 event was organised before the death of Elizabeth II when he was “all lined up to go” as the Prince of Wales.
However, during her brief stint as prime pinister, which covered the subsequent death of the Queen, Mrs Truss warned him against attending the conference as monarch.
His Majesty, a lifelong green campaigner, was said to have been disappointed by the decision which some reports claimed led to a row with the palace.
Palace sources were keen to highlight that the King was in Dubai at the invitation of the host nation and at the request of the UK Government.
He is attending the conference alongside both the Prime Minister and Lord Cameron and his speech was written with the “full support” of the Government.
Royal aides indicated when he ascended the throne that he would continue to champion the environment, a passion he has pursued for more than five decades.