Prince William plans to participate in the United Nations climate conference in South America next month, as confirmed by palace sources.
The father and son duo appeared together on Thursday evening at a reception leading up to the climate summit, which is planned for in the Amazonian city of Belem.
Father and son were present at the museum gathering, marking an rare public appearance together at a environmental conference preliminary meeting arranged together with the UK government.
King Charles has been a long-time champion of environmental conservation - and Prince William has inherited the mission, with his own environmental prize initiative, which will be taking place in South America ahead of the COP summit.
Official representatives have described William's involvement at the next COP as stepping up an important role in "environmental negotiations".
The monarch and his heir, arriving together in the royal vehicle, were welcomed attendees such as conservation experts, researchers, environmental activists, foreign representatives and government officials.
This involvement involved presentations in concert with President Emmanuel Macron of the French Republic and other global statesmen at the Ocean Finance Summit in Monaco during the current year.
The climate conference will coincide with the prince's own climate innovation prizes, which will conclude in Rio de Janeiro the day before he attends the COP summit on 6 November.
Recently the prince described the prize competitors as "heroes of our time".
The monarch has been a prominent presence at previous climate summits, delivering the inaugural speech in Dubai for COP28, including the observation: "Our responsibility is to protect the world we inhabit".
"Throughout my life I've dedicated a substantial portion of my life trying to warn of the survival risks challenging our world over climate change, environmental shifts and ecological decline," the sovereign addressed attendees.