How much money do you think it will cost to save the world from a climate catastrophe?

According to King Charles III, it's about $5 trillion. Every year.

That’s what the British royal told a packed conference of green advocates and state leaders on Friday who flew from all around the world – many on private jets – to meet up at the plush United Nations climate summit in Dubai, known as COP 28.

US COMMITS TO SHUTTING DOWN ITS COAL PLANTS DURING COP28

Warning that the world is "hurdling into dangerous, uncharted territory," Charles, 75, said he was praying for "transformational action" to come out of the gathering.

"How can we bring together our public, private, philanthropic and NGO [non-governmental organization] sectors ever more effectively, so that they all play their part in delivering climate action?" Charles asked the crowd, which included former Vice President Al Gore and Secretary-General of the United Nations António Guterres.

Public finance alone won’t cut it, he added. 

"But with the private sector firmly at the table… we could mobilize the trillions of dollars we need, in the order of four-and-a-half to five trillion a year, to drive the transformation we need."

To put that figure into perspective, it is about 20% of the U.S. Gross Domestic Product in 2022 which was $25.46 trillion, according to the Bureau of Economic Analysis.

Charles did not give a breakdown of who should pay what, or where exactly the money would go, although he did say that the funds should flow to projects driving sustainable changes and away from practices that "make our world more dangerous."

Part of the funds, at least, would likely be placed in the Green Climate Fund, a United Nations fund tasked with helping developing countries mitigate and combat climate change. 

On Saturday, the U.S. pledged $3 billion to the fund, on top of an additional $2 billion previously delivered by the United States. U.S. Special Envoy for Climate John Kerry announced at the summit that the United States will not build any new coal plants and will phase out existing plants to limit global warming to 1.5 Celsius.

In his speech, Charles also called on different types of organizations to come together to fight climate change and asked for the world to ramp up investment in green, renewable energy.

"Some important progress has been made, but it worries me greatly that we remain so dreadfully far off track," Charles said.

It is unclear if Charles will be donating to the fund. The Royal family is worth $28 billion, according to Forbes.