Speaking at a conference for scientists at St James’ Palace in London, Prince Charles said by ignoring climate change we were turning the earth into a ‘dying patient,’ and called for urgent action.

He said: “If we see our forests and the planet as our patient, the risk of delay is so enormous that we cannot wait until we are absolutely sure the patient is dying. That is a monumental risk no doctor would ever take.

“The Earth’s physical, chemical and biological systems are crying out to be treated – now.”

Owen Paterson, the Conservative Secretary of State for the Environment, and Lord Stern were among the audience for the two day conference about Tropical Forest Science.

Prince Charles said tropical forests play a “critical role” in the environment, by providing food, water and energy as well as a habitat for animals and plants. He told delegates there needed to be more understanding about deforestation so that the world’s forests were appreciated and rates of deforestation slowed down before it was too late.

He added: “The continuing nightmare I have consists of moving from the ghastly sound of my own voice to the sound of a perpetual scientific experiment which only finally produces the evidence and proof once everything is gone and we have tested and monitored it all to destruction.”

He cited examples across the globe where forests are being protected, such as work in Brazil to limit deforestation in the Amazon and in Costa Rica where the forests have been expanded, adding that in his lifetime “perhaps half of the world’s tropical forests have already disappeared.”

The Prince of Wales has been outspoken about environmental issues in the past, having called for donations for farmers following 18 months of bad weather and setting up the Countryside Fund. He has previously warned about the importance of protecting rural areas from insensitive developments and the need to safeguard village life to ensure the rural landscape remains, as well as spoken out against genetically modified crops.