As he wrapped up a six-day trip to New Zealand ahead of three days in the Solomon Islands, Charles said the need for climate action was urgent.
"We have reached a tipping point and we still have the ability to change course, but only 10 years," said the first in line to the British throne, who has been a passionate environmentalist for decades.
He said climate change was a scientific fact, rejecting suggestions from sceptics that "scaremongering" was dominating the debate.
"Nothing is sacred anymore, we are reaping a loss of biodiversity and experiencing the impacts of climate changes. We urgently need to pay the mounting debt."
He and wife Camilla, Duchess of Cornwall, will have the chance to see the impact of climate change at close quarters when they make their first visit to the Solomon Islands on Saturday.
Some communities in the impoverished archipelago have already had to move because of rising seas and the entire population of about 660,000 has been affected by increasingly extreme weather, including wild cyclones.