Prince Charles and Camilla watched a traditional kendo sword performance
Prince Charles has warned that the financial crisis should not distract from the longer-term problem of the "climate crunch".
Speaking during a visit to Tokyo, the Prince of Wales said the global economy was "rightly a preoccupation of vast significance and importance".
"But we take our eye off the climate crunch at our peril," he added.
Prince Charles, along with his wife, the Duchess of Cornwall, is visiting Japan for the first time since 1970.
Their arrival was timed to coincide with the 150th anniversary of the establishment of diplomatic relations between Japan and Britain.
The trip is part of a wider tour of the Far East, which will also see the prince and the duchess travel to Brunei. Charles will later journey on to Indonesia alone.
The prince spoke on Tuesday after viewing exhibits related to global warming at Japan's National Museum of Emerging Science and Innovation.
He told an audience of businessmen and government officials: "It is not an exaggeration to say that we face the biggest challenge our planet has ever seen, literally a battle for survival.
"Given the current turbulence in the international financial system and the immediate and damaging effect it is having on the whole world, the credit crunch is rightly a preoccupation of vast significance and importance.
"But we take our eye off the climate crunch at our peril.
"While we hope and pray that the underlying strengths of the global economy will once again enable it to bounce back, the effects of climate change will be far, far from temporary and will indeed be irreversible."
Charles called on developed nations to cut carbon emissions by 70% to 80% by the year 2050, saying any crisis faced today would be nothing compared with what would befall the world "if we continue on a business-as-usual basis".
"The scientists tell us there is just the smallest window left for us to make the transformational changes in the way we live needed to stop catastrophic climate change," he said.
The visit celebrates 150 years of diplomatic relations with Japan
"The worry of course is that this window of opportunity is available to us at exactly the same time as the global economy is under severe strain. But despite this we simply mustn't abandon the drive towards a low carbon economy."
Charles and Camilla were greeted at the museum by dozens of Japanese schoolchildren waving British flags.
Earlier, they watched a traditional kendo performance at Tokyo's Keio University and later they were expected to visit a solar panel lab, meet ecology students and tour a sustainable forest site.
The prince has increasingly championed an environmental cause and has made efforts to reduce his personal carbon emissions.
His 38-year-old Aston Martin now runs on bioethanol from surplus wine, while his fleet of Jaguars, Audi and Range Rover use biodiesel made from recycled cooking oil.