Charles, the heir to the throne, said the planet was facing an existential crisis as he urged the Commonwealth to take forward its ideas to COP23, the next United Nations climate summit in the German city of Bonn in November.
While the 52-member Commonwealth contains G20 industrial powers like Britain, Canada and Australia and emerging forces like India and Nigeria, many of its members are developing island microstates.
The 2015 COP21 Paris accord targets keeping the rise in temperatures within two degrees Celsius (3.6 Fahrenheit) above pre-industrial levels and strives for 1.5 C (2.7 F) if possible.
"For some countries, particularly, the small island developing states of the Commonwealth, the difference could scarcely be more critical as it may literally mean the survival of their countries or their extinction," he told ambassadors and science experts gathered at the organisation's London headquarters.
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"We face an existential crisis in every sense of the word."
A two-day Commonwealth conference in October brought together global experts to thrash out innovative schemes that could pull carbon out of the air and put it back into the Earth.
Today's gathering brought together the results of that conference and try and forge a common approach to COP23.
"The ideas we need are already out there but they will not happen by chance."
The Commonwealth is looking at notions including carbon- absorbing concrete and getting more productive agriculture through mimicking the ecosystems of wild, untended land.