The G7 group will promise to move away from coal plants, unless they have technology to capture carbon emissions.
It comes as Sir David Attenborough warned that humans could be “on the verge of destabilising the entire planet”.
He said G7 leaders face the most important decisions in human history.
The coal announcement came from the White House, which says it is the first time the leaders of wealthy nations have committed to keeping the projected global temperature rise to 1.5C.
That requires a range of urgent policies, chief among them being phasing out coal burning unless it includes carbon capture technology.
Coal is the world’s dirtiest major fuel and ending its use is seen as a major step by environmentalists, but they also want guarantees rich countries will deliver on previous promises to help poorer countries cope with climate change.
The G7 will end the funding of new coal generation in developing countries and offer up to £2billion for poorer nations to stop using the fuel.