I think he was actually looking at the picture of the mining of Bitcoin placing very huge demand on the use of fossil oil and that can rightly be said to pose some threat, but it is without a double not a significant threat to the earth and the availability of renewable alternative energy further reduces whatever burden there would have been.

If anyone is interested in knowing what financial system that's actually killing the earth, one only need to look at the ozone layer depletion caused by deforestation and falling of trees, which is still a major raw material for making paper (fiat) money - perhaps blessing us with floods and droughts, pollution, loss of soil fertility, spread of deserts,etc.