Naked Capitalism has the article Fed Official: Climate Change is an ‘International Market Failure’.

Since Congress has yet to take sufficient action, Rudebusch says that the Fed could, in theory, take matters into its own hands by encouraging a shift away from fossil fuels. The problem is, the Fed’s only official job is to keep inflation tame and unemployment low. And its tools are limited to buying and selling government debt to tweak interest rates.

What was the Fed buying in the various phases of quantitative easing? Quantitative Easing Explained.

The bank buys securities from its member banks to add liquidity to capital markets.

So, there already seems to be a little stretchiness in the definition of what the Fed can buy. Still, the stretchiness that already exists might not be enough to cover what Rudebusch thinks is necessary.