"Another unanticipated possibility would be a nickel rich eruption in which bacteria that converts nickel to methane would then deliver the final blow to a run away climate catastrophe."

Dunno about him and his poetry, but the above is total bollix. Nickel is a metallic element with one kind of atom. Ni. Methane is a molecular gas made of nothing but carbon and hydrogen atoms. C and H.   Not exactly interchangeable, huh, even by very very very clever bacteria.