Attendees at the World Economic Forum in Davos last week repeatedly heard that the path to a carbon-free future runs through the financial system. “Banks, insurers and pension funds are as culpable for the climate emergency as the fossil-fuel industry,” Greenpeace charged. “Immediately and completely divest from fossil fuels,” Swedish teenager and climate activist Greta Thunberg demanded.

And indeed, environmentally conscientious bankers and investors are rushing to get on the right side of history by shunning coal, Canadian...