The headline says it all: “PacifiCorp labels coal a no-go for new plants.”

PacifiCorp has backed away from plans to build any new coal plants within the next 10 years, conceding that coal no longer can overcome tightening regulations and environmental opposition.

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This seems like a big deal, since — in my opinion at least — the gravest long-term climate threat from our part of the world is coal-fired power. Nationwide, coal power plants represent America’s largest source of greenhouse-gas emissions; and there’s still an awful lot of coal in the ground in the American West. Until recently, coal’s abundance, coupled with rising demand for electricity, has made a rapid proliferation of coal power seem more or less inevitable.

But this announcement throws that into a cocked hat. Perhaps the lesson here is that the politics of climate change are changing so quickly that what seemed inevitable as recently a few years ago is starting to look unthinkable.

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