As terrible as many things in the world are, climate is unique in posing an existential threat to civilization. And it’s horrifying that so many political figures are dead set against any serious action to address that threat. Despite that, there’s still a chance that we’ll do enough to avoid catastrophe — not because we’ve grown wiser but because we’ve been lucky. We used to believe that achieving big reductions in greenhouse gas emissions would be difficult and expensive, although not nearly as costly as anti-environmentalists claimed. Over the past dozen years or so, however, we’ve experienced a technological miracle. As nicely documented in an article by Max Roser, the costs of solar and wind power, once dismissed as foolish hippie fantasies, have plunged to the point that quite modest incentives could lead to a rapid reduction in use of fossil fuels. But was it really luck? Did this miracle — actually two miracles, since generating electricity from the sun and from the wind involve completely different technologies — just happen to arrive in our moment of need? Or was it a consequence of good policy decisions?

The answer is that there’s a pretty good case that policy — the Obama administration’s investments in green energy and European subsidies, especially for offshore wind — played a central role.