Climate change legislation has been dying in the Senate for months now, but Harry Reid’s decision to finally admit as much — in the midst of an endless East Coast heat wave, no less — has supporters of cap-and-trade casting about for somebody to blame. They’ve blamed the Obama administration, for prioritizing health care reform over an energy bill. They’ve blamed the American people, for being too concerned with economic issues to grapple with longer-term threats. And they’ve blamed figures like Lindsey Graham and John McCain, erstwhile supporters of cap-and-trade who have steadily backpedaled away from it.

But most of all, they’ve blamed conservatives — for pressuring Republican lawmakers to abandon legislation they once supported, and for closing ranks against any attempt to tax and regulate our way to a lower-carbon economy.

Cap-and-trade’s backers are correct to point the finger rightward. If their bill is dead, it was the American conservative movement that ultimately killed it. Climate legislation wasn’t like health care, with Democrats voting “yes” in lockstep. There was no way to get a bill through without some support from conservative lawmakers. And in the global warming debate, there’s a seemingly unbridgeable gulf between the conservative movement and the environmentalist cause.

To understand why, it’s worth going back to the 1970s, the crucible in which modern right-wing politics was forged.