Seven cities in the San Diego region signed on to the Mayors Climate Protection Agreement, but some didn’t do much more than sign it.

I imagine it wouldn’t be difficult to find other MCPA participants for whom signing was little more than an empty gesture. That should come as no surprise: it’s a voluntary treaty with no mechanism for enforcement or even monitoring, asking politically difficult feats of more than 750 mayors. One should have realistic expectations.

The promise of the MCPA has never been that all 750 mayors will muster the ingenuity and sheer cussedness to crank the city bureaucracy into motion and make the cuts. The promise is that some will. People in the U.S. need to see success stories on a relatable scale. Every city that really does put in the LED traffic lights or capture methane from its landfill or build new downtown rail transit — and profits from it — makes the case that much stronger for the next mayor. The stuff needs to go viral.