You might assume that Chicago dislikes environmentalists, judging by the response they get along Michigan Avenue. They loiter on its crowded sidewalks, trying to stop people with the brightness of their T-shirts, the authority of their clipboards and the innocence of their question: “Do you have a minute to save the earth?”

Almost no passerby has that minute, let alone $20 to donate to the cause. What most people have is a scowl, a dismissive wave of the hand and the accelerating stride of a running back. In a city synonymous with Al Capone, do-gooder appeals are about as practical as a citizen’s arrest. But although 2.8 million residents of Chicago may scoff at the notion that noble intentions can stop climate change, that doesn’t mean they think the problem can’t be solved. The city’s leaders know that to get people to save the earth, you must appeal to their bank accounts, not just their consciences. And those leaders are putting their reputation on the line to prove it.

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