Bill de Blasio, New York City’s new mayor-elect, didn’t spend much time during the campaign talking about climate change, but he’ll likely spend a lot of his time at City Hall dealing with it.

New York finds itself these days with an unusual conundrum: Its biggest problems are largely the byproduct of its biggest successes. Just 20 years ago, New York was, like American cities generally, blighted by rampant crime and less populated than at its mid-century heyday.

Today, New York City’s central challenge is one that virtually any other city would love to have: Too many rich people want to live there. But Wall Street bankers, trust funders, and wealthy foreigners looking for a pied-à-terre have driven up the price of housing to levels that threaten to eject the creative classes that have powered New York’s renaissance. The high cost of housing is also the main reason New York’s homeless population is at an all-time high.