Michael Copeland’s terrific panel at FORTUNE Brainstorm: Tech offered attendees a look at the ways cities are addressing pressing problems cities face: traffic, pollution, overcrowding, clean water, etc. The panelists — Clinton Climate Initiative chairman Ira Magaziner, Cisco CTO Padmasree Warrior, Sun’s Greg Papadopolous and Hara CEO Amit Chatterjee — seemed to agree that there are so many solutions cities can implement without getting the buy in of citizens and corporations. (Fixing pipes in Paris, for example, to reduce water waste.)

But what happens after you address the low-hanging fruit? Chatterjee offers his thoughts on how corporations should think about their business models when society starts to require reduction of carbon emissions.