At 2 degrees, the Intergovernmental Panel on Climate Change warned, the pressure on cities could grow tremendously: 37 percent of the world’s population would be exposed to the kind of severe heat that afflicted Southeastern Europe in 2007, and 411 million would face water scarcity, like this year’s drinking water crisis in Cape Town.

Urban “heat island” effects could amplify the problems and increase the likelihood of disease, bringing migrations of climate refugees and further straining infrastructure.

Within the United States, the recently released Fourth National Climate Assessment suggests big problems for urban areas, with the incidence of daily tidal flooding “accelerating in more than 25 Atlantic and Gulf Coast cities” thanks to sea level rise; that flooding has increased from five- to tenfold since the 1960s in many coastal cities. The other effects of climate change, including the ways it boosts droughts, floods and wildfires, would put more pressure on cities to adapt, mitigate the effects of climate change and become resilient.

At the conference in New Orleans, Judge Emmett took part in a panel with Carmen Yulín Cruz, the mayor of San Juan, Puerto Rico, and LaToya Cantrell, the mayor of New Orleans. The leaders agree that you can’t fight nature in terms of the disasters that have hit their homes, but you can learn to accommodate it — or, at least “Stay out of nature’s way,” as Judge Emmett says, and prevent building in areas that tend to flood.

Ms. Cantrell stressed the importance of understanding the complexity of the problem. “You have to look at storm water management as a system,” she said. “You can’t pump your way out of it; it’s not just pumps and power.” Instead, preparing for disasters and recovering from weather challenges require many different strategies, including “holding that rainwater, keeping the flow from going into the drains faster, raising your homes above the flood line.”