Marty Chavez bought his daughter a prom dress at Barney’s — “on sale!” Clover Moore picked up a couple of cool T-shirts at the Guggenheim. Rocky Anderson debated skipping the luncheon speech to get a pastrami sandwich with a pickle — “a big one.”

So it goes when the mayors of some of the biggest — or at least most progressive — cities in the world meet to discuss global warming.

Mr. Chavez is the mayor of Albuquerque. Ms. Moore is Lord Mayor of Sydney. Mr. Anderson has the distinction of being not only the mayor of Salt Lake City, but also co-sponsor with Robert Redford of the Sundance Summit on climate change. He’s the guy who was pining for a pickle.

Along with several dozen mayors from Chicago to Shanghai, they were here for the C40 Large Cities Climate Summit hosted by Mayor Bloomberg at the Essex Hotel. It certainly looked like they were doing exactly what they were supposed to do: stealing.

“Mayors are quick to steal any good idea we find,” Mayor Chavez of Albuquerque said. For instance, “From Salt Lake City, we stole methane recapture. And we have a rapid bus [system] based on Curitiba.” He nodded at the mayor of Brazil’s Curitiba, Carlos Richa, who was waiting for an elevator.

So, great. All the mayors get together and exchange best practices and our environment is the better for it. But mayors aren’t only the stewards of our future. They’re also … conventioneers. Like dentists in town for a conference on plaque, they listen, learn, shop — and gossip.

After discussing his city’s award for water conservation, for instance (and pointing out that New York probably loses a third of its water underground, due to leaky pipes), Mr. Chavez went on to chat about his drinks at the Carlisle. “I was shocked by the prices,” he said.

On the other hand, he was very pleased with the dress he got his daughter at Barney’s and the tie he bought at Bloomingdale’s — a tie he was wearing to lunch when he found himself seated next to the mayor of Rome.

Ooh — the Italian mayor’s suit put his to shame, right?

“You know what? No,” Mr. Chavez said proudly. “The Brazilian mayors” — they’re the ones looking really sharp.

Lord Mayor Moore of Sydney was looking really sharp herself, in a big, red, beaded choker. What particularly impressed her about New York, however, was not the style: “I love the dogs,” she said.

In Sydney, many of the parks don’t allow dogs, something she is passionately trying to change.

Another Australian mayor, John So of Melbourne, had a New York dog moment of his own. He’d brought along his daughter, who got up the guts to buy a hot dog from a cart. “She told me it’s very good,” he said.

He’s now thinking of trying one himself.

Maybe he’ll end up as high on New York meat as Salt Lake City’s Rocky Anderson. After admonishing our city for its lack of streetside recycling bins, Mr. Anderson conceded that our pastrami beats Utah’s. (Like that’s so hard.)

Mayor Will Wynn of Austin was far more loyal to his town. Informed that Essex House is just down the street from Whole Foods, an Austin-born institution, Mr. Wynn said, “I live next door to a Whole Foods.” Shops there three times a week. “They have these Susie’s Southwestern Eggrolls and they are so good dipped in salsa,” he said.

With any luck, he follows the mayor of Toronto’s lead and separates his food waste from his other trash, to make for more efficient recycling. “You can put your dog waste and Kleenex and diapers in, too,” Mayor David Miller said, digging into his sandwich.

Business and pleasure. Solid waste and Barney’s. Methane and pastrami. Mayors are people, too. Let’s hope they save the world in between bites.