Mr. Bloomberg owns a helicopter and two jets, both Falcon 900s. He flies everywhere on private jets, by far the least efficient form of transportation on or above the earth. He takes his jet to Bermuda many weekends. He has flown around the globe on it. He uses it to go to Washington. He is planning to get to Copenhagen for the climate conference by private jet, too.

The carbon math works out like this: by taking his Falcon 900 to Denmark, Mr. Bloomberg will be responsible for the release of 37 times the carbon dioxide than if he and his entourage flew on a scheduled commercial flight. The calculations were done at my request by Dimitri Simos, the developer of software used by the airline industry to assess aircraft emission and performance. Mr. Simos said that a Falcon 900 carrying eight people from Newark to Copenhagen would produce 21.6 tons of carbon dioxide. By adding eight people to the scheduled Scandinavian Airlines flight, the aircraft, usually an Airbus A330-300, would produce an additional 0.58 tons of carbon dioxide.

Mr. Bloomberg’s routine trips to Bermuda are even more carbon costly: the private jet produces 130 times more emissions than going commercial. On those jaunts, Mr. Simos said, the Falcon produces 4.3 tons of carbon dioxide; putting another two people on an American Airlines Boeing 757-200 that flies to Bermuda would produce only 66 more pounds.

This is not Bloombergian hypocrisy; it is a paradox, shared by most of humankind. I’ve lived within a block or two of a subway station since birth, yet owned a car since I got a driver’s license. There is a long list of public figures  from movie stars to politicians to journalists  who preach conservation for everyone else, while living in mega-homes and flying in Gulfstreams. It is probably not a good idea for the rest of us to look down our noses at people who cannot resist such temptations until we can afford them ourselves.

In the case of Mr. Bloomberg, his addiction to private jets is striking because in so many other parts of his life, he appears fastidious about shared resources. The lighting and electronic gear in his family foundation building use 20 percent less energy than typical offices; the foundation recycles rainwater to irrigate a green roof; even most of the construction and demolition debris were recycled.