Terra Eco said it performed the study on these leaders because they were defenders of ecological causes. “A bit of transparency about the carbon generated by our elected officials” was due, the magazine’s editors said.

What is perhaps most surprising about the findings is how some of the leaders traveled more ecologically than others. Mr. Sarkozy, for example, produced a smaller carbon footprint than his British and German counterparts but still voyaged over 200,000 miles – more than twice as many as Mr. Brown and nearly twice as many as Ms. Merkel.

The reason, according to Terra Eco, is largely due to the types of aircraft used by the leaders. Although the authors of the study readily admit that determining the types of aircraft used for all trips was difficult, they concluded that Mr. Brown deserves the title of “the least green” in part because of his heavy reliance on Boeing 747, 757 and 777 aircraft.

Terra Eco says Mr. Sarkozy, meanwhile, kept a cap on his emissions by using an Airbus A319 converted for VIP use. But the magazine warns that the president could be poised to broaden his footprint considerably. It says the French state has confirmed the purchase a larger Airbus A330 for the president that is more polluting.