New York Times: Not so, according to Climate Care, a United Kingdom-based carbon-offsetting company, whose statistics show that cruise ships emit nearly twice as much carbon dioxide as airplanes. “We now know they are far more polluting per passenger kilometer than planes,” said Justin Francis, co-founder of Responsibletravel.com, a directory of environmentally friendly vacations that partners with Climate Care. “Add to that the fact that many passengers fly to the port of departure before boarding,” he …