As world leaders met in New York, one question kept coming up at climate change events: How did you get here?
Swedish teenage activist Greta Thunberg made headlines for deciding to sail rather than fly to New York for the climate summit that kicked off the United Nations' key annual meeting.
But world leaders and delegates arrived by plane in their thousands, prompting a gathering of tourism executives in New York to ponder how to address the fact that flying adds to the greenhouse gas emissions responsible for global warming.