Some of the environmental impact comes from piles of brochures that might not get recycled, the food that gets wasted and the marketing swag that can end up in landfills. But the vast majority of carbon emissions come from air travel. “We must get ahead of change and public perception,” Jason Geall, vice president for Northern Europe at American Express Global Business Travel, said in a speech to business travel and meetings executives in London last Monday. “A failure to act now could leave us vulnerable to existential threats, such as flight caps and increased taxation and regulation.”For now, environmental concerns have not hit events companies. The GSMA, the mobile industry lobby group that hosts the conference, calculates and offsets any emissions remaining, including from travel.