Friends of the Earth UK is urging vacationers to travel closer to home and to take trains rather than planes. A planeload of passengers flying from Britain to Florida and back produces as much carbon dioxide as does the average British driver in one year. The world’s 16,000 jet airplanes pump out more than 600 million tons of carbon dioxide annually, contributing significantly to the problem of global warming, and the number of people flying is expected to double in the next 15 years. “It’s not that car travel is particularly fuel-efficient. It’s just that flying burns up so much fuel and pollutes even more,” says Simon McRae of Friends of the Earth.