Figures show that, during the course of a year, cars in the UK emit 69.9 million tonnes of CO2, whereas domestic and international flights from the UK emit 37.5 million tonnes. Even though emissions of CO2 at high altitude can be more environmentally damaging than at ground level, cars still make a greater contribution to climate change than do planes. However, the number of people who think that flying is the bigger contributor has risen rapidly in the past eighteen months, a period during which there has been an increase in activity by pressure groups opposed to any growth in air travel. In a National Statistics survey 34 % of those questioned thought that cars contributed more than planes to climate change, while 40 % thought planes contributed more than cars. 47 % thought that air travel should be limited, but only 15 % were willing to fly less often.