Both domestic and international tourist numbers have grown continuously and at a rapid pace for more than six decades, as mirrored in growth in international tourist arrivals from 25 million in 1950 to 924 million in 2008. Emissions from tourism have grown concomitantly, but more important than understanding current emissions from tourism, as presented in previous chapters, is gaining an understanding of the future growth in emissions. The following sections highlight global, national, individual, and ‘per trip’ emission trends.