Critics of the Government's policy advocate addressing climate change impacts by constraining demand for air travel. The study Predict and Decide - Aviation, climate change and UK policy concludes that the Government should seek an alternative aviation policy based on managing demand rather than providing for it.[48] This would be accomplished via a strategy that presumes "… against the expansion of UK airport capacity" and restrains demand by the use of economic instruments to price air travel less attractively.[40] Other studies point to a significant contribution to aviation's climate change emissions by the social phenomenon hypermobility, and the increasing prevalence of hypermobility among UK and global citizens.[49] and Mander & Randles (2009).[50] Key to the concerns expressed in these studies are: that that vast distances are easily travelled in a relatively short time, entailing substantial greenhouse gas emissions; that these emissions are made at-altitude where they have much greater climate consequences than emissions made at ground-level; and that social pressures[51] and marketing programs such as frequent flyer miles programs that both encourage a growing amount of travel and means to go.