basic human needs of food and shelter, and reducing use of traditional biomass for energy purposes, with attendant benefits in terms of slower deforestation. Similarly, the rise in the number of mobile telephone service users across the globe from 800 000 in 2004 to over 5 billion in 2020 (see the chapter by Bohlin, Forge and Blackman) holds out the promise of greatly enhanced access to communications and vastly improved mobility for millions of people. This could also have major overall economic benefits, by raising productivity and accelerating the diffusion of knowledge. INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 1. A CROSS-SECTORAL PERSPECTIVE ON THE DEVELOPMENT OF GLOBAL INFRASTRUCTURES TO 2030 2. Driving forces, trends and uncertainties affecting the longer-term outlook for infrastructure investment A whole host of factors driving the development of infrastructures need to be taken into account in any forward-looking analysis of long-term investment requirements. The core assumptions underlying almost all projections of this kind concern economic growth (GDP) and population. But other driving forces may also affect the projections, thereby constituting an important source of uncertainty. While in shorter-term projections some of these drivers may be assumed away as playing only a minor role, they cannot be ignored realistically when a longer-term time frame is considered, as is the case here. Even if only a qualitative and highly tentative exploration of their impact can be made, it is important to do so for policy purposes. This helps policy makers better understand the risks involved in the projections and the consequences this may have for policy. The authors of the sectoral chapters in this volume have explored a range of drivers and uncertainties from a variety of perspectives. Geopolitics All the authors acknowledge explicitly or implicitly the role played by geopolitical factors and their interaction with infrastructure development (though 