What will the future hold for the deserts of the world? Based on the foregoing analyses, we can assert with some confidence a number of simple predictions: deserts are and will remain constrained in their productive potential by their very nature - the widely varying conditions of the desert ecosystem, the scarcity of water, and the oscillating resource variability. This basic nature of deserts will not change in the forseeable future. However, global climate change, coupled with increased population pressure, particularly in the desert margins, montane areas and wetlands, is likely to affect the more productive desert areas and pose some new and significant threats to biodiversity and sensitive endemic species. By contrast, the hyper-arid cores of the desert biome - the vast wilderness of the "deep" desert - are going to be less affected by mounting pressures on their fragile biological resources. Water depletion, on the other hand, as well as salinization of irrigated agricultural soils, are likely to continue as two of the main environmental problems in many deserts, encouraged by modern technologies for groundwater prospecting and pumping. A sort of modern itinerant agriculture has already emerged, where large barren areas of salinized agricultural soils are left behind as groundwater resources become exhausted and agricultural operations move on to new lands and to new untapped aquifers.

These predictions, however, are not fixed and unchangeable. The scenario analyses discussed in the previous sections show that there is a wide range of possible outcomes for deserts, an array of alternative futures. Whether deserts will follow a path of intensive development, industrial-scale agriculture projects and mega-cities attracting massive immigration - a vision that has been called, somewhat sarcastically, the "Cadillac Desert" (Reisner 1986) - or an alternative path of sustainable development, spurred by a "sense of place" and prioritizing the desert environment and the traditional culture of local communities, will be largely determined by our common visions and collective action taken to fulfil them.

In reality, current development in many deserts seems to suffer from a lack of vision altogether. Few, if any, coordinated programs exist for either development or conservation of the land. The unique values and limitations of the desert are rarely acknowledged. Development schemes, such as programmes for irrigated agriculture or mass tourism, tend to spring up haphazardly with no attempt to coordinate them or to plan for their long-term sustainability. Immigration to the desert is often random and opportunity-driven, and new settlements sprawl over valuable landscapes and create problems for water supply and waste management. Without proper planning and a vision of sustainability, traditional lifestyles atrophy and indigenous knowledge is lost, victims of short-term, ephemeral economic projects.

So what is to be done; what vision should be pursued for the successful long-term development of deserts, especially in developing countries? Quite clearly, a continuation of the energy- and water-intensive development model will lead to even more severe water depletion and degradation than is observed today, followed by potential conflict over water resources among users, escalating costs of supply, and the continuation of a non-renewable model in which water, often under immense subsidies, is, paradoxically, used for low-value purposes. At the other extreme, increased isolationism with exclusive reliance on traditional knowledge runs the risk of losing access to new sustainable technologies and might lead to diminished opportunities for younger generations, and, eventually, to reduced livelihood and economic development options.

A new, more balanced vision is needed, where deserts and their inhabitants are valued both by governments and civil society; where sustainability and the well-being of desert people are given highest priority; where desert development is guided by a long planning horizon and based on an acute understanding of the limitations and potential of these very unique environments; where market forces are harnessed to promote a desert-compatible development, such as low-impact services or hightechnology development; where traditional livelihoods are given the opportunity to survive with dignity; and where wetlands, oases, desert mountains and other environments at risk are protected.

Decisions can and should be made not to change the desert, but to live with it and preserve its resources for the future. The active participation of community groups in each desert for the development of a common vision is a fundamental condition for the successful formulation and implementation of policies towards an environmentally sustainable future. Desert peoples can, and should, take charge of their own development, plan for risks, and adapt to changing conditions while preserving their deep connections to these remarkable landscapes. The challenge remains to harness not only local, but also global policy mechanisms and market incentives to develop a viable future for our deserts, where both the successful protection of the environment and economic development opportunities are achieved.