By 2025, between 10 and 15 nations will be added to this category. Between 1990 and 2025 the number of people living in countries in which renewable water is a scarce resource will rise from 131 million to somewhere between 817 million under the UN's low projection of population growth and 1.079 billion under the high projection. For several countries varying population scenarios could mark the difference between potentially manageable water stress and outright water scarcity in 2025. In 1990 Peru, for example, had 1,856 cubic meters of renewable water per person per year. Under almost any conditions, that figure will plunge, but the rate of population growth could determine whether Peru crosses into water scarcity or hovers in water stress with nearly 1,200 cubic meters per person in 2025.
Similar possibilities face Tanzania, Zimbabwe and Cyprus.
For Sri Lanka, Mozambique and Mauritania, the population trajectory will determine whether the threshold is crossed from relative water abundance to stress. Zimbabwe, Tanzania and Peru can will avoid falling below 1,000 cubic meters per capita only if they follow the UN low projection. By 2025, India's population is expected to exceed 1.4 billion under the UN's medium projection, and the chronic water scarcity that already plagues many regions of the country is all but certain to intensify. In that year, according to the medium scenario, each of China's projected 1.5 billion citizens will have 1,818 cubic meters available. In the North China Plain, however, water shortages are already acute, and demand is expected to outstrip supply by the turn of the century.