The most widely used global population projection of the UN is the “medium” variant. But in fact, the UN develops several different scenarios which point to the possibility of very different population outcomes over the period under consideration here. For example, under the “low” variant of the UN’s 2010 projections, the global population would, in fact, peak just before 2030 and start declining thereafter. The “high” variant, on the other hand, would see a very considerable increase in the global population over the coming decades (Figure 2.1).