scenario and by a further 80 percent to offset the projected stresses arising from climate change (Figure 1). Yet the model indicates that if population remained constant at the 2005 level, agricultural productivity would need to rise only 25% under the ‘business as usual’ scenario ─ i.e., more of the required productivity increase under the ‘business as usual’ scenario is necessitated by population growth, than by increases in consumption per capita.

The developed world’s carbon emissions per capita are far higher than those of the developing world, but the latter accounts for nearly all the projected increase in emissions between now and 2050 (Stern 2006:Figure 7.3). While emission rates in the developed world seem to have peaked, they are growing rapidly in the developing world due to both economic growth as well as population growth. Though China has had the steepest growth in carbon emissions with its high rate of economic growth, its estimated total emissions in 2008 were similar to that of other developing countries as a group (excluding India),<sup>3</sup> partly because the latter had twice the population of China (UN 2013). GDP per capita is rising rapidly across much of the developing world − including in sub-Saharan Africa in the 2000s (IMF 2010a, 2011). And nearly all the projected global population growth will take place in the developing world – whose population (excluding China and India) is projected to grow 2.7-fold between 2000 and 2100, driven largely by the six-fold increase projected for sub-Saharan Africa (UN 2013, medium variant). It is estimated that the effect of a 40% reduction in CO2 emissions per capita in developed countries between 2000 and 2050 would be entirely offset by the increase in emissions attributable to expected population growth in poorer countries over this period, even assuming no change in emissions per capita in these countries (Dyson 2005).<sup>4</sup> Managing global warming may require different policy approaches in different settings. Imposing a carbon tax is strongly recommended as the simplest way to reduce carbon emissions (Stern 2006, Nordhaus 2008, 2012). By putting a price on carbon emissions, such a tax creates incentives to conserve global common property resources, while providing incentives and fiscal resources for developing cleaner technologies. However, some major polluters in the developed world have shown limited political appetite for this, while developing countries argue that this will constrain their economic growth with restrictions which the developed world did not have to face.

For countries which still have high levels of fertility – which typically are still poor and have very low per capita emission rates, the key approach seems to be to reduce fertility. Clearly they do not owe it to the world to reduce fertility to help slow the pace of climate change. Yet they have strong reasons of their own to reduce fertility, as discussed below.

# **2.   The Unequal Impact of Climate Change**

The developed world is responsible for much of the accumulation of emissions making for climate change, since they began rapid industrialization by the end of the nineteenth century. But in a twist of fate, the impact of climate change will be felt most sharply in much of the developing world, and the poorest are the most vulnerable to any shocks. Many of these countries are short of the financial resources for adaptation/mitigation efforts, and for some the capacity to act may also be hindered by poor governance (WDR 2008:245).

<mark>“The impacts of climate change are not evenly distributed - the poorest countries and people will suffer earliest and most....First, developing regions are at a geographic disadvantage: they are</mark> 5