Many African countries are classified as arid or semi-arid, and climate change is likely to reduce the length of the growing season in these regions. Projected reductions of yields could be as much as 50 per cent by 2020 in some countries (IPCC 2007, Chapter 9). The small-scale low-income farmers will probably be the most affected. This effect on agriculture would result both in lower economic growth and in lower food security.