I have been working on climate change and food security in several countries over the last year or two, but will write here about Mexico and Ghana. In these cases - and all the others - farmers are having to adapt to climate change on top of other changes going on anyway.
(1) The most important of these is rising population densities, leading to shortened fallows and an enforced move along the land-use intensification continuum in response to the resulting declining soil fertility. Higher proportions of income than before are having to be spent on fertiliser and weed/pest control.
(2) Secondly, in rural Mexico (Yucatan) and rural northern Ghana (Mole), the schooling of children in primary and secondary school and the frequently resulting exodus of young people to look for urban employment rather than returning to their parents' farms has resulted in a permanent loss of labour on the farm. This may be no bad thing in the long run, but in the short run it makes risk-spreading (for instance raising cattle and other animals as well as growing crops) almost out of the question in labour terms.
These two changes are forcing profound changes in farming systems in their own right, even before taking climate change into account as well.
Farmers in Ghana told us that, from the mid 1990s, they began to notice the increased unpredictability that is their main experience of climate change. Indicators for the imminent onset of the rains which used to be relied on as a trigger to planting - the appearance of certain birds and flowers, for instance - no longer meant what they had meant before. It was impossible to be sure that rains would start, or that if they started they would continue.
Their needs include quick-maturing crop varieties, which are relatively hardy. Because they are having to abandon many previous crops and crop varieties they need a lot of advice about how to innovate. But agricultural extension services no longer exist.
In Yucatan, farmers are narrowing the range of crops they grow and often investing more in livestock as adaptations both to points (1) and (2) above, and to the much more violent intensity of heat, drought and hurricanes that is their experience of climate change.
In both these places - and others worked in - the complementarity of wild foods from the forest is very important, and these foods may at times mitigate the climate change experience.
In Ghana, more commitment to rural extension is needed all round from the government agencies responsbile for agriculture, livestock and forests.
In richer Mexico, these agencies do work in rural areas, but they do not sufficiently work with one another. Villagers complained that they were offered completely contradictory advice by Agriculture and by Forests, and wished that higher level policy makers would sort out their differences, and make themselves more fully aware of local people's needs and constraints.
Dr. Gill Shepherd