I challenged our friend Andy Jarvis to summarize his just-out paper (with assorted co-authors) in Nature Climate Change ((Rippke, U., Ramirez-Villegas, J., Jarvis, A., Vermeulen, S., Parker, L., Mer, F., Diekkrüger, B., Challinor, A., & Howden, M. (2016). Timescales of transformational climate change adaptation in sub-Saharan African agriculture Nature Climate Change DOI: 10.1038/nclimate2947)) in a tweet, and this is what he came up with:
@AgroBioDiverse Model maps where + when farmer must change staple crop: beans, banana + maize hit most; sorghum, millet + cassava to rescue.
— Andy Jarvis (@ajarviscali) March 7, 2016
Not bad, but let’s unpack it a bit. Andy and his colleagues ran climate models for sub-Saharan Africa and looked at what would happen over the course of this century to the areas where different crops are currently being grown. Crucially, they tried to figure out when it would become untenable to continue growing a given crop in a given spot, thus triggering a switch to another crop altogether. Absent, that is, some kind of adaptation, such as bringing in varieties better suited to the new conditions, or altering agronomic practices.
As Andy says in his tweet, beans, banana and maize are the worst hit: farmers in 60% of the current African bean area, and about 30% of that of the other crops, will need to think about some other crop at some time during the 21st century. That hits home, as people who follow this blog will know that my mother-in-law’s farm is in maize-and-beans country. Well, fortunately, the highlands of central Kenya do not seem, in this analysis, to be too badly impacted. But what are the descendants of my mother-in-law’s equivalents in the dryer parts of East Africa, and in southern Africa, to do?
…farmers in the maize-mixed farming system might, in the long run, shift to more drought-tolerant cereals such as millet and sorghum, which we identify as viable substitutes in many locations, although these may experience yield reductions.
Alas, there’s more:
…in some areas in the southern Sahel and in dry parts of Southern and Eastern Africa even these drought-resilient crops might become increasingly marginal. For these areas, a more drastic transformation to livestock might be necessary, because cropping might not be a viable livelihood strategy in the long run.
Scary. Better get breeding.