The diversity which we have within crops – all the different kinds of wheat, rice, etc. – is a genetic resource which stands between us and starvation on a catastrophic scale we cannot imagine, according to Cary Fowler in a TED talk given in July. Crop diversity is the biological foundation of agriculture, and that foundation has been crumbling, with a mass extinction of varieties now occurring. In the 1800s in the US, farmers were growing 7100 named varieties of apples, of which 6800 are now extinct.
Why do we not just save the “best one” of each type of crop, rather than trying to save all of them? There is no such thing as a best one; today’s best variety may be vulnerable tomorrow to an insect or disease. Also, a variety which is not economical now may possess some quality that others do not, that will make it useful in the context of climate change. We need to be saving different varieties as raw materials which we can use in the future.
Diversity gives up options, and we need options to adapt to climate change. In many countries the coldest growing seasons are going to be hotter than the hottest of the growing seasons in the past. Climate change is going to be worst in south Asia and sub-Saharan Africa. Anticipated climate change in South Africa over the next 20 years will result in a 30% reduction in crop yields for current maize varieties. We have to get climate-ready crops into the fields quickly.