Climate change will force farmers to reorganize what is grown where
For a behind-the-scenes look at our data journalism, sign up to Off the Charts, our weekly subscription-only newsletter.
Aagricultural produce has been rising for decades, defying predictions that the world’s population would exceed its food supply. Such benefits come largely from scientific advances in areas such as fertilization and genetics. The speed of this discovery may slow down. Even so, farmers could still increase yields by changing a low-tech part of their work: picking what to plant where.
A surprisingly large proportion of farmland is used for crops that do not add nutritional or economic value. One study in Natural geology It showed that by changing what is planted on existing fields, yields could increase enough to feed 825m more people, and reduce water use by 10%. And global warming is likely to make current crop rotation even more efficient: paper in Nature’s Food found that climate change could cut maize yields by 6-24% by the end of the 21st century.
Today, cropland imbalances tend to be worse in poor countries. Of the 12 crops studied in a recent study in the Proceedings of the Royal Society, cassava, rice, sorghum and potatoes were the most frequently planted in unsuitable places. The first three are preferred by smallholder and subsistence farmers. Since such producers have to feed their families every year, they often prioritize resistance to bad weather rather than maximizing the yield.
There is no practical way to get millions of small farmers to change their crops. But global warming could force even agricultural companies, which do much of the farming in richer countries, to change what they plant. Maize, America’s largest crop, is sensitive to heat, and may need genetic modification to survive even under moderate warming conditions. Soyabeans, grown on nearly half of Brazil’s farmland, are also expected to suffer. And coffee struggles with extreme temperatures, which make climate change more common. In contrast, breadfruit, which can survive for months without water, should do well at low latitudes. But breadfruit harvests won’t do much for caffeine-starved office workers.
Warming also brings opportunities. Parts of Russia, Canada, China and the northwestern United States should be prime areas for wheat, which withstands heat and drought better than corn – although deforestation in those regions will accelerate change climate Some hotter and poorer areas could also benefit: more rain could improve rice production in India and West Africa.
Although these projections represent the best estimates of how climate change will affect individual crops in specific regions, they are highly uncertain. Rather than preparing for one situation, the best defense for farmers is to learn about a wide variety of crops. The only guarantee is that global warming will change agriculture in unpredictable ways.■
For more coverage of climate change, sign up for Climate Matters, our subscription-only fortnightly newsletter, or visit our climate change hub.
Chart sources: “Climate analogues suggest limited potential for intensification of production on current cropland under climate change”, by TAM Pugh et al., Nature Communications, 2016; The Economist