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Averting a climate-led food crisis in Africa

Local crop varieties could provide solutions to temperature rises.

African farmers could find more drought resistant crops on their doorsteps. Credit: Alamy

Most African farmers will be able to find heat-resistant crop varieties within their own borders or in other countries on the continent, providing an easy first step towards adapting to climate change, according to new research.

A study to be published in the journal Global Environmental Change1 found that by 2050, most African countries will experience temperatures they have never before encountered over at least half of their crop-growing areas. But three-quarters of these will see temperatures that currently occur in at least five other countries and so could take advantage of crops grown there.

Luigi Guarino, one of the study's authors and a senior science coordinator at the Global Crop Diversity Trust — a foundation based in Rome that aims to improve food security — says that the results will allow researchers and farmers to identify which crop varieties have the best chance of growing and surviving under future climate conditions. It also points to the crop varieties that are most important for adaptation strategies, crop breeding and conservation efforts.

"Warming is generally expected to cause reductions in rain-fed crop yields and crop suitability in Africa, so that simply shifting areas where crops are grown will be a limited adaptation strategy. Instead, adapting crops in their current locations will be critical," the study says.

Heat wave

Using historical climate-change data, the researchers calculated average temperatures over the past 40 years for the maize-growing areas across all countries in sub-Saharan Africa. They looked at maize as "it is the most important crop", says Marshall Burke, a food-security researcher at Stanford University in Palo Alto, California, and another of the study's authors.

They forecasted the rise in temperature using 18 climate-change models, then added these projections to the average historical temperatures to work out the probable temperatures in maize-growing regions in 2050.

The gene-bank collections from many areas that are likely to have the widest range of diversity are either incomplete or non-existent. Luigi Guarin , Global Crop Diversity Trust

By plotting countries' average historical maize-growing temperatures against the predicted temperatures for 2050, they could see where overlaps would occur within and between countries. The resulting graph shows that the temperatures Rwanda will experience in 2050 overlap with those experienced today in Ethiopia. Rwanda can therefore look to Ethiopia for crop varieties that might withstand the temperatures it will come across in future.

But the study found that in six countries, including Senegal, Chad and Mali, the climate will be hotter than anything farmers have experienced before anywhere in Africa.

For these countries, there is a much smaller potential pool of foreign genetic resources in which to seek crops with heat-tolerant traits, the study says. The researchers suggest that one consequence could be that farmers may no longer be able to grow maize, which is more heat sensitive than other crops. Instead, they may have to switch to sorghum and millet, which are more tolerant to heat.

Banking failures

The study then examined the extent to which maize varieties were conserved in gene banks. In particular, they looked to see if the varieties that currently grow under higher temperatures — those that will be most important for farmers as the climate warms — are well preserved. They found that countries with some of these important varieties have the poorest conservation of plant genetic resources, such as Sudan and Eritrea.

"The gene-bank collections from many areas that are likely to have the widest range of diversity are either incomplete or non-existent," says Guarino. His colleagues add that "These countries are particularly high priorities for urgent collection and conservation of maize genetic resources."

Gerald Nelson, an agricultural economist at the International Food Policy Research Institute — an independent research organization in Washington DC — says the study shows there are some "fairly easy ways to start the process of adapting to climate change". But he says that sharing information on how different crop varieties respond to temperature, and conserving and exchanging genetic material, will be vital to take advantage of the existing capacity to deal with climate change.

Emile Frison, director-general of Bioversity International, a not-for-profit research organization in Rome, says the study clearly demonstrates the interdependence of countries regarding plant genetic resources. But he says he is "disappointed" that the study did not highlight the need for farmers to increase the diversity of crops they grow as a means of adapting to climate change.

"One major strategy that farmers will have to use in future is diversity. So this is not just about having one or two high-yielding crops, but lots of different crops. More variability means greater resilience," he says.

References

  1. Burke, M. B., Lobell, D. B. & Guarino, L. Global Environ. Change advance online publication doi:10.1016/j.gloenvcha.2009.04.003 (2009).

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Gilbert, N. Averting a climate-led food crisis in Africa. Nature (2009). https://doi.org/10.1038/news.2009.585

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  • DOI: https://doi.org/10.1038/news.2009.585

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