Bamako — Farmers in six African countries - Burkina Faso, Chad, Mali, Niger, Senegal and Sierra Leone - may be unable to grow maize by 2050, researchers have predicted.

Using historical climate data, maps of crop cultivation and climate models taken from the Intergovernmental Panel on Climate Change Fourth Assessment Report, they found that by 2050 growing seasons in Africa will be hotter than almost all countries on the continent have ever experienced - even if carbon emissions are dramatically reduced.

The research, published last month (4 June) in Global Environmental Change, compared the projected climates with present conditions and found that most countries will experience conditions similar to those existing now in other nations. For example, Lesotho - which has one of the continent's coolest climates - could turn to the maize varieties being cultivated in Mali, one of Africa's hottest countries.

But six of Africa's hottest countries, most of which are in the Sahel region, may have nowhere to turn as few countries currently experience their extremely hot projected climates. The researchers warn that these countries may therefore need to switch to more heat- and drought-tolerant crops such as sorghum and millet.

David Lobell, one of the authors and a senior researcher at the Program on Food Security and Environment of the US-based Stanford University, told SciDev.Net that these countries need to work together to grow seeds in a productive way.

He suggests that Mali, for example, should try to diversify into millet and sorghum and avoid depending on other countries for seeds. Farmers should also be educated about the benefits of sorghum and millet, and Mali must share genetic resources with other countries, he adds.

But decades of neglect of African crop genebanks means that breeders today don't have access to the varieties of Africa's staple crops - maize, millet and sorghum - that are likely to be most helpful in allowing farmers to adapt to climate change, the researchers say.

"The genebank collections from many areas that are likely to have the widest range of diversity are either incomplete or non-existent," says Luigi Guarino, senior science coordinator at the Global Crop Diversity Trust and co-author of the paper.

Guarino suggests collaborating on sourcing and using novel genetic material from Africa and further afield to breed better varieties. "They could look in national and, even better, international genebank collections for potential suitable material."