BARCELONA (Thomson Reuters Foundation) - Innovation in African agriculture could - unlike other green revolutions - lead to more deforestation and higher carbon emissions, researchers have warned.
Historically, better agricultural technology has protected land and decreased carbon emissions in regions such as Latin America and Asia, because improved yields lessen the need to clear new areas for crops.
The impact in Africa would depend on whether global markets become more integrated, the team from Indiana-based Purdue University wrote in the online issue of the Proceedings of the National Academy of Sciences this week.
"If the future global economy remains as fragmented as it has been historically - a world of very distinct agricultural markets - then a green revolution in Africa will lower global carbon emissions. But if markets become more integrated, faster agricultural innovation in Africa could raise global carbon emissions in the coming decades," agricultural economics professor Thomas Hertel said in a statement.
Under that scenario - where it is cheaper to grow more crops in Africa - boosting agricultural productivity on the continent from 2025 to 2050 could increase global cropland by 1.8 million hectares (4.4 million acres) and global carbon emissions by 267 million tonnes.
That is because Africa's lower yields would require more land to be converted to grow crops than elsewhere in the world, and that land would release relatively high levels of carbon dioxide, the study said.
But the potential negative effects of an African green revolution would diminish over time, and if sustained for several decades, such a transformation would eventually conserve land and decrease carbon emissions, especially if yields improved quickly, the researchers said.
In the meantime, land with high stocks of carbon - like tropical forests - should be protected from conversion for farming, they argued.
"We need to prevent regions in Africa that are rich in carbon and biodiversity from being cleared for agriculture to avoid increasing emissions," Hertel said.
"Boosting yields brings many benefits, but increasing global food supplies while minimising the environmental footprint of agriculture remains a major challenge."
(Editing by Timothy Pearce: email@example.com)