Productivity-boosting agricultural innovations in Africa could lead to an increase in global deforestation rates and carbon emissions, a Purdue University study finds, contrary to historical impacts of similar ag technology improvements that have typically lead to lower emissions.
Generally, gaining better yields in one area lessens the need to clear other areas for crops. This avoids extra land conversion that can raise the amount of carbon dioxide released into the atmosphere.
Agricultural advances in Africa, however, could have the reverse effect, said Thomas Hertel, a Purdue distinguished professor of agricultural economics.
"Increasing productivity in Africa – a carbon-rich region with low agricultural yields – could have negative effects on the environment, especially if agricultural markets are highly integrated," he said.
According to Hertel, his study highlights the importance of understanding the interplay between globalization and the environmental impacts of agricultural technology.
"They are deeply intertwined," he says.
Less land or more profit?
Debate surrounds the effects of agricultural innovation on the environment, Hertel noted. Some researchers suggest that more profitable farming will lead to greater GHG emissions and tropical deforestation.
Others say if more crops can be produced using less land, more natural land will be spared.
"We set out to determine who was right," Hertel said. "We discovered that both hypotheses can be valid – it depends on the local circumstances."
Along with researchers Navin Ramankutty and Uris Baldos, Hertel developed economic models to review the impacts of regional improvements in ag technology on land use and carbon emissions globally.
'Green revolution' impacts vary by region
The researchers' analysis showed that historical "green revolutions" in regions such as Latin America and Asia – in which better varieties of cereal grains produced dramatic gains in harvests – helped spare land and diminish carbon emissions compared with an alternative scenario without crop innovations.
The global effects of a green revolution in Africa, however, are less certain, Hertel said.
"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," he said. "But if markets become more integrated, faster agricultural innovation in Africa could raise global carbon emissions in the coming decades."
In an integrated world markets scenario, the researchers' analysis showed that ramping up agricultural productivity in Africa over the years 2025-2050 could increase global cropland expansion by about 4.4 million acres and global carbon emissions by 267 million metric tons.
Why is Africa different?
The sharp differences between the global impacts of a prospective African green revolution and those of previous green revolutions can be traced to several factors, Hertel said.
In an African green revolution, the relatively lower yields of African croplands would require more area to be converted to agriculture to make up for the displaced crop production in the rest of the world. The area converted would likely be carbon intensive and have a low emissions efficiency – that is, crop yields would be low relative to the carbon emissions released by converting the land to crops.
But the potential negative effects of an African green revolution will diminish over time, Hertel said. If sustained over several decades, agricultural innovation in Africa would eventually conserve land and decrease carbon emissions, especially if yields improved quickly.
The most carbon-rich land, however, should be immediately protected from conversion to cropland, he said.
"We need to prevent regions in Africa that are rich in carbon and biodiversity from being cleared for agriculture to avoid increasing emissions," he said. "Boosting yields brings many benefits, but increasing global food supplies while minimizing the environmental footprint of agriculture remains a major challenge."
Hertel's paper detailing the findings was published Sept. 8 in the Proceedings of the National Academy of Science.