CHICAGO (AFP) — Climate change will cause severe crop losses in Africa and Asia within the next 20 years unless farming practices are changed, a study released Thursday has found.
Those crop losses could lead to food shortages and a loss of livelihood among the world's poorest people, the authors warned.
And since it typically takes 15 to 30 years to for major agricultural investments to be fully realized, work must start soon to help subsistence farmers increase their yields and switch crops, the study published in Science magazine said.
"The majority of the world's one billion poor depend on agriculture for their livelihoods," said lead author David Lobell of Stanford University's Program on Food Security and the Environment.
"Unfortunately, agriculture is also the human enterprise most vulnerable to changes in climate," he said.
"Understanding where these climate threats will be greatest, for what crops and on what time scales, will be central to our efforts at fighting hunger and poverty over the coming decades."
Lobell and his colleagues used 20 different climate change models to determine the most likely impact of global warming on agriculture in 12 regions where the bulk of the world's malnourished people live. This included much of Asia, sub-Saharan Africa, the Caribbean and Central and South America.
"To identify which crops in which regions are most under threat by 2030, we combined projections of climate change with data on what poor people eat, as well as past relationships between crop harvests and climate variability," Lobell explained.
They found that southern Africa could lose more than 30 percent of its main crop maize, while South Asia's production of regional staples including millet, maize and rice was projected to drop by 10 percent or more.
"We were surprised by how much and how soon these regions could suffer if we don't adapt," said co-author Marshall Burke, also of Stanford University.
"For poor farmers on the margin of survival, these losses could really be crushing."
The picture is less certain in other areas such as parts of West Africa where it is unclear how global warming will impact the local climate.
"For these regions, you get half of the climate models telling you it's going to get wetter and the other half giving you the opposite," Burke said.
"As a result, our study raises the potential for very bad impacts in these regions but with much less certainty than in other regions."
A few developing regions, such as the temperate wheat-growing areas of China, could actually benefit in the short run from climate change, he added.
While relatively inexpensive changes, such as switching crops or altering planting seasons, could trim the losses, "the biggest benefits will likely result from more costly measures, including the development of new crop varieties and expansion of irrigation," the authors wrote.
"Consideration of other social and technological aspects of vulnerability, such as the existing adaptive capacity in a region or the difficulty of making adaptations for specific cropping systems, should also be integrated into prioritization efforts," they concluded.
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