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Crops of central importance to many of the worlds poor could be greatly harmed by climate change within the next two decades, according to a new study by researchers at Stanford University’s Program on Food Security and the Environment (FSE). The results are scheduled for publication on February 1st in the journal Science.

“The majority of the world’s one billion poor people depend on agriculture for their livelihoods,” said lead author David Lobell, senior research scholar at FSE. “Unfortunately, agriculture is also the human enterprise most vulnerable to changes in climate. 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.”

Climate change and hunger hotspots

Agricultural systems around the developing world are incredibly diverse, and will likely respond to a changing climate in different ways. And while the potential impact of climate change on the worlds poor is a topic with wide and growing interest, there remains much uncertainty about where specifically threats will be greatest, and thus where investments in adaptation should be initially focused.

In the study, the researchers combined data on what poor people eat, past relationships between crop harvests and climate variability, and projections of climate change from 20 climate models to identify which crops in which regions are most under threat by the year 2030. The study identified two major “hunger hotspots” – Southern Africa and South Asia – where many of the worlds malnourished are currently located and where climate impacts on agriculture look particularly dire.

“We were surprised by how much and how soon some of these regions could suffer if we don’t adapt”, said Marshall Burke, study co-author and researcher at FSE. “For example, our study suggests that Southern Africa could lose more than 30% of its main crop, maize, in the next two decades – with possibly devastating implications for food security in the region”. Potential losses in South Asia are also significant, with projected losses of up to 10% or more for numerous regional staples, including millet, maize, and rice. “For poor farmers on the margin of survival, these losses could really be crushing,” noted Burke.

Prioritizing investments

With large projected losses in many important poor regions, adapting agriculture to a changing climate will be a crucial global task. By looking systematically across regions and at a wide range of crops of importance to the poor, the researchers hoped to provide a way to prioritize investments in adaptation. “Say you’re an organization with finite resources who is interested in alleviating hunger and concerned about the effects of climate change,” said Lobell. “Our study asks: given the data we have, where would you spend your money first? And while the data are not perfect, we have to make decisions based on available data.”

“This study arrives at a particularly useful time,” adds co-author Rosamond Naylor, director of the Program on Food Security and the Environment. “The international donor community is starting to invest once again in agricultural productivity in the developing world, and our study will help show where these investments might be the most worthwhile. We know we can’t do everything right away, but this helps us know where to start.”

While the study results point to clear areas where urgent investments in agricultural adaptation are needed, such as Southern Africa and South Asia, it also points to other areas where uncertainties surrounding impacts are higher, and thus where investment priorities might differ among institutions. “Areas of West Africa and the Sahel stand out as regions with very high rates of food insecurity, with a very high dependence on agriculture, but also with a fair amount of uncertainty regarding climate change impacts,” notes Burke. “For these regions you get half the climate models telling you it’s going to get wetter, and the other half giving you the opposite. As a result, our study shows the potential for very bad impacts in these regions, but with much less certainty than in other regions.” Results also pointed to a few developing regions that could benefit in the short run from climate change, such as the temperate wheat-growing regions of China.

Adapting for change

In the face of these uncertainties, where should organizations be investing money, and what kind of adaptation investments make the most sense?

“There are the sure bets, such as maize in Southern Africa and rice in southeast Asia where all models agree that impacts will be negative”, explains Lobell. “Then there are those cases where things could get really bad, such as for sorghum in the Sahel or millets in central Africa, but where we are less certain. In the end, if a choice has to be made, individual institutions will have to decide for themselves whether to pursue the sure bets, or the riskier but potentially high-payoff investments”.