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Climate Change Could Impact Global Maize Production - 2003-05-21


A new study forecasts shortages in the production of maize in Latin America and Africa if current climate trends continue. Such losses could affect 140 million people in developing countries by 2055.

Simulated maize yields (baseline) and changes to 2055 for Africa and Latin America

The study uses a computer model designed specifically to analyze maize production to predict future harvests in Latin America and in Africa, where maize is an important staple for humans and livestock.

Co-author Philip Thornton with the International Livestock Research Institute in Nairobi, Kenya, explains how the model works.

"What we did was to take those predictions from the very complex models and then downscaled them to the level of the plot, which is the level at which this crop simulation runs," he explained. "And then by comparing what happens with weather that is characteristic of today with what is characteristic in 2055, then we can get an idea of what may be happening with changes in maize yields and maize yield variability."

According to the study, maize harvests could fall 10 percent by 2055. But the decline would not be evenly spread. Rising global temperatures and shifting rainfall patterns would vary greatly across farming areas. So, much so, says co-author Philip Thornton, that when scientists zoomed in to focus on small landholders, a much different picture emerged.

THORNTON: For some producers the consequences could be devastating, particularly in eastern southern Africa where maize is the staple food. And even small decreases in household maize production could have big impacts on calorie intake. It could also have a big impact in terms of the feed available for people's livestock in the dry season. And of course this family of livestock needs to be fed, and if maize is not going to produce the calories then these households must have access to other sources of nutrients both for themselves and for their animals.

SKIRBLE: Did these findings surprise you when got down to the plot or farm level?

THORNTON: I think they did in many ways, particularly this difference if you look at the country level and then look at all these little variations, they all seem to average out. But it is when you look at particular places, particular locations you can see some people are going to be okay in the sense that maize will still be a profitable crop. But looking at these other places it is almost like some householders may have to move out of maize production entirely."

SKIRBLE: Is this study a call for action, to (identify needs in the agricultural sector?)

THORNTON: I think it is a call for action really. What we are trying to say (with this study) is that we are getting to the stage where we have tools and methods at our disposal to do a much better job than we have in the past to identify what the household impacts of climate change may be. That is important to know that. Even more important is to know what the problems are and what we are going to do about them. Given that with agriculture research there are very long lags between, for example, identifying the need to develop a new drought (tolerant) variety of maize and that variety being available for small (land) holders in their plots. That gap or lag may be from anything between 10 to 15 years. And so, the earlier that we can identify where potential problems may lie then the sooner we can do something about it to get solutions into small landholders fields.

Philip Thornton says the study points out the need for more research to help small landholders who are most at risk to adapt to the impact of climate change.

"For many of these maize producers maize is just one of the enterprises that they are involved with," he explained. " Most small holders will grow a range of crops and they may have different type of livestock. So, really the maize production story is important, but it is certainly not the whole story. And it may be that some of these households are growing crops where the impact of climate change may be very different from that of maize."

Philip Thornton is a scientist with the International Livestock Research Institute. The study was published this week in the journal, Global Environmental Change."

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