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Predicting and coping with climate change in Africa

Changes in the rainy seaon have led this Nigerian farmer to start growing cassava instead of maize. (WRENmedia)
Changes in the rainy seaon have led this Nigerian farmer to start growing cassava instead of maize.
WRENmedia

For farmers in Africa, change is in the air. But, while many look to the heavens for the change to be favourable, Dr. Kai Sonder, GIS (Geographic Information Systems) expert at the International Institute of Tropical Agriculture, IITA in Ibadan, Nigeria, is using information relayed by satellites stationed high above the earth, as well as outputs from global climate models, to find answers to Africa's most pressing problems. Monitoring the trends in rainfall and temperature in different regions of Africa, Sonder is part of a team of scientists that is recommending new farming practices to ensure food security across the continent.

Adapting to survive

Adeshina Adeyinka, now vice-president of the cassava growers association for West Ibadan in Oyo State, Nigeria, used to grow maize for commercial purposes until 2003 when, due to delayed rainfall, 200 hectares of maize was completely lost. Prior to this, farmers had always planted maize in March, at the beginning of the wet season. "That has always been the practice as far back as I can remember," Adeyinka says. "But since the rainfall pattern is becoming very unpredictable, we now focus more on cassava."

A neighbour, Odebo Ogunlade, who has farmed for over 25 years, agrees. "Rain used to start in March and end in October. But about a decade ago, rain started falling at any time of the year, January to December. We no longer have a definite dry and rainy season. Though rainfall is more, it is usually not sufficient during the first quarter to start planting. We now start planting at the end of April."

Reeling from global warming

Predictions for suitability for banana production in Africa to 2080. Data provided by Robert Hijmans, UC Davis, USA.<br />click picture for more details.
Predictions for suitability for banana production in Africa to 2080. Data provided by Robert Hijmans, UC Davis, USA.
click picture for more details.

Climate variability, rather than climate change, is how Kai Sonder prefers to describe the current situation in Africa. But he confirms that rainfall is becoming more unpredictable. "Global warming is expected to cause less rainfall in some areas and more of it in others. In Zimbabwe, Malawi and parts of Mozambique, for example, people have a high dependency on maize. But droughts are becoming more frequent and causing heavy losses."

Some climate models have also predicted very serious changes for West Africa, with the Sahel region "already reeling under the effect of climate variability," according to Sonder. In response, IITA has advised farmers to plant more cassava, cowpea and sorghum, which are all relatively drought-tolerant.

But how much certainty can there be about African climate change over the coming decades? Currently there are no climate change models specific to Africa, not least because collection of sufficient data for calibration is problematic: weather stations are very scarce, and years of civil war have hampered data recording across large parts of the continent. As a result, scientists at IITA rely on information extracted from global climate models, the accuracy of which is judged by how well they have predicted the climate in the past. "For example," says Sonder, "we look at how well the models predict the climate in the last 100 years. If they do that well, we assume they would also predict the future well, but we do not know that for sure."

Preparing for change

While IITA is primarily concerned with climate changes that may unfold over the next 50 to 100 years, developing policies to prepare for those changes should, Sonder believes, be an immediate priority. Pointing to a map on his computer screen, he indicates a band made up of chocolate and lighter hues of brown stretching across the Sahel. It illustrates how a crop - in this case a cowpea variety - successfully introduced to a small area of Burkina Faso, has the potential to succeed in all the shaded areas, where similar conditions of soil, temperature and rainfall are found.

Kai Sonder (right) confirms to West African journalists that rainfall in the region is becoming more erratic. (WRENmedia)
Kai Sonder (right) confirms to West African journalists that rainfall in the region is becoming more erratic.
WRENmedia

By careful analysis of problems and extrapolation of solutions from smaller to larger areas, IITA's work should allow policymakers to recommend changes in current farming practices. For Sonder, this is all necessary work if millions of people are to be prepared for the future, particularly as he emphasises that, "many areas of Africa are already suffering under adverse effects of what climate change is predicted to bring for larger areas."

However, in the shorter term, Sonder believes farmers need reliable information about each coming season, since this ought to determine which crops to plant and when. The use of mobile phones to communicate market prices in Kenya and Uganda offers a model for how such information might be spread widely and quickly.

Written by: Oluyinka Alawode and Adeleke O'Adeyemi

Date published: May 2009

 

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The New Agriculturist is a WRENmedia production.

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