June 5, 2008 —Before policymakers can respond appropriately to climate change, they need to be able to reliably gauge the varying impacts of a warming planet in various locations.
New research supported by the World Bank has quantified for the first time how climate change might affect net farm revenue from both crops and livestock across 16 agro-ecological zones in Africa.
Researchers Seo, Mendelsohn, Dinar, Hassan and Kurukulasuriya show that future farm incomes in Africa are climate sensitive, and will be severely threatened in the event of extreme climate change scenarios.
Farmers will be able to tolerate—or perhaps take advantage of—mild or moderate climate change through various adaptation measures, including switching among crops and livestock species, or between crops and livestock.
Under certain climatic conditions, livestock species may provide more flexibility to some farmers and could help offset losses in crop income.
“The key question is whether farmers have access to the best means of adapting to climate change in their local context,” said Ariel Dinar, Lead Economist in the World Bank’s Development Research Group.
“In helping farmers adapt, policymakers should address the most vulnerable zones within a country first, taking into account their population, income volatility, and the size of the impact. ”
The impacts of climate change will not be evenly spread across Africa
Farms in some agro-ecological zones will benefit; while those in others will lose.
For example, farms in moist or dry savannah are vulnerable to higher temperature and less rainfall...
...while farms in humid forest areas gain even from severe climate change.
Dinar and fellow researchers studied a sample of over 9,000 farmers in 11 countries in Africa—investigating their current choices to adapt to climate variability—and used the FAO’s classification of agro-ecological zones to structure their conclusions.
Africa’s future distribution of crops will differ depending on the type of climate change scenario that occurs:
In a very hot, dry scenario, farmers will grow more fruit and vegetables across traditionally humid parts of Africa, but less of these in lowland semi-arid areas.
In a mild and moist scenario, farmers will grow more millet, except in the lowland dry savannah and lowland semi-arid zones.
In all scenarios, maize will be chosen less often in all zones.
Wheat will decline across Africa as climate warms.
Given that these simulations are based on the types of decisions farmers are already making, this is potentially very useful information for policymakers. It could help them to plan for the infrastructure, institutions and funds that may be needed in the future.
Farmers adapt their decisions about livestock based on the climate. As temperature warms, farmers will raise more livestock and switch species. However, if rainfall increases, they will own less livestock.
Research findings show that
As temperature rises, African farmers tend to move away from chickens and beef and dairy cattle towards goats and sheep.
As rainfall increases, they tend to move away from beef and dairy cattle and sheep towards goats and chickens.
With climate change, livestock ownership will increase across Africa, except in the deserts.
In a very hot and dry scenario, the largest increase in livestock adoption will happen in the high elevation zones.
Species choice varies across the different agro-ecological zones. For example, in a mild and moist scenario, sheep ownership decreases in deserts, at high elevation, and in lowland humid regions, but increases in West Africa and mid-elevation areas in southern Africa.
“Besides taking into account these varying adaptation choices by zone, policymakers will also need to consider changes in global prices for livestock and local changes in population, income and level of development,” said Robert Mendelsohn of the School of Forestry and Environment Studies at Yale University.
Farmers’ choice of farm types is climate sensitive, and so decisions on farm type are likely to change with changes in the climate. Future climate change will in fact change the distribution of farms types across Africa.
For example, simulations show that warmer temperatures in high or mid-elevation zones will increase the choice of rainfed farms that raise both crops and livestock.
Knowing the likelihood of selecting a given farm type in each agro-ecological zone across Africa will help policymakers to include in their policy packages incentives for farmers to move to certain farm types as climate changes, so that they maximize profits.
Future research directions
Research on agro-ecological zones so far has been conducted assuming that these zones are stable. However, since agro-ecological zones are by definition a function of climate, they may shift as the climate changes.
Future research will attempt to estimate the impact of climate change by measuring the effect it has on the probability that a given location remains in the same zone. If warming causes districts to shift from high to low productive uses (or vice-versa), it may cause damage.
Shifts in zones with changes in climate mainly affect poor people, as they may degrade or improve land quality and use, and lead to migration. Knowing more about these potential aspects of climate change is essential to policy in rural Africa.