Climate Change and Global Agricultural Potential Project: A Case of Kenya

Fischer, G. & van Velthuizen, H.T. (1996). Climate Change and Global Agricultural Potential Project: A Case of Kenya. IIASA Working Paper. IIASA, Laxenburg, Austria: WP-96-071

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Abstract

Kenya is endowed with a wide range of agro-ecological conditions, varying from hot arid lowlands to cool humid highlands. As expected, the results of the impact analysis of climate change and increases of atmospheric carbon dioxide, therefore show a wide spectrum of impacts on land resources make-up and agricultural production. At the sub-national level results of impacts on agricultural productivity vary substantially both in terms of magnitude and direction.

At present, agricultural production in the low altitude areas in Kenya is mainly constrained by water availability, highland areas are constrained by low temperatures and locally by water availability, while in parts of central and western Kenya rainfall in excess of optimal levels occurs.

Rising temperatures, without corresponding increases in precipitation to balance the increased plant water requirements due to higher evapotranspiration may lead to dramatic reductions in agricultural production potential, especially in eastern and southern Kenya, i.e., in parts of Eastern province, North-Eastern province and Coast province. In central and western Kenya temperature increases would result in larger extents of lands with cultivation potential, because some higher altitude areas would become suitable for cropping. This, together with potentials for higher cropping intensities in these highland areas, more than outweighs effects of diminished moisture conditions, even in scenarios assuming no change in precipitation. Under such conditions in the presently humid areas (>270 days of growing period), diminished wetness, in instances, could reduce the potential impact of pest and disease constraints.

Results of the impact assessment suggest that the national level food productivity potential of Kenya may well increase with higher levels of atmospheric CO2 and climate change induced increases in temperature, provided this is accompanied by some increase in precipitation as predicted by several global circulation models. If no balanced increase in precipitation were to take place then the impact on agricultural productivity in the semi-arid parts of Kenya could be devastating.

Although land productivity in Kenya as a whole appears most likely positively affected by climate change, impacts vary considerably depending on location. Negative impacts are expected to occur in Coast province and North-Eastern province. The main reasons being:

-- Exceeding optimal temperature ranges for photosynthesis and growth;

-- Shortening of cereal growth cycles and periods of yield formation;

-- Increased water stress.

For Central province, Nairobi area, important parts of Eastern province, Nyanza province and Western province the impacts are mostly positive. However, some negative impacts in western Kenya may occur due to pest and disease damage and worsening of workability conditions due to increased wetness. The high-potential agricultural lands in central and western Kenya will dominate the agricultural production potential even more under projected climate change conditions. The main reasons of positive impacts appear to be:

-- Temperature increase in the mid/high altitudes, enlarging the area with crop production potential;

-- Increased cropping intensity potentials;

-- CO2 fertilization.

In Rift Valley province, comprising of a wide range of thermal and moisture conditions, impacts are mixed. Negative impacts are, for instance, expected in Laikipia and Narok while positive impacts are anticipated in Nakuru and West Pokot.

Despite of overall positive effects for Kenya as a whole, impacts of climate change on land productivity may intensify regional disparities. Therefore, preparedness is critical in order to:

-- take advantage of potential blessings of climate change and increased atmospheric CO2 concentrations;

-- mitigate likely negative impacts in low-lying and semi-arid areas;

-- cope with the socio-economic consequences of changing patterns of land productivity.

These observations are consistent with short and medium term considerations for sustainable development, emphasizing the critical need for careful planning and protection of high potential areas.

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