Adaptation measures for crop production in response to climate variability and change: An explorative policy study

The Cameroonian agricultural sector, a critical part of the local ecosystem, is potentially vulnerable to climate change raising concerns about food security in the country's future. This study assesses the potential impacts of greenhouse gas climate change, as well as the fertilization effect of increased atmospheric CO2 on crop yields. A methodology is applied where transient diagnostics of two atmosphere-ocean general circulation models, the NASA/Goddard Institute GISS and the British HadCM3, are coupled to a cropping system simulation model (CropSyst) to simulate current and future (2020, 2080) crop yields for selected crops viz. bambara groundnut (Vigna subterranea), groundnut (Arachis hypogaea), maize (Zea mays), sorghum (Sorghum biolor) and soybean (Glycine max)) in eight agricultural regions of Cameroon. For the future, substantial yield increases are estimated for bambara groundnut, soybean and groundnut, while little or no change or even decreases for maize and sorghum yields, varying according to the climate scenario and the agricultural region investigated.

Adaptation policies may be able to mitigate some of this vulnerability. Taking the “no regrets” principle (Hoffmann, 2007) into consideration, we explore the advantages of specific adaptation strategies specifically for three crops viz. maize, sorghum and bambara groundnut, under GISS A2 and B2 marker scenarios only.

The results suggest that changing sowing dates may be ineffective in counteracting adverse climatic effects because of the narrow rainfall band that strictly determines the timing of farm operations in Cameroon. In contrast, the possibility of developing later maturing new cultivars proved to be extremely effective in offsetting adverse impacts, giving the highest increases in productivity under different scenario projections without management changes. For example, under climate change scenario GISS A2 2080, a 14.6% reduction in maize yield was converted to a 32.1% increase; a 39.9% decrease in sorghum yield was converted to a 17.6% increase, and for bambara groundnut (an under-researched and underutilised African legume), yields were almost trebled (37.1% increase above that for sowing date alone (12.9%)) due to increase length of growing period and the positive effects of higher CO2 concentrations. These results highlight the need to search for and promote new crop options as well as practices and methods that make maximum utilization of prevalent crop and climatic combinations. The results provide useful guidance and motivation to public authorities and development agencies interested in food security issues in Cameroon and elsewhere.