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Decision and Policy Analysis Research Area – DAPA

Cocoa production in Ghana needs to confront heat and drought

Farmer in Ghana cutting a cocoa pod with a machete

How can we go beyond raising awareness of the negative implications of climate change for tropical cash crops and guide policies for adaptation? The project “Mainstreaming CSA practices in cocoa production in Ghana” proposes to use a transect approach to identify sites with high, medium and low climate change impacts and to develop appropriate strategies for each setting. Throughout the process local stakeholders are engaged to develop practices that are well suited to the local decision environment. Ultimately, the project seeks to develop incentives and support mechanisms that will drive farmer uptake of CSA at scale.

Last week at the kick-off workshop DAPA researcher Christian Bunn confronted local partners in Accra with the initial results of his research on the differential climate change impacts on various cocoa growing zones in Ghana. Previous studies had stopped short of providing information to guide adaptation at the required scale. A widely cited study by Peter Läderach and others first drew attention to the likely negative impacts of climatic changes on the main cocoa producers in Ghana and Ivory Coast (Fig. 1). A forthcoming study by Schroth and others (in collaboration with CIAT-DAPA) extended this research to West-Africa and showed that especially increasing dry season temperatures will be an issue.

Suitability changes for cocoa production in Ghana and Ivory coast.

Fig. 1 Suitability changes for cocoa production in Ghana and Ivory coast. Läderach et al. (2013): http://link.springer.com/article/10.1007/s10584-013-0774-8

For this project we want to examine the impacts on cocoa production in Ghana and develop hypotheses on the drivers of expected changes. This means providing stakeholders with the detail necessary to understand the impacts in Ghana. Confronting workshop participants with these results sparked a multi-stakeholder multi-level conversation about strategies to confront climate change and adapt that will be continued through this project.

The objective was to go beyond mapping changes in suitability to get a more differentiated picture. The methodology used here is novel and appears very promising to really take our understanding of climate change impacts a step further. First, a map of the current distribution of agro-ecological zones of cocoa production in Ghana was developed. From the two studies mentioned above we had a dataset available that describes the geographical distribution of cocoa production in Ghana. We used RandomForest clustering based on 20 climate variables to identify 5 agro-ecological zones of cocoa production in Ghana. Using the same algorithm we were able to map the spatial distribution of these zones (Fig.2).

RandomForest classification result of cocoa-AEZs in Ghana for current climate

Fig. 2 RandomForest classification result of cocoa-AEZs in Ghana for current climate

Of course, once we can map the current distribution we can also map the future distribution. We chose data from 6 global climate models that are representative of the range of potential changes to the climate in Ghana (e.g. high/low precipitation increases, high/low temperature increases). For these data we also mapped the distribution of the agro-ecological zones and generated a consensus map based on the modal (most frequent) value across all the results (Fig. 3).

RandomForest classification result of cocoa-AEZs in Ghana for 2050s climate

Fig. 3 RandomForest classification result of cocoa-AEZs in Ghana for 2050s climate

Under current climatic conditions Ghana is equally divided into the 5 zones. The Lake Volta region has a long dry season and high maximum temperatures compared to other cocoa zones. Central Ashanti has comparatively cool minimum temperatures. West of Accra the climate for cocoa is characterized by relatively high annual precipitation and little temperature variation. This is in contrast to the Northern zone which for a cocoa zone has low annual precipitation and a long dry season.

Identification of zones with high, intermediate and low climate change impacts

Fig. 4 Identification of zones with high, intermediate and low climate change impacts

This latter zone will be most likely hit by climate change (Fig. 4). Participants at the workshop confirmed that the climate in this zone is not ideal for cocoa production. Farmers nevertheless keep investing in production because the soils are regarded as very good for cocoa and economic incentives are favorable. Further South the climate of the future is likely to become much drier. Especially length and severity of dry season could become an issue. All climate models agree on rising temperatures so that all zones with moderate maximum temperatures disappear. The climate for cocoa in the future in Ghana will be a hot one. Towards Southern regions the climate will be less variable and wetter. However, workshop participants raised doubts whether cocoa could have a future in these regions. The soils in this region are just too bad. The projected increased rainfall also raised strong concerns about increased erosion of soils.

Throughout the project we will continue to engage in these dialogues to refine our work. We will work with partners in the different impact zones with high, medium and low climate change impacts to develop site specific adaptation strategies. After all, the conclusion is that cocoa production has a future in Ghana. When looking at the net changes, equal areas see favorable climatic changes as areas with negative impacts (Fig. 5). However, only if adaptation is done right will farmers be able to avoid harsh consequences on production.

Transition of cocoa AEZs from current to 2050s climate.

Fig. 5 Transition of cocoa AEZs from current to 2050s climate.

For further information on this work please contact Christian Bunn (CBunn-at-CGIAR-dot-org).

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