The Impact of 1.5 & 2oC warmingon crop suitability over West Africa

Temitope S. Egbebiyi, O. Crespo, C. Lennard

Climate System Analysis Group, University of Cape Town

Climate Smart Agriculture 2017, Johannesburg, South Africa

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West African Climate

West African Monsoon (WAM), main source of moisture (Nicholson, 2013)

divided into three major ecological zones namely:

✓ Guinea - Lat. 4-8oN, 1500-3000mm/year

✓Savannah - Lat. 8-12oN, 700-1200mm/year

✓Sahel - Lat.12-16oN, below 700mm/year (Abiodun et al., 2012a)

Rainfed agriculture is crucial to the economy and livelihood of the inhabitants of West Africa (Omotosho & Abiodun, 2007, Roudier et al., 2011, Diasso & Abiodun, 2015).

Figure 1: West African topography and

ecological zones, designated as Guinea,

Savannah and Sahel, respectively. (Abiodun et

al., 2012a)

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• Extreme climate (e.g. extreme rainfall, droughts) impact on crop yield such as damagecaused to 300 hectares of crops in Burkina Faso in 2009, about 7,000 hectares of rice fieldworth US$ 2 million in Guinea; 201,600 crop hectares in Benin (Panthou et al. 2012,Sighomnou et al., 2013; WMO Report, 2015) in the last few decades.

• Temperature increase between 1.5 - 4oC is projected by 2100 due to the increase ingreenhouse gas emission (World Bank Report, 2013).

• 1.5-2oC temperature increase will have significant impact on agriculture over the region(Schulesser et al., 2016).

• Highly sensitive and vulnerable to climate change, including low adaptive capacity (IPCC,2013)

• There is a need for more information on how 1.5 and 2oC warming will impact crop growthsuitability over West Africa. This information is important to improve crop yield and foodsecurity in the region

• Six crops namely, Maize, Cassava, Millet, Cowpea, Groundnut and Plantain are consideredowing to their economic importance and FAO statistics over the region.

An exposed and sensitive West Africa

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Data and Methods

Data

• Minimum and mean monthly temperature (tmin & tmean) and total monthly precipitation.

• 10 CMIP5 GCMs downscaled by SMHI-RCA4 under RCP8.5 emission scenario & CRU as

observed data

• FAO EcoCrop monthly crop suitability threshold for six crops namely, Maize, Cassava,

Millet, Cowpea, Groundnut and Plantain (Hijmans, 2001).

Methods

• A thirty-year running average to calculating the year of reaching 1.5 and 2oC over the

region using a 14 and 15 year before and after the calculated year respectively.

• The resulting 12 (tmin, tmean and precipitation) values over the 30-year window calculated

time of reaching 1.5 and 2oC warming were used as input and to force EcoCrop model in

computing the suitability index over West Africa and to assess how 1.5 and 2-degree

warming will impact crop suitability across the agro-ecological zones of West Africa under

RCP8.5.

• EcoCrop Suitability index ranges from 0 to 1.

0.0> not suitable >0.2> very marginal >0.4> marginal >0.6> suitable >0.8> very suitable.

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Crop suitability, recent past

Figure 2: Spatial distribution of crop suitability over West Africa for the period 1971-2000 as simulated by

EcoCrop with climate input from RCA4 for (a) Millet, (b) Cassava, (c) Groundnut, (d) Cowpea, (e) Maize

and (f) Plantain.

0.0> not suitable >0.2> very marginal >0.4> marginal >0.6> suitable >0.8> very suitable.

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Crop suitability change, + 1.5 oC

Figure 3: Projected change in crop growth suitability with 1.5-degree warming over

West Africa under RCP 8.5 scenario.

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Crop suitability change, + 2.0 oC

Figure 3: Projected change in crop growth suitability with 2-degree warming over West

Africa under RCP 8.5 scenario.0.0> not suitable >0.2> very marginal >0.4> marginal >0.6> suitable >0.8> very suitable.

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Crop suitability at +2 oC

Figure 3: Projected Impact of 2-degree warming on crop growth suitability over West

Africa under RCP 8.5 scenario.0.0> not suitable >0.2> very marginal >0.4> marginal >0.6> suitable >0.8> very suitable.

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Conclusion

• RCA4 simulated crop suitability with modelled climatology (RCA4-EcoCrop) values gives a realistic representation of suitability with observed climatology (CRU-EcoCrop) over West Africa (Figs. 1).

• higher suitability are observed and simulated south of 14oN, except for Millet only suitable in the savanna zone around the northwest boundary of Ivory coast and Ghana.

• The projected impact of 1.5oC warming on crop suitability may results in suitability increase (up to 0.1) for all crops notably over the region Cowpea and Groundnut while decrease in suitability are also projected for crops like Cassava, Plantain and Maize mainly south of 10oN.

• It further showed a shift in the spatial suitability distribution of crops within the three AEZs mostly towards the Sahel zone.

• Similar pattern are projected with 2oC warming but with a higher magnitude in suitability index

• The impact of 1.5 & 2oC warming will lead to more suitable land for cultivation over West Africa and influence food security.

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Acknowledgements

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tsegbebiyi@gmail.com; EGBTEM001@myuct.ac.za

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Some References…..• Abiodun B. J, Adeyewa Z. D, Oguntunde P. G, Salami T. A and Ajayi V. O (2012a) Modelling the

impacts of reforestation on future climate in West Africa. Theor Appl Climatology DOI10.1007/s00704-012-0614-1

• IPCC, 2013: Climate Change (2013): The Physical Science Basis. Contribution of Working Group I tothe Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D.Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley(eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp.1535.

• Omotosho J, Abiodun BJ (2007) A numerical study of moisture build-up and rainfall over WestAfrica. Meteorol Appl, 14, 209–225

• Paeth, H., Fink, A. H., Pohle, S., Keis, F., Mächel, H., & Samimi, C. (2011). Meteorologicalcharacteristics and potential causes of the 2007 flood in sub-Saharan Africa. InternationalJournalof Climatology, 31(13), 1908-1926.

• Panthou, G., Vischel, T., Lebel, T., Blanchet, J., Quantin, G., & Ali, A. (2012). Extreme rainfall inWest Africa: A regional modeling. Water Resources Research, 48(8).

• Schleussner C F, Rogelj J, Schaeffer M, Lissner T, Licker R, Fischer EM, et al 2016Science and policy characteristics of the Paris Agreement temperature goal -Nature Climate Change.

• World Bank 2013. World Development Report (2013): Jobs. Oxford University Press, New York -Various years. World Development Indicators - Various issues, WB, Washington, D.C.

• World Meteorological Organization, WMO, (2015). The Climate in Africa: 2013. WMO-No. 1147, Geneva: WMO

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