Impact of climate change on staple food crop production in Nigeria
Valentina Mereu1,2 & Gianluca Carboni3 &
Andrea Gallo1 & Raffaello Cervigni4 & Donatella Spano1,2
Received: 12 October 2014 /Accepted: 28 April 2015 # Springer Science+Business Media Dordrecht 2015
Abstract Climate change impact on the agricultural sector is expected to be significant and extensive in Sub-Saharan Africa, where projected increase in temperature and changes in precipitation patterns could determine sensible reductions in crop yields and concerns for food security achievement. This study presents a multi-model approach to analysing climate change impacts and associated risks for staple food crops in Nigeria. Previous attempts to evaluate climate change impacts in Nigeria had mainly focused on a reduced number of crops, with analysis limited to single experimental fields or specific areas, and in many cases considering only a limited number of climate models. In this work, crop simulation models implemented in the DSSAT-CSM software were used to evaluate climate change impacts on crop production in different Agro-Ecological Zones, considering multiple combinations of soils and climate conditions, varieties and crop management. The climate impact assessment was made using an ensemble of future climate projections, to include uncertainty related to climate projections.
Even if precipitations could increase in most parts of Nigeria, this is not likely to offset the crop yield reduction due to the increase in temperatures, particularly over the medium-term period (2050), with yield decreases projected especially for cereals. The short-term effects are more uncertain and yields for cassava and millet might actually increase by 2020. Moreover, yield reductions are only partially mitigated by the direct effect of increased CO2 atmospheric concentration enhancing crop yield. In both periods and for all crops, there is a higher risk that crop yields may fall below the actual risk threshold.
DOI 10.1007/s10584-015-1428-9 * Valentina Mereu email@example.com 1 Department of Science for Nature and Environmental Resources, University of Sassari, via Enrico de
Nicola, 9, 07100 Sassari, Italy 2 Euro-Mediterranean Center on Climate Change, via Enrico de Nicola, 9, 07100 Sassari, Italy 3 Department of Crop Production, Agricultural Research Agency of Sardinia (AGRIS), Viale Trieste 111, 09123 Cagliari, Italy 4 Environment and Natural Resources (AFTEN) Africa Region, The World Bank1818 H Street, N.W.,
Washington, DC 20433, USA 1 Introduction
Sub-Saharan African (SSA) Countries, which have rural economies mostly based on rainfed and low-input agriculture, are particularly vulnerable to climate changes (Thornton et al. 2009;
Webber et al. 2014). Temperatures in Africa are expected to rise faster than the mean global increase during the 21st century and, especially in West Africa (WA), the projected timing of climate departure could occur 1 to 2 decades earlier than the global average (Mora et al. 2013;
Niang et al. 2014).
Changes in climatic conditions are very likely to reduce cereal crop productivity in SSA, with high differences in yield projections according to regional variability (Lobell et al. 2008;
Thornton et al. 2009; Roudier et al. 2011; Webber et al. 2014). Nelson et al. (2009) analysed simulations for all SSA regions, highlighting climate change impacts on cereal crop yields, ranging from 2 % for sorghum to 35 % for wheat by 2050. Similarly, the highest yield reductions are projected for wheat (−21 %) in the study of Ringler et al. (2010), while yields for millet and sorghum are projected to be slightly higher (1–2 %). On the contrary, crop yield reductions in SSA are projected by mid-century for sorghum and millet (−17 %), in the study of Schlenker and Lobell (2010).
Climate impacts on the main crops for WA are controversial and projected to be either positive or negative depending on the GCM, scenario and crop modelling approach considered (Roudier et al. 2011). Notwithstanding a good consensus among climate models in predicting increases in temperatures for WA, there is large uncertainty in projections of precipitations (Niang et al. 2014). Expected increases in temperatures may be the prevailing climate factor affecting crop productivity (Lobell and Burke 2008), because they are greater relative to projected precipitation changes (Schlenker and Lobell 2010; Tingem and Rivington 2009).
Among WA Countries, Nigeria accounts for half of the total population and is the main producer of maize, millet, sorghum and cassava (Jalloh et al. 2013). Moreover, Nigeria can be considered a representative case study of the WA, having all the range of climatic and vegetation types of this area (Adejuwon 2004): from the wettest Agro-Ecological Zone (AEZ), the Humid Forest, to the semi-arid zone of Sahel Savanna (Fig. 1). The agricultural sector in Nigeria drives the economy contributing for about 40 % of the Gross Domestic
Product (GDP) and employing 70 % of labour forces (NBS 2010). As reported in the
Agricultural Production Survey Report 2009 (NPAFS 2010), eighty percent of agricultural production is provided by cereals (mainly sorghum, millet, maize and rice) and root crops (cassava and yam). The production of sorghum and millet was mostly reported in the drier northern states of the Country (Borno, Kano, Zamfara and Kaduna for sorghum and Sokoto for millet). Rice production is prevalently in Niger, Kaduna and Kwara states while maize production, which is more widespread, is obtained especially in Kaduna (Northern Guinea
Savanna) and Niger. Cassava is mainly cultivated in the Southern states (Humid Forest and
Derived Savanna): Cross River, Enugu, Kogi, Benue and Ondo states.
Despite the prominent role of agriculture, Nigeria is still a net grain importer (Kuku-Shittu et al. 2013) and that makes it vulnerable to fluctuating world market prices and hence to food security risk. Moreover, food security is heavily endangered by an impressive demographic explosion, with population levels quadrupled in the last 50 years to 160 million persons (United Nations 2013). In recent years, climate variability affected agricultural production in several parts of the Country, causing frequent crop failures and decreases in yields due to the false start and early cessation of rains, droughts and increases in temperatures, which limit the growing season (Odekunle 2004; Adejuwon 2006). Crops and cultivars differ for their