Impacts of climate change on agro-climatic suitability of major food crops and crop diversification potential in Ghana

Abstract

11Crop diversification is a promising climate change adaptation strategy for food production stability. 12However, without quantitative assessments of where, with which crop mixes and to what extent 13 diversification is possible now and under future climatic conditions, efforts to expand crop diversification 14 under Nationally Determined Contributions (NDCs) and National Action Plans (NAP) are unsystematic. 15In this study, we used extreme gradient boosting, a machine learning approach to model the current 16 climatic suitability for maize, sorghum, cassava and groundnut in Ghana using yield data and 17 agronomically important variables. We then used multi-model future climate projections for the 2050s and 18 two greenhouse gas emissions scenarios (RCP 2.6 and RCP 8.5) to predict changes in the suitability range 30 31 32 2 35 Agricultural intensification, crop diversification, irrigation, improved crop varieties and other agronomic 36 management strategies are needed to stabilize or enhance food production now and under projected 37 climatic conditions. Of these options, crop diversification requires special attention because it can stabilize 38 national and local food production [3-6], improve dietary choices [7-10], increase on-farm ecosystem 39 services [11-14], avert micro-nutrient deficiencies and improve household health outcomes [7, 15] and 40 increase incomes of smallholder farmers [16-18]. 41 42 Studies have shown that crop diversity contributes to resilience through a type of "insurance" where a 43 failure in one crop is mitigated by another crop/cultivar and also through more efficient resource 44 partitioning at various scales [5, 19, 20]. As such, crop diversification has been shown to be beneficial to 45 building climate resilience in many countries such as in China [21], Canada [22], Kenya [23], Ethiopia 46 [24], Malawi [9, 18], Zimbabwe [25] and also Ghana, [26, 27]. Crop diversification is achieved through 47 multiple cropping where farmers grow two or more crops in sequence (relay cropping) or together 48 (intercropping and mixed cropping) within the same year. The ability of farmers to diversify is based on 49 the concurrent (for intercropping) or sequential (for relay cropping) biophysical suitability of the crops in 50 their area. 51 52 Crop suitability is a measure of the climatic and other biophysical characteristics of an area to sustain a 53 crop production cycle to meet current or expected targets [28, 29]. When combined with climate 54 projections, suitability assessments are used to gauge shifts in crop potential under climate change [30, 55 31]. Despite massive developments in agricultural production technology, weather and climate still play a 56 significant role in influencing agricultural production in Africa and elsewhere [32-34]. In particular, under 57 rain-fed conditions the production potential of a crop depends on the climatic conditions of an area. 58 Therefore, each crop will thrive within a specific climatic envelope that can be enhanced by management 59 -yet climate cha...