Impacts of climate change on agro-climatic suitability of major food crops in Ghana

Although rainfall amounts are generally high in Ghana (over 800 mm in most years), pre- cipitation remains an important factor in determining crop potential. This is because of the cli- mate gradient in Ghana from the south to the north, and its intra-seasonal variation influencing the suitability of the different crops. For comparison, in China fit was observed that temperature-related variables as more important factors for maize suitability than precipi- tation [77], highlighting the local relevance of our results that cannot simply be extrapolated. We found that sorghum suitability is also influenced by the diurnal temperature range, which concurs with current understanding that sorghum is a more adverse weather tolerant crop. This tolerance is enabled by heterotic mechanisms that allow for greater biomass and yield production at a shorter period, ‘stay green’ mechanisms, and lodging and desiccation tolerance compared to other crops [78, 79]. 4.2 Individual and multiple crop suitability under climate change Of the four crops modelled in this study, groundnut suitability is the most resilient under cli- mate change, showing the smallest loss in suitable growing areas. This could be explained by groundnuts being legumes with a short growth period and whose harvested parts grow below ground and thus are partly protected by the soil from direct effects of warming. Groundnut viability is closely related to rainfall patterns [80, 81], particularly the amount of rainfall in the growing season due to the less extensive root system, and thus projected increases in rainfall

can directly increase suitability for groundnut production. This is especially so as the assess- ment of changes in agronomic variables show increased rainfall variability than changes in Table 5. Area and percentage of different levels of suitability of multiple crops in Ghana under current and future climates. Suitability Scenario Measure One crop Two crops Three crops Four crops Very high Current Area(km2) 98978 41888 3716 0 % 41 18 2 0 R26 Area(km2) 69588 12837 338 0 % 29 5 0 0 R85 Area(km2) 79385 13512 338 0 % 33 6 0 0 High Current Area(km2) 105058 44591 5405 0 % 44 19 2 0 R26 Area(km2) 107761 57427 20268 3040 % 45 24 8 1 R85 Area(km2) 104045 60130 18917 3378 % 44 25 8 1 Low Current Area(km2) 89519 65197 21958 1689 % 37 27 9 1 R26 Area(km2) 87492 77696 39861 7770 % 37 32 17 3 R85 Area(km2) 62832 62494 40875 3040 % 26 26 17 1 Very low Current Area(km2) 74318 59792 13175 1351 % 31 25 6 1 R26 Area(km2) 61143 38510 3716 3716 % 26 16 2 2 R85 Area(km2) 77696 29389 14188 0 % 32 12 6 0 https://doi.org/10.1371/journal.pone.0229881.t005 PLOS ONE Climate change and food crops suitability in Ghana PLOS ONE | https://doi.org/10.1371/journal.pone.0229881 June 29, 2020 13 / 21