Investigating the potential impact of 1.5, 2 and 3 °C global warming levels on crop suitability and planting season over West Africa

Temitope Samuel Egbebiyi; Olivier Crespo; Christopher Lennard; Modathir Zaroug; Grigory Nikulin; Ian Harris; Jeff Price; Nicole Forstenhäusler; Rachel Warren

doi:10.7717/peerj.8851

Investigating the potential impact of 1.5, 2 and 3 °C global warming levels on crop suitability and planting season over West Africa

PeerJ. 2020 May 5:8:e8851. doi: 10.7717/peerj.8851. eCollection 2020.

Authors

Affiliations

¹ Climate System Analysis Group (CSAG), Department of Environmental and Geographical Science, University of Cape Town, Cape Town, Western Cape, South Africa.
² African Climate and Development Initiative (ACDI), University of Cape Town, South Africa.
³ Nile Basin Initiative Secretariat, Entebbe, Uganda.
⁴ Swedish Meteorological and Hydrological Institute, Norrköping, Sweden.
⁵ Climate Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom.
⁶ Tyndall Centre for Climate Change Research, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom.

Abstract

West African rainfed agriculture is highly vulnerable to climate variability and change. Global warming is projected to result in higher regional warming and have a strong impact on agriculture. This study specifically examines the impact of global warming levels (GWLs) of 1.5°, 2° and 3 °C relative to 1971-2000 on crop suitability over West Africa. We used 10 Coupled Model Intercomparison Project Phase5 Global Climate Models (CMIP5 GCMs) downscaled by Coordinated Regional Downscaling Experiment (CORDEX) Rossby Centre's regional Atmospheric model version 4, RCA4, to drive Ecocrop, a crop suitability model, for pearl millet, cassava, groundnut, cowpea, maize and plantain. The results show Ecocrop simulated crop suitability spatial representation with higher suitability, observed to the south of latitude 14°N and lower suitability to its north for 1971-2000 for all crops except for plantain (12°N). The model also simulates the best three planting months within the growing season from September-August over the past climate. Projected changes in crop suitability under the three GWLs 1.5-3.0 °C suggest a spatial suitability expansion for legume and cereal crops, notably in the central southern Sahel zone; root and tuber and plantain in the central Guinea-Savanna zone. In contrast, projected decreases in the crop suitability index value are predicted to the south of 14°N for cereals, root and tuber crops; nevertheless, the areas remain suitable for the crops. A delay of between 1-3 months is projected over the region during the planting month under the three GWLs for legumes, pearl millet and plantain. A two month delay in planting is projected in the south, notably over the Guinea and central Savanna zone with earlier planting of about three months in the Savanna-Sahel zones. The effect of GWL2.0 and GWL3.0 warming in comparison to GWL1.5 °C are more dramatic on cereals and root and tuber crops, especially cassava. All the projected changes in simulated crop suitability in response to climatic variables are statistically significant at 99% confidence level. There is also an increasing trend in the projected crop suitability change across the three warming except for cowpea. This study has implications for improving the resilience of crop production to climate changes, and more broadly, to food security in West Africa.

Keywords: CORDEX; Crop suitability; Ecocrop; Food security; Global warming levels, 1.5, 2.0 & 3.0 °C; Planting season; West Africa.

Grants and funding

This research was supported by funding from the National Research Foundation (NRF, South Africa). the Tyndall Centre for Climate Change and Climatic Research Unit (CRU) under the Newton PhD Partnering Scheme funded by Research Councils United Kingdom (RCUK), the Alliance Centre for Climate and Earth Systems Science (ACCESS, South Africa), the African Climate and Development Initiative (ACDI), the JW Jagger Centenary Scholarship and the Siri Johnson scholarship, University of Cape Town, South Africa. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.