Future supply and demand of net primary production in the Sahel

Abstract

Abstract. In the 21st century, climate change in combination with increasing demand, mainly from population growth, will exert greater pressure on the ecosystems of the Sahel to supply food and feed resources. The balance between supply and demand, defined as the annual biomass required for human consumption, serves as a key metric for quantifying basic resource shortfalls over broad regions.Here we apply an exploratory modelling framework to analyse the variations in the timing and geography of different NPP (net primary production) supply-demand scenarios, with distinct assumptions determining supply and demand, for the 21st century Sahel. We achieve this by coupling a simple NPP supply model forced with projections from four representative concentration pathways with a global, reduced-complexity demand model driven by socio-economic data and assumptions derived from five shared socio-economic pathways.For the scenario that deviates least from current socio-economic and climate trends, we find that per capita NPP begins to outstrip supply in the 2040s, while by 2050 half the countries in the Sahel experience NPP shortfalls. We also find that despite variations in the timing of the onset of NPP shortfalls, demand cannot consistently be met across the majority of scenarios. Moreover, large between-country variations are shown across the scenarios, in which by the year 2050 some countries consistently experience shortage or surplus, while others shift from surplus to shortage. At the local level (i.e. grid cell), hotspots of total NPP shortfall consistently occur in the same locations across all scenarios but vary in size and magnitude. These hotspots are linked to population density and high demand. For all scenarios, total simulated NPP supply doubles by 2050 but is outpaced by increasing demand due to a combination of population growth and the adoption of diets rich in animal products. Finally, variations in the timing of the onset and end of supply shortfalls stem from the assumptions that underpin the shared socio-economic pathways rather than the representative concentration pathways.Our results suggest that the UN sustainable development goals for eradicating hunger are at high risk for failure. This emphasizes the importance of policy interventions such as the implementation of sustainable and healthy diets, family planning, reducing yield gaps, and encouraging the transfer of resources to impoverished areas via trade relations.

Integrating Multimodal Ensemble and Spatiotemporal Analysis for Enhanced Climate Modelling in Nigeria

“…The UN climate risk assessment profile has also noted that the Sahel region is one of the most vulnerable to CC with the warming climate to lead to higher reduction in agricultural output in the region in comparison to the reductions of global outputs; a consequence of this will be to further put food security at risk. (Sallaba et al, 2017). Rainfall is not widely varied from the MK trend test.…”

Climatic and non-climatic vegetation cover changes in the rangelands of Africa

“…However, LPJ-GUESS has been shown to capture the interannual variability of the terrestrial uptake of CO2 at the global scale (Ahlström et al, 2015;Piao et al, 2013;Schurgers et al, 2018) and, more specifically, the interannual and decadal dynamics of biomass changes in Africa (Brandt et al, 2018(Brandt et al, , 2017Lehsten et al, 2009;Sallaba et al, 2017), both of which are primarily driven by climatic variations. This gives us confidence in using LPJ-GUESS as a tool to estimate expected climate-driven trends in this study.…”