Climatic suitability predictions for the cultivation of macadamia in Malawi using climate change scenarios.

Abstract

Global climate change is altering the suitable areas of crop species worldwide, with cascading effects on people and animals reliant upon those crop species as food sources. Macadamia is one of these essential lucrative crop species that grows in Malawi. Here, we used an ensemble model approach to determine the current distribution of macadamia production areas across Malawi in relation to climate. For future distribution of suitable areas, we used the climate outputs of 17 general circulation models based on two climate change scenarios (RCP 4.5 and RCP 8.5). The precipitation of the driest month and isothermality were the climatic variables that strongly influenced macadamias suitability in Malawi. We found that these climatic requirements were fulfilled across many areas in Malawi under the current conditions. Future projections indicated that vast parts of Malawis macadamia growing regions will remain suitable for macadamia, amounting to 36,910 km2 (39.1%) and 33,511 km2 (35.5%) of land based on RCP 4.5 and RCP 8.5, respectively. Alarmingly, suitable areas for macadamia production are predicted to shrink by -18% (17,015 km2) and -21.6% (20,414 km2) based on RCP 4.5 and RCP 8.5, respectively, with much of the suitability shifting northwards. This means that some currently productive areas will become unproductive in the future, while current unproductive areas will become productive. Notably, suitable areas will increase in Malawis central and northern highlands, while the southern region will lose most of its suitable areas. Our study, therefore, shows that there is potential for expanding macadamia production in Malawi. Most, importantly our future projections provide critical evidence on the potential negative impacts of climate change on the suitability of macadamia production in the country. We recommend developing area-specific adaptation strategies to build resilience in the macadamia sector in Malawi under climate change.