Projected changes in tropical cyclones over the South West Indian Ocean under different extents of global

Abstract

The Paris Agreement achieved in December 2015 established that the signatory countries should pursue to hold the increase in global average temperature to below 2°C relative to the preindustrial period and to strive to limit the temperature increase to 1.5°C below the preindustrial period. The potential changes in tropical cyclones over the basin making landfall over southern Africa under the key global temperature goals, have not been thoroughly investigated. Using the Coordinated Regional Downscaling Experiment-Africa (CORDEX) regional climate models, we downscale six global climate models of the Coupled Model Inter-comparison Project Phase 5 (CMIP5) to high resolution. This serves towards studying changes in tropical cyclone tracks over the South West Indian Ocean under different extents of global warming (1.5, 2 and 3° C of warming with respect to pre-industrial conditions). It is projected that the number of tropical cyclones making landfalls over southern Africa under global warming will decrease, with 2 °C being a critical threshold, after which the rate of cyclone frequency with further temperature increases no longer has a diminishing effect. Fewer cyclones may bring benefits and reduce damage to the southern African region. Although a decrease in damages associated with flood events is desirable, general decreases in tropical cyclone and tropical lows may also be associated with decreased rainfall over the Limpopo River basin and southern, central and northern Mozambique (with negative impacts on dryland agriculture).