Preprints
https://doi.org/10.5194/egusphere-2023-1712
https://doi.org/10.5194/egusphere-2023-1712
27 Jul 2023
 | 27 Jul 2023

The perfect storm? Concurrent climate extremes in East Africa

Derrick Muheki, Axel Antonius Johannes Deijns, Emanuele Bevacqua, Gabriele Messori, Jakob Zscheischler, and Wim Thiery

Abstract. Concurrent extreme climate events exacerbate adverse impacts on humans, the economy, and the environment relative to extremes occurring in isolation. While changes in the frequency of individual extreme events have been researched extensively, changes in their interactions, dependence and joint occurrence have received far less attention, particularly in the East African region. Here, we analyse the joint occurrence of pairs of the following extremes over East Africa: river floods, droughts, heatwaves, crop failures, wildfires and tropical cyclones. We use bias-adjusted impact simulations under past and future climate conditions from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). We find an increase in the area affected by pairs of these extreme events, with the strongest increases for joint heatwaves & wildfires (+940 % by the end of the century under RCP6.0 relative to present day), followed by river floods & heatwaves (+900 %) and river floods & wildfires (+250 %). The projected increase in joint occurrences typically outweighs historical increases even under an aggressive mitigation scenario (RCP2.6). We illustrate that the changes in the joint occurrences are often driven by increases in the probability of one of the events within the pairs, for instance heatwaves. The most affected locations in the East Africa region by these concurrent events are areas close to the River Nile and parts of the Congo basin. Our results overall highlight that concurrent extremes will become the norm rather than the exception in East Africa, even under low-end warming scenarios.

Derrick Muheki, Axel Antonius Johannes Deijns, Emanuele Bevacqua, Gabriele Messori, Jakob Zscheischler, and Wim Thiery

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1712', Anonymous Referee #1, 29 Aug 2023
    • AC1: 'Reply on RC1', Derrick Muheki, 06 Sep 2023
  • RC2: 'Comment on egusphere-2023-1712', Anonymous Referee #2, 10 Sep 2023
    • AC2: 'Reply on RC2', Derrick Muheki, 07 Oct 2023
Derrick Muheki, Axel Antonius Johannes Deijns, Emanuele Bevacqua, Gabriele Messori, Jakob Zscheischler, and Wim Thiery

Data sets

Postprocessed ISIMIP2b simulation output Lange et al. (2020 Earth's Future) and Thiery et al. (2021 Science) https://doi.org/10.5281/zenodo.5497633

Model code and software

concurrent_climate_extremes_in_east_africa Derrick Muheki, Axel A. J. Deijns, Emanuele Bevacqua, Gabriele Messori, Jakob Zscheischler, Wim Thiery https://github.com/VUB-HYDR/concurrent_climate_extremes_in_east_africa

Derrick Muheki, Axel Antonius Johannes Deijns, Emanuele Bevacqua, Gabriele Messori, Jakob Zscheischler, and Wim Thiery

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Latest update: 01 Mar 2024
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Extremes are of utmost importance due to their impacts on life and livelihoods or people. Also Africa is a relatively less studied region but where people are also strongly affected by extremes and thus are very vulnerable. This study uses a systematic approach to examine concurrent extremes.
Short summary
Climate change affects the interaction, dependence, and joint occurrence of climate extremes. Here we investigate the joint occurrence of pairs of river floods, droughts, heatwaves, crop failures, wildfires, and tropical cyclones over East Africa, under past and future climate conditions. Our results show that, across all warming scenarios, the frequency and spatial extent of these co-occurring extremes will increase in this region, particularly in areas close to the Nile and Congo rivers.