09 Jan 2023
09 Jan 2023
Status: this preprint is open for discussion.

Human displacements from tropical cyclone Idai attributable to climate change

Benedikt Mester1,2, Thomas Vogt1, Seth Bryant2,3, Christian Otto1, Katja Frieler1, and Jacob Schewe1 Benedikt Mester et al.
  • 1Potsdam Institute for Climate Impact Research, Potsdam, Germany
  • 2Institute of Environmental Science and Geography, University of Potsdam, Potsdam, Germany
  • 3GFZ German Research Centre for Geosciences, Potsdam, Germany

Abstract. Extreme weather events often trigger massive population displacement. A compounding factor is that the frequency and intensity of such events is affected by anthropogenic climate change. However, the effect of historical climate change on displacement risk has so far not been quantified. Here, we show how displacement can be partially attributed to climate change, using the example of the 2019 tropical cyclone Idai in Mozambique. We estimate the population exposed to flooding following Idai’s landfall, using a combination of storm surge modeling and flood depth estimation from remote sensing images, for factual (climate change) and counterfactual (no climate change) mean sea level and maximum wind speed conditions. We find that climate change has increased displacement risk from this event by approximately 3.1 to 3.5 %, corresponding to 16,000–17,000 additional displaced persons. Besides highlighting the significant effects on humanitarian conditions already imparted by climate change, our study provides a blueprint for event-based displacement attribution.

Benedikt Mester et al.

Status: open (until 20 Feb 2023)

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Benedikt Mester et al.

Benedikt Mester et al.


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Short summary
In 2019, cyclone Idai displaced more than 478,000 people in Mozambique. In our study, we use coastal flood modeling and satellite imagery to construct a counterfactual cyclone event without the effects of climate change. We show that 17,000 displacements can be attributed to sea level rise and the intensification of storm wind speeds due to global warming. Our impact attribution study is the first one on human displacement and one of very few for a low-income country.