Climate, migration and conflict mix to create ‘deadly’ intense tropical storms like Chido

Cyclone Chido was an “intense tropical cyclone”, equivalent to a category 4 hurricane in the Atlantic. It made landfall in Mayotte, a small island lying to the north-west of Madagascar on December 14, generating wind gusts approaching 155mph (250km/hr). Later on, it hit Mozambique, East Africa with the same ferocity.

This storm skirted north of Madagascar and affected the Comoros archipelago before making landfall in Mozambique. It is well within the range of what is expected for this part of the Indian Ocean. But this region has experienced an increase in the most intense tropical cyclones in recent years. This, alongside its occurrence so early in the season, can be linked to increases in ocean temperatures as a result of climate change.

News of the effects of tropical cyclone Chido in Mayotte, Mozambique and Malawi continues to emerge. Current estimates suggest 70% of Mayotte’s population have been affected, with over 50,000 homes in Mozambique partially or completely destroyed.

Ongoing conflict in Mozambique and undocumented migration to Mayotte will have played a key role in the number of deaths and the infrastructure damage.

Assessing how these cyclones characteristics are changing across southern Africa is part of the research we are involved in. Our team also studies how to build resilience to cyclones where conflict, displacement and migration magnify their effects.

A human-made disaster?

The risk that tropical cyclones pose to human life is exacerbated by socioeconomic issues. Migrants on Mayotte, many of whom made perilous journeys to escape conflict in countries such as the Democratic Republic of Congo, now make up more than half of the island’s population.

Precarious housing and the undocumented status of many residents reportedly made the disaster more deadly, as people feared evacuation would lead them to the police. On islands with poor infrastructure such as Mayotte, there is often simply nowhere safe to go. It takes many days for the power network and drinking water supply to be restored.

The situation is particularly complex in Mozambique. The ongoing conflict and terrorist violence, coupled with cyclones, including Kenneth in 2019, has caused repeated evacuations and worsening living conditions. Cabo Delgado and Nampula in the far north of Mozambique, the provinces most affected by both Chido and the conflict, rank among the poorest and most densely populated in the country due to limited education, scarce livelihood options and an influx of people displaced by violence.

As of June 2024, more than half a million people remained without permanent homes in the region, many living in displacement camps. That number is likely to rise significantly after Chido.

Compounding the crisis, Chido’s landfall so early in the cyclone season meant that the usual technical and financial preparations were not yet fully ramped up, with low stock levels delaying the timely delivery of aid. Unrest following elections in November hampered preparations further, cutting the flow of resources and personnel needed for anticipatory action and early response.

Tropical cyclones in a warmer world

Warmer sea surface temperatures not only provide more fuel for stronger storms, but may also expand the regions at risk of tropical cyclones.

The Indian Ocean is warming faster than the global average, and is experiencing a staggering increase in the proportion of storms reaching the intensity of Chido.

Climate simulations predict that storms will continue getting stronger as we further warm our world, and could even lead to an unprecedented landfall as far south as the Mozambican capital, Maputo.

Scientists carry out attribution studies to determine how climate change contributed to specific events. Scientists undertaking rapid attribution studies of Chido have found that the ocean surface temperatures along the path of the storm were 1.1°C warmer than they would have been without climate change. So, temperatures this warm were made more than 50 times more likely by climate change. Another study focusing on Chido itself concluded that the cyclone’s winds were 5% faster due to global heating caused by burning fossil fuels, enough to bump it from a category 3 to a category 4 storm.

Intense winds are not the only hazard. Scientists are confident that tropical cyclones will dump more rain as a result of climate change. A trend towards slower-moving storms has been observed, causing more of that rain to accumulate in a single location, resulting in floods.

Cyclone Freddy delivered a year’s worth of rain to southern Malawi in just four days in March 2023. Storm surges, exacerbated by sea level rise, also raise the scale of flooding, as in the devastating Cyclone Idai in March 2019. An increase in the number of storms that rapidly intensify, as Chido did before landfall in Mayotte has also been linked to climate change, which makes it harder to provide early warnings.

To improve resilience to future cyclones, conflict, migration and social dynamics must be considered alongside climate change, without this, displaced and migrant communities will continue to be the most affected by the risks that climate change poses.

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Liz Stephens also works for the Red Cross Red Crescent Climate Centre, where she works as the Science Lead. She receives funding from the Foreign, Commonwealth & Development Office (FCDO) and the International Development Research Centre in Canada, as part of the CLARE (CLimate Adaptation and REsilience) research programme. Liz holds advisory positions within the Red Cross Red Crescent Movement, for the European Commission's Global Flood Awareness System, the Anticipation Hub and the African Risk Capacity

I work for a university which has interest on publications around disasters and climate change. I am part of a research consortium (REPRESA) funded by IDRC to research cyclones in Southern Africa region

Dan Green does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.