/ 20 July 2023

Wits co-leads initiative to mitigate effects of tropical cyclones

Cyclone Idai's devastation of Beira.
Cyclone Idai's devastation of Beira.

At midnight on 14 March 2019, Cyclone Idai tore into Beira, Mozambique, with catastrophic force, killing more than 1 500 people. 

For climatology professor Francois Engelbrecht, the devastation it wrought was the “final straw” that has led to a first-of-its kind initiative to fight the effect of tropical cyclones on the region. 

The pioneering R110 million project, co-led by the University of the Witwatersrand’s Global Change Institute (GCI), where Engelbrecht is the director, aims to improve early warnings and improve resilience to changing tropical cyclones in Southern Africa and Madagascar. 

“There is a big consortium of 11 organisations and we all came together and we said science needs to respond to this challenge.” 

That more than 1 500 people lost their lives in the path of Cyclone Idai is shocking, he said. “This makes Idai by far the worst flood disaster in the history of Africa south of the equator and the worst tropical cyclone disaster ever in Africa.” 

Then, in February this year, the record-breaking Tropical Cyclone Freddy slammed into Mozambique and Malawi, leaving 1 400 people dead. 

“Now, we had these two cyclones in four years that, for the first time, killed more than 1 000 people in Southern Africa. This has never happened before, that so many people died.”

He said there is clear evidence that these systems are becoming more intense across the world and our region is no exception, highlighting the need for such surveillance.

Killing more people

Tropical cyclones are becoming more powerful in the southwest Indian Ocean and in the Mozambique Channel. And, they are killing more people because of this. Specifically, this is because they unleash more rainfall than they did in the past, Engelbrecht explained.

In a warmer world, the tropical oceans are also warmer, there’s more evaporation into the atmosphere and, consequently, there’s more water vapour available to form clouds and to cause heavy precipitation. 

Against this background, the interdisciplinary team of scientists have come together in Resilience and Preparedness to Tropical Cyclones Across Southern Africa (Represa), an international collaborative effort involving partners across Southern Africa, the UK and Europe. 

The groundbreaking project is co-led by the GCI, Eduardo Mondlane University in Mozambique and the University of Bristol in the UK. It is part of the Climate Adaptation and Resilience (Clare) research initiative, a UK-Canada framework research programme on climate adaptation and resilience. 

The Represa project runs from June this year until November 2026 and is a “true north-south partnership”, said Lizzie Kendon, professor of climate science at the University of Bristol Cabot Institute for the Environment. While Southern Africa is hugely vulnerable to tropical cyclones, “we know very little about how tropical cyclones are changing in the region under a warming climate”.

Represa will bring together state-of-the-art climate and flood modelling to make a real difference to people’s lives in some of the most vulnerable communities, including women and children displaced by conflict, Kendon said.

Changing track

Effectively, Engelbrecht said, there are four things they want to do. “The first is we can talk generally about how the cyclones will change but we need specifics, so that we can plan [and] adapt in a changing climate.”  

One of the biggest questions is whether there will be a shift in the tracks of tropical cyclones. “We know they are getting more intense but can it happen that a cyclone such as the one that hit Beira — Idai — which was a category four [category five being the worst] hurricane in the Mozambique Channel just before it made landfall, is it possible that such a system hits Maputo? Can they move that far south for the first time?” 

In Maputo, this would be disastrous because those living in its informal settlements have no experience of dealing with such a system, while the economic effect on Mozambique would be devastating. This risk needs to be quantified.

“Is it possible that such a system can make a direct hit at Richards Bay?” asked Engelbrecht. “If a Category three to five hurricane moves that far south, we’ll be in deep trouble in Richards Bay as well. 

“Now, in between Richards Bay and Maputo, such a system can also move into the Limpopo River Valley, between South Africa and Zimbabwe, which will also be catastrophic. Or it can hit the Mpumalanga Lowveld so South Africa and the northeast is also vulnerable and southern Mozambique is even more exposed to this possibility.”

Climate modelling

The project will use the most sophisticated climate modelling effort ever undertaken for this part of the world to quantify the risk of changes in these systems, Engelbrecht said. 

“We will use our African-based climate model at the GCI — the only one in Africa — and we will use the climate model of the UK Met Office. Both will run on supercomputers, in our case under a supercomputer of the Centre for High Performance Computing in South Africa [of] the department of science and innovation computer cluster, and the British will use their computer.”

Never before have climate models been integrated at such fine spatial scales for this region. “This means that we can simulate the cyclones more realistically than ever before, for example, the eyewall that forms around a storm.”

This will give the team a chance of generating reliable projections of changes in these systems for the region, he said.

Storm surges

Another key component is hydrological modelling of river flows and storm surges, in conjunction with climate modelling. 

“What happens to the rivers around Beira, for example, when a cyclone makes landfall? …Then it’s also the storm surge, that wall of seawater that forms around the centre of a low before it makes landfall. We also want to understand how this will change.

“Is Maputo at risk of a storm surge? Is Richards Bay at risk? Is it possible that a category five can make landfall in Beira, with a massive storm surge that can potentially kill thousands of people?” 

The UK Met Office and the European Centre for Medium-Range Weather Forecasts will combine their strengths with weather services in Malawi, Mozambique and Madagascar. Jointly, they will develop improved weather forecast systems in terms of tropical cyclone landfalls and intensity predictions as well as predictions of storm surges and strong winds. 


The second component is about short-range forecasting, “so when there is a system in the Mozambique Channel, where will it make landfall? We are going to improve this capability in Southern Africa, which gives us the ability to warn people.”

This is the “spearpoint” of the project. “You can generate the best forecast but if there’s no uptake of the forecast, people can die. It’s not that we are bad with these short-range forecasts, but they can be improved and that’s what we want to do.” 

In the case of Idai, it was predicted three days ahead that its landfill would be at Beira.

“When the system reached Beira, thousands of the most vulnerable people were still where they always are — in the informal settlements. We need to understand why people are not always responding to the warnings.”

He questioned whether people trusted authorities and the forecasts they were getting or are they “worried about their livelihoods, their property, looting or do they have religious convictions”.

Robust climate adaptation strategies

Citing the deadly Durban floods in April last year, caused by a cut-off low and not a tropical cyclone, Engelbrecht said Southern Africa needs to be better at evacuating people out of the path of danger.

“Forty thousand people were displaced in Durban by the floods — forcefully. Why didn’t we just evacuate the 5 000 most vulnerable, the day before the floods, and save 540 lives? We have to develop systems and a culture of evacuating the most vulnerable.”

Nor should there be an acceptance that people in the region will always be so vulnerable. “So, while they are, we must try to help them with the early warning and its uptake but, in the long run, we must develop adaptation interventions to make people less vulnerable.”