As Madagascar, Malawi and Mozambique mop up after Cyclone Ana, scientists caution that South Africa’s east coast could be hit by intense tropical cyclones.

Over the past week, the first seasonal cyclone in the Southwest Indian Ocean killed at least 34 people in Madagascar and two in Mozambique, and left large swathes of Malawi without power. 

While authorities in the affected countries focus on counting the cost and responding to the devastation, the storm — Ana — serves as a brutal reminder of the vulnerability of communities in the developing world and the future risks that South Africa will have to navigate as the level of global warming increases.

The United Nations Office for the Coordination of Humanitarian Affairs explained that: “A low-pressure system formed in the south-west part of the Indian Ocean over the past days, crossing over Madagascar on 22 January. The system entered the Mozambique channel on 23 January and evolved into a moderate tropical storm… making landfall in Nampula province on 24 January. Tropical storm Ana, whose force has already been perceived in some provinces, could cause wind speeds up to 100km/h and rains up to 200mm/24h.”

On Wednesday, Unicef elaborated on the destruction wrought and its attendant impacts, saying that, “Strong winds and heavy rainfall caused by Tropical Storm Ana have disrupted the lives of thousands of children in four countries in Eastern and Southern Africa.

“The situation in some locations remains dire for children and families on the ground, with rains still coming, and water levels rising. The tropical storm sheds a light again on the risks and consequences of climate emergencies in the region, as well as the need for immediate humanitarian assistance from the onset — including in the most remote areas where access is difficult.”

Unicef’s statement continued that, “In Mozambique, where insecurity continues to negatively impact on child nutrition, the recent tropical storm adds one more crisis for too many children. Right now, an estimated 21,000 people have been affected by the cyclone, many of them children. In addition, at least 77 classrooms and six health centres have been partially or completely destroyed, leaving 2,000 students out of school and communities without access to health services.”

Landry Ninteretse, regional director at 350Africa.org, said: “As a climate justice organisation, we are concerned about the impact of this tropical cyclone, more so in these vulnerable areas that are yet to recover from devastating climate disasters they have experienced.

“We stand in solidarity with our comrades and partners affected by this disaster and call on humanitarian agencies to move with speed to save lives. Needless to say, disasters such as these are further evidence of the injustice suffered by the nations that contribute least to the climate crisis, as they bear the brunt of the crisis, by way of worsening climate impacts.

“Not only should this be a wake-up call for the biggest polluters to commit to plans to significantly lower greenhouse gas emissions by moving away from fossil fuels, but also for the developed world to make good on its promise of climate finance to help vulnerable nations deal with the impacts of the climate crisis.” 

The news of Ana’s deadly path comes on the heels of the publication of a recent, groundbreaking study in the journal Nature Geoscience led by scientists at the University of KwaZulu-Natal (UKZN), which has bolstered arguments that increased levels of global warming and warmer oceans could lead to cyclones making landfall on South Africa’s east coast in the future.

Using state-of-the-art techniques to investigate seabed sediments, the study revealed that severe tropical cyclones had made landfall on the eastern coast of South Africa in the past and that under projected climate change conditions these damaging phenomena could arise again in the future. 

The team, consisting of geologists from a number of countries including Germany and the UK, examined the sediment record from the seabed off the coast of Durban and found that there was a period — under higher sea levels — when storms were much more extreme than they are now.

“We found distinctive sediments that were deposited by severe storms that struck the coast between approximately 5,000 and 7,000 years ago,” said Professor Andrew Green, head of the Marine Geology Research Unit at UKZN, who led the research. 

“These storms were much bigger than any storm that happened in the 4,000 years since. This has allowed the storm sediments, or tempestites, to be preserved just beneath the seabed.”

This period of increased tempestuousness coincided with warmer sea temperatures in the Indian Ocean, which allowed tropical storms to travel further south than they do presently. 

Dr Carlos Loureiro, lecturer in physical geography at the University of Stirling in Scotland, carried out modelling of the storm waves and analysed how current ocean trends and climate projections aligned with past climate conditions.

“This important work demonstrates that the past climate conditions that allowed very intense tropical cyclones to reach the South African coast are very similar to the ones projected now under climate change,” said Loureiro.

“By confirming that these conditions existed in the past, our work provides strong support to recent climate modelling studies indicating that tropical cyclones are likely to migrate poleward in response to global warming.”

At present, tropical storms in the region are usually confined to central Mozambique, but renewed ocean warming because of climate change could once again allow them to travel south, with potentially disastrous implications for cities like Maputo, Durban and Richards Bay.

“When these storms hit the coast there were no cities, buildings or roads, and the coastline was free to adjust in a natural manner,” said Honorary Research Professor Andrew Cooper, a fellow of the Royal Society.

“If such a storm were to happen now, beachfront infrastructure would be devastated and the rainfall associated with tropical cyclones would cause serious flooding.”

This research gives impetus to the need to evaluate hazards along South Africa’s east coast that will be more vulnerable to tropical cyclones making landfall. It also added additional scientific weight to the assessment of climatologists at the Global Change Institute at the University of the Witwatersrand.  

After the release of the most recent “code red for humanity” IPCC report in August 2021, Professor Francois Engelbrecht, a leading climatologist and director at the Global Change Institute, told Daily Maverick that, “The climate science is clear that as the environment warms, these tropical cyclones can survive further south and that is why this is a risk. 

“South Africa is not prepared for the possibility of an intense tropical cyclone moving southwards where it can maybe impact Maputo and move over the Limpopo River Valley.”  

As noted above, tropical cyclones seldom make landfall in South Africa. The last recorded case is that of Cyclone Domoina, which in 1984 caused record floods.

“In terms of its intensity, today it would, strictly speaking, not meet the technical category of a Category One hurricane, yet it was terribly devastating. The point is that these tropical cyclones just don’t reach South Africa, but when one did reach us it caused widespread flooding and tens of people died in South Africa,” said Engelbrecht.

Now, because of global warming, there is much more energy available for tropical cyclones to become intense.

“My analysis is, and the assessment of the Global Change Institute is, that the risks exist for such an intense tropical cyclone to make landfall in South Africa. It will bring complete chaos and destruction as we’ve never seen before. We will not know what to do when such a cyclone strikes Richards Bay or if it strikes Maputo and then moves westward along the Limpopo River Valley or along the boundary of SA and Zimbabwe.

“The point is that northeastern South Africa is, for the first time in recorded history, at risk of a Category Three to Category Five hurricane making landfall. The flooding will be enormous. The risk to life will be tremendous for communities living near the rivers in the northeast. We will not be used to 200km/h winds and vulnerable people in informal settlements will have their roofs and walls ripped off.”