Mientras el mar avanza sobre el litoral sudafricano, una fuerza natural efecto del cambio climático emerge: la sequía. Investigaciones recientes indican que ciertas áreas de la nación están experimentando una lenta elevación sobre el nivel del mar, causada por la disminución del agua subterránea.
La subida del nivel del mar representa una amenaza para las costas de Sudáfrica, golpeando a las ciudades con erosión e inundaciones. No obstante, en lo que constituye un giro inesperado para la climatología, el suelo bajo algunas regiones del país parece estar en proceso de elevación.
Científicos de Alemania postulan que la aridez y la subsecuente pérdida de agua, derivadas del calentamiento global, podrían ser la causa de que secciones de Sudáfrica se eleven anualmente dos milímetros por encima del nivel del mar.
South African coastal cities, such as Cape Town, Durban and Port Elizabeth, are suffering the consequences of coastal erosion, recurrent flooding and the destruction of natural habitats and essential infrastructure.
In 2017, the nation also experienced a series of extreme weather events: large waves, storm surges, heavy rains, wildfires and hurricane-force winds that ravaged the southwestern cape.
These storms caused at least eight deaths and affected 135 schools. Nearly 800 homes in Cape Town ended up flooded.
These incidents highlight the growing dangers faced by South Africa’s coastal areas due to the increase in extreme weather phenomena. Scientists claim that these events will become more frequent and intense due to rising global temperatures.
David Willima, who researches ocean governance policies in South Africa, noted that it is crucial to merge concerns about the climate and the oceans in the political realm to effectively address the threat of rising sea levels.
“The difficulty lies in that South Africa has not succeeded in successfully connecting climate and ocean discussions; they are often handled as independent topics,” expressed Willima.
The continent rises due to climate change
As the dangers associated with the rise in sea levels grow, experts have detected that sections of South Africa’s coastal areas are experiencing a gradual elevation.
Traditionally, variations in ground elevation have been explained by deep geological processes, such as the displacement of hot materials beneath the earth’s crust.
However, recent research led by geodesist Makan Karegar from the University of Bonn questions that perspective.
The study points to droughts as the predominant causal factor as an effect of climate change.
“Subsurface water adds weight to the terrain,” Karegar explained to DW. “Abundant rainfall and flooding apply pressure on the earth’s crust on the surface, and that weight causes it to sink.”
During periods of drought, as water in the soil and aquifers decreases, the terrain loses weight and can rise, similar to how a sponge expands when it dries.
The research team used GPS measurements, satellite information and hydrological models to analyze the correlation between areas suffering severe droughts and a notable elevation of the terrain.
Jasper Knight, a geoscientist at the University of Witwatersrand in Johannesburg not involved in the study, believes the research is scientifically solid.
“They used high quality data and robust modeling techniques, and it’s interesting how they are applying it to the southern Africa context,” Knight commented.
“They suggest that climate variability is a significant driver of systematic variations in surface elevation across the area, contrasting with the traditional notion of tectonic uplift,” he added.
Is this a glimmer of hope?
Although this phenomenon could be interpreted as a natural defense against rising sea levels, Knight warns about the danger of reaching overly optimistic conclusions.
“Obviously, one could argue that if the terrain rises, then, in relative terms, the sea level could remain stable or even decrease,” Knight noted.
“However, this could occur at the expense of less water availability on the continent. In that dilemma, if I had to choose between a reduction in the rise of sea levels on the coast or drought inland, I would consider the sea level issue as the lesser evil,” he explained.
Karegar adds that, unlike some countries that artificially increase terrain elevation by injecting wastewater into the subsurface to mitigate the risk of flooding, South Africa’s case is the result of a natural drought.
Despite this, he maintained that the study’s findings have the potential to contribute to broader environmental management.
“These discoveries could be useful for optimizing the monitoring of droughts and floods, guiding the management of groundwater and underpinning more strategic planning of water resources, as well as climate change adaptation initiatives,” he concluded.
