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Landscape change studies bring better understanding of climate change

03 November 2022 | Story Leonie Bolleurs | Photo Supplied

A study of subantarctic islands tells us that, in general, the Southern Hemisphere is experiencing a rise in temperature, with an increase in rainfall in some locations, and other areas becoming drier. The annual temperature and rainfall average remain the same in some places, but there is a change in seasonality and synoptic weather events.

This is according to Dr Liezel Rudolph, a lecturer in the Department of Geography at the University of the Free State (UFS). She recently returned from an expedition to Gough Island in the South Atlantic Ocean, supported by the South African National Department of Forestry, Fisheries and the Environment, the National Research Foundation, and the Royal Society for the Protection of Birds.

This teacher of modules on Process Geomorphology and fieldwork techniques at the UFS, says the objective of her work on the island was to do a geomorphological survey of the island and explore the suitability of geochronological dating techniques on the island’s substrate.

She explains that with geochronological methods one can determine the age of rock material as well as the rate of landscape change on the island. “In other words, dating when the volcano was formed and determining how long it takes for weathering to break down the rock material, and erosional processes to remove soil material.”

The research she is involved in, forms part of a SANAP-NRF-funded project, Sub-Antarctic Landscape Climate Interactions, which aims to better understand the landscape evolution of some subantarctic Islands and their response to long-term climate change.

Studying the past to understand the present

According to her, studying landscape change enables one to better understand climate change over a long period of time.

She states that the more regions are investigated, the clearer the picture of climate change will become. “The Earth is a large, complex system. By studying climate change in one location, one cannot simply assume that the same type and rate of change is occurring everywhere else. It would be like imaging a 1 000-piece puzzle by building with 10 pieces. The Southern Hemisphere is predominantly ocean, which makes it difficult to pin down land-atmosphere interactions – but the subantarctic islands give us the opportunity to create data points for the Southern Hemisphere, which would otherwise be a very large missing piece of the puzzle,” explains Dr Rudolph.

She says the interaction between ocean, atmosphere, and land remains complex and it is important to study the entire picture in order to fully understand how this is happening. Especially since the climate is changing at a drastic rate.

Dr Rudolph, whose research at the UFS is focused on constraining the last glaciation of subantarctic Marion Island though various proxies and dating techniques, says the subantarctic islands are very sensitive to changes in climate.

A clearer picture of climate change

She was part of previous expeditions to the island. Although all these expeditions had different goals, according to her, they all aimed to answer the same questions, which are how the island’s landscape has developed throughout history and what the climatic drivers were during its evolution.

“The landscape responds to changes in temperature and precipitation. Under colder, wetter conditions – when the island’s surface is subject to a freeze-thaw process – a range of peri-glacial landforms will develop. These landforms will still be evident in the landscape years later under a different climate, for example, warmer or drier conditions. We can study these landforms in real-time and establish whether they are actively forming or are relict features that formed under different climatic environments,” remarks Dr Rudolph.

The research, which is taking place in collaboration with the British Antarctic Survey, is co-led by Prof Werner Nel from the University of Fort Hare, and Prof David Hedding from the University of South Africa.

• Dr Rudolph is grateful to the Government of Tristan da Cunha, which is responsible for managing the conservation of Gough Island, for permitting them to do scientific work on the island.

News Archive

Fight against Ebola virus requires more research

2014-10-22

Dr Abdon Atangana
Photo: Ifa Tshishonge

Dr Abdon Atangana, a postdoctoral researcher in the Institute for Groundwater Studies at the University of the Free State (UFS), wrote an article related to the Ebola virus: Modelling the Ebola haemorrhagic fever with the beta-derivative: Deathly infection disease in West African countries.

“The filoviruses belong to a virus family named filoviridae. This virus can cause unembellished haemorrhagic fever in humans and nonhuman monkeys. In literature, only two members of this virus family have been mentioned, namely the Marburg virus and the Ebola virus. However, so far only five species of the Ebola virus have been identified, including: Ivory Coast, Sudan, Zaire, Reston and Bundibugyo.

“Among these families, the Ebola virus is the only member of the Zaire Ebola virus species and also the most dangerous, being responsible for the largest number of outbreaks.

“Ebola is an unusual, but fatal virus that causes bleeding inside and outside the body. As the virus spreads through the body, it damages the immune system and organs. Ultimately, it causes the blood-clotting levels in cells to drop. This leads to severe, uncontrollable bleeding.

Since all physical problems can be modelled via mathematical equation, Dr Atangana aimed in his research (the paper was published in BioMed Research International with impact factor 2.701) to analyse the spread of this deadly disease using mathematical equations. We shall propose a model underpinning the spread of this disease in a given Sub-Saharan African country,” he said.

The mathematical equations are used to predict the future behaviour of the disease, especially the spread of the disease among the targeted population. These mathematical equations are called differential equation and are only using the concept of rate of change over time.

However, there is several definitions for derivative, and the choice of the derivative used for such a model is very important, because the more accurate the model, the better results will be obtained. The classical derivative describes the change of rate, but it is an approximation of the real velocity of the object under study. The beta derivative is the modification of the classical derivative that takes into account the time scale and also has a new parameter that can be considered as the fractional order.

“I have used the beta derivative to model the spread of the fatal disease called Ebola, which has killed many people in the West African countries, including Nigeria, Sierra Leone, Guinea and Liberia, since December 2013,” he said.

The constructed mathematical equations were called Atangana’s Beta Ebola System of Equations (ABESE). “We did the investigation of the stable endemic points and presented the Eigen-Values using the Jacobian method. The homotopy decomposition method was used to solve the resulted system of equations. The convergence of the method was presented and some numerical simulations were done for different values of beta.

“The simulations showed that our model is more realistic for all betas less than 0.5. The model revealed that, if there were no recovery precaution for a given population in a West African country, the entire population of that country would all die in a very short period of time, even if the total number of the infected population is very small. In simple terms, the prediction revealed a fast spread of the virus among the targeted population. These results can be used to educate and inform people about the rapid spread of the deadly disease,” he said.

The spread of Ebola among people only occurs through direct contact with the blood or body fluids of a person after symptoms have developed. Body fluid that may contain the Ebola virus includes saliva, mucus, vomit, faeces, sweat, tears, breast milk, urine and semen. Entry points include the nose, mouth, eyes, open wounds, cuts and abrasions. Note should be taken that contact with objects contaminated by the virus, particularly needles and syringes, may also transmit the infection.

“Based on the predictions in this paper, we are calling on more research regarding this disease; in particular, we are calling on researchers to pay attention to finding an efficient cure or more effective prevention, to reduce the risk of contamination,” Dr Atangana said.

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