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.