Study of sub-Antarctic islands sheds more light on climate change

A study of the sub-Antarctic islands has given researchers better understanding of climate change, revealing a temperature rise in the southern hemisphere, while some locations experienced increased rain and others were drier.

Researchers have observed that, although annual temperature and average rainfall remain the same in some places, there was a change in seasonal sequence and common weather events.

University of the Free State geography lecturer Dr Liezel Rudolph said with geochronological methods, researchers were able to work out the age of rock material and the rate of landscape change on the islands.

The study forms part of a South African National Antarctic Programme-National Research Foundation-funded project, Sub-Antarctic Landscape Climate Interactions, which aims to better understand the landscape evolution of some sub-Antarctic islands and their response to long-term climate change.

The researchers’ ultimate goals is to understand how the island’s landscape has developed and what the climatic drivers were during its evolution.

Free from impact of human activity

According to Rudolph, these islands act as natural laboratories as they are largely free from impact of human activity.

The Prince Edward Islands, in particular, she said, were extremely important for SA, as it is one of few nations with territory in the Southern Ocean.

“It gives us a unique opportunity to contribute to global science.

“These two islands, Marion and Prince Edward, are some of the best conserved sub-Antarctic islands in the world, with Prince Edward Island still very close to its original, natural, pristine state,” she said.

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Studying landscape change, Rudolph explained, enabled researchers to better understand climate change over a long period of time and the more regions that were investigated, the clearer the picture of climate change would 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,” she said.

Islands sensitive to changes in climate

The southern hemisphere is predominantly ocean which, she said, makes it difficult to pin down land-atmosphere interactions.

Rudolph said the interaction between ocean, atmosphere and land remained complex, saying this is why it was important to study the entire picture to fully understand how this was happening, especially since the climate was changing at a drastic rate.

Rudolph said the sub-Antarctic islands were sensitive to changes in climate.

“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 land forms will still be evident in the landscape years later under a different climate, for example, warmer or drier conditions. We can study these land forms in real time and establish whether they are actively forming or are relict features that formed under different climatic environments,” Rudolph said.

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