“The mosses are our sentinel for the whole ecosystem.” Vegetation in Antarctica is changing rapidly in response to a drying climate report scientists studying ancient moss beds near Australia’s Casey Research Station in East Antarctica.
Antarctic mosses are the only plants that can survive in the harsh environment. “We like to think of them as miniature, old growth forests,” said lead scientist Sharon Robinson from the University of Wollongong, in Australia.
“Visiting Antarctica, you expect to see icy, white landscapes,” said Robinson. “But in some areas there are lush, green moss beds that emerge from under the snow for a growing period of maybe six weeks.”
Emerging from the ice for a brief growing season every Antarctic summer, reports Victoria Gill for BBC News, the lush green mosses of East Antarctica are finally succumbing to climate change, according to a study of the small, ancient and hardy plants – carried out over more than a decade.
While West Antarctica and the Antarctic Peninsula are some of the fastest warming places of the planet, East Antarctica has not yet experienced much climate warming, so the scientists did not expect to see much change in the vegetation there.
“But we were really surprised when we saw how fast it was changing,” Prof Robinson said. “After a pilot study in 2000, we set up monitoring in 2003. When we returned in 2008, all these green moss beds had turned dark red, indicating they were severely stressed. It was a dramatic change. They change from green to red to grey if they get really stressed. The red pigments are the sunscreen and drought stress protective pigments they produce to protect themselves – antioxidant and UV screening compounds. Grey means they are dying.”
When their study started, the moss beds were dominated by a species called Schistidium antarctici, which can survive long periods under water. By 2013, many of the beds the team studied were being encroached by two other moss species that thrive in drier conditions and are less tolerant to being submerged. East Antarctica, the researchers say, has become colder, windier and drier due to the combined effects of climate change and ozone depletion.
“The ozone hole has pulled the polar jet stream further south, increasing its strength,” explained Prof Robinson. “These winds isolate Antarctica and help to keep most of it cold as the rest of the world warms.”
Her co-author, Dr Melinda Waterman explained that by dating the mosses, the researchers could tell “they have been growing here for hundreds of years. As they grow, the mosses preserve a record of how dry or wet the environment is along their shoots – preserving a record of Antarctic coastal climate over the centuries,” she explained.
Prof Robinson added: “[They might be only] 4-14 cm tall, but [the moss beds] are home to tiny animals and fungi and lichens and algal cells – think of them as a forest and at least 40% of it is suffering drought.
The broader message from the study, Professor Robinson said, is that nowhere on Earth is spared the consequences of climate change.
“We think of Antarctica as a pristine wilderness but climate change and ozone depletion have a huge impact there. What we do in the rest of the globe affects the plants and animals in Antarctica,” she said.
At the same time, what happens in Antarctica affects the rest of the globe; as the westerlies that circulate Antarctica move poleward, they are changing weather patterns across the Southern Hemisphere.
“Another message from this is that we don’t necessarily anticipate the consequences of what we do. We knew ozone depletion would increase UV radiation, but it was decades before we knew it affected the climate,” Professor Robinson said.
“Those shifting winds are affecting southern Africa and South America and Australia because they are pulling all the weather bands to the south. Some areas are getting wetter, and big areas that were wetter have got much drier. It’s affecting how trees grow in New Zealand. It’s affecting the southern tip of Chile where trees are growing less well, forests are contracting and there’s less water for hydroelectric power plants.”
Supported by UOW’s Global Challenges Program, the researchers will continue to monitor the impacts of climate change on Antarctica.
Image credit top of page with thanks to photographer Mark Thomas, Getty Images. Chinstrap penguins on a melting glacier. View the Mark Thomas portfolio here.
The Daily Galaxy via University of Wollongong and BBC Science
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