Study finds first evidence of climate change impacts on East Antarctic vegetation

A 13-year historical study published in Nature Climate Change provided the first evidence that climate change is affecting the terrestrial ecosystems of East Antarctica.

Western Antarctica and the Antarctic Peninsula are among the hottest places on the planet, but East Antarctica has not warmed up in the same way and seems to have grown up. Here escaped the most important impacts of climate change.

The study, conducted by researchers from the University of Wollongong (UOW), the Australian Antarctic Division and the Australian Nuclear Science and Technology Organization, showed that Antarctic vegetation

Eastern Antarctica, say the researchers, has become colder, windier and drier due to the combined effects of climate change and depletion of the ozone layer.

Beginning in 2000, researchers monitored ancient moss layers near the Casey Australian station. The lush green moss bed of Casey, known as the "Daintree of the Antarctic", is the largest plant ecosystem in East Antarctica.

Principal investigator Sharon Robinson, of the Center for Sustainable Ecosystem Solutions of the UOW School of Biological Sciences, said that when researchers began monitoring the foam bed in 2000, they thought that any change found would be very gradual.

"We were very surprised to see how quickly the situation was changing, and after a pilot study in 2000, we started monitoring in 2003. When we returned in 2008, all these green moss beds turned red. has been a dramatic change, "she said.

In search of the cause of the stress, the researchers found evidence of a drying climate. One piece of evidence was the change in species composition.

When the study began, the foam beds were dominated by Schistidium antarctici, a species that can survive long periods under water, that Casey's moss layers have often been during the brief summer of Antarctica. In 2013, two other moss species invading many of these areas develop in drier conditions and are less tolerant of submersion.

Dr. Melinda Waterman, research associate at UOW and co-author, also found evidence of drying in the foam shoots themselves, which, like tree rings, retain a trace of past climate.

"When we locate the nuclei of the moss shoots, we get these signatures that tell us how wet or dry they were during their growth.Some of the mosses are hundreds of years old, which gives us a very good record. for this part of the Antarctic, "said Dr. Waterman.

"We used the pulse of the radiocarbon bomb – the peak of radioactivity in the atmosphere caused by the nuclear weapons tests that culminated around 1965 – to accurately date the foam cores and found that many foams grow in drier conditions than in the 1960s.

"Of the 18 foams we sampled, most showed signs of drying out and 40% showed signs of severe desiccation-only three showed no drying out."

Data from the stations of the Bureau of Meteorology in East Antarctica show that they have become colder and windier during the same period.

"The fact that the summer is colder means there is less melt water – it never rains there, so all the water has to come from the melting snow and ice, "said Professor Robinson.

"All these elements tell us that it is drier and is related to this change in wind." The hole in the ozone layer and climate change have brought west winds closer to the Antarctic. increased wind speed and drier

"This is the first evidence that eastern Antarctic communities have been affected by climate change and the depletion of the ozone layer.

Professor Robinson said the broader message of the study is that the consequences of climate change are not spared.

"We think Antarctica is a pristine wilderness, but climate change and depletion of the ozone layer have a huge impact there.What we do in the rest of the world affects plants and animals in Antarctica ".

At the same time, what happens in Antarctica affects the rest of the world. As the westerly winds circulate in the Antarctic, they alter the weather patterns in the southern hemisphere.

"Another message is that we do not necessarily anticipate the consequences of what we are doing.We knew that the depletion of the ozone layer would increase UV radiation, but there have been decades before it affects the climate, "said Professor Robinson.

"These changing winds affect southern Africa and South America and Australia because they draw all the weather bands south. Some areas become wetter and the larger, wetter areas are much drier. This affects the southern tip of Chile where trees are growing less well, forests are contracting and there is less water for hydropower plants. "

Supported by the UOW Global Challenges program, researchers will continue to monitor the impacts of climate change on the Antarctic.

"Our monitoring methods in East Antarctic allow us to track the response of moss communities to a changing climate, and are integral to monitoring terrestrial and terrestrial communities with minimal impact in the Antarctic continent. and Earth Observation System (ANTOS), an international collaborative program that we are contributing to with our new interdisciplinary ECO-Antarctic project on global challenges, said Dr. Waterman.

Explore more:
Climate change delays growth of centuries-old Antarctic moss shoots

More information:
Sharon A. Robinson et al. Rapid change of terrestrial vegetation in East Antarctica in response to regional drying, Nature Climate Change (2018). DOI: 10.1038 / s41558-018-0280-0