Antarctic moss. Image: Sharon Robinson/University of Wollongong
The vegetation in Antarctica is succumbing to damage caused by climate change, according to researchers from the University of Wollongong in Australia.
A 13-year study published in the journal Nature Climate Change has provided the first evidence that climate change is adversely affecting terrestrial ecosystems in East Antarctica.
West Antarctica and the Antarctic Peninsula are among the locations in the world that are warming the fastest. Up until this study, it was not thought that East Antarctica experienced these changes in the same way.
Climate change is drying out ancient moss
The study from researchers at the University of Wollongong (UOW), the Australian Antarctic Division and the Australian Nuclear Science and Technology Organisation found that vegetation in East Antarctica is transforming in response to a drying climate.
In 2000, the researchers began by monitoring old-growth moss beds near Casey Station, a research outpost in East Antarctica. The moss beds found in some areas generally grow for around six weeks. According to lead researcher Prof Sharon Robinson, the team thought when they first started that any changes they saw would be gradual, so the rapid transformations surprised them.
Researchers were quick to set up monitoring in 2003, following a pilot study. “When we returned in 2008, all these green moss beds had turned dark red, indicating they were severely stressed. It was a dramatic change,” Robinson said. The red colour indicates the presence of sunscreen and drought stress protective pigments the plants produce to protect themselves.
Researchers uncovered evidence of a drying climate when they began the search for the cause of this stress. They found that the changing species composition may be playing a role.
When the study commenced, Schistidium antarctici, a species that can survive for long periods underwater, dominated the beds. The Casey moss beds were often submerged during Antarctica’s brief summers. By 2013, two other moss species that thrive in drier conditions and are less tolerant to being submerged infiltrated these areas.
Examining the climate history of Antarctica
Co-author of the research, Dr Melinda Waterman, said the team also found evidence of drying in the moss shoots themselves. The shoots preserve a record of past climate, much like tree rings.
Waterman said: “When we trace down the moss shoot cores, we get these signatures that tell us how wet or dry it was while they were growing. Some of the mosses are hundreds of years old so they give us a really good climate record for this part of Antarctica.
“We used the radiocarbon bomb pulse – the spike in radioactivity in the atmosphere caused by nuclear weapons testing which peaked around 1965 – to accurately date the moss cores, and found that many of the mosses are growing in drier conditions now than in the 1960s.
“Of the 18 mosses we sampled, most showed evidence of drying and 40pc showed evidence of significant drying. Only three didn’t show drying.”
Information from the East Antarctica Bureau of Meteorology showed that it had become colder and windier over the same time period. Robinson says the cooler temperatures in summer means there is less meltwater. As it never rains in the area, plants such as mosses need this water to survive.
A global issue
According to the researchers, the ozone hole and climate change have drawn the westerly winds closer to Antarctica. This has increased wind speed and made the climate drier and less temperate.
Robinson added: “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 added that the change in winds is affecting global weather patterns, not just Antarctica. According to Robinson, some areas are becoming wetter while others are drying out. The winds are affecting forestation in countries such as New Zealand and Chile. The researchers are continuing to monitor the impact of climate change on Antarctica.
