Bringing back to life moss in Antarctica
Studying past climate change in Antarctica is important as the continent is a key component of the Earth’s system in terms of influencing and responding to global ocean at atmospheric changes. The ice sheet you’ll see on an Antarctic trip plays a key role in sea level change: if the ice was to melt suddenly global sea levels will rise by around 70 metres. Therefore, monitoring changes in climate as well as the biosphere of Antarctic is critical in understanding and predicting future global climate change.
Linking temperatures with moss growth
Over the past 50 years scientific data has shown the climate of Antarctica to be relatively stable however, this is not so for the Antarctic Peninsula. This particular part of Antarctica has experienced some of the highest levels of warming anywhere on Earth with average temperature increases of 3°C since the 1950s. The result of this rapid increase in temperature has been decreased sea ice extent, ice-shelf collapse, glacial retreat and increase ice flow rates. There has even been changes in the ecosystems on land and in the sea. However, scientists have been unable to precisely determine the reason for this rapid warming: the ozone hole and rising carbon emissions play an important role but don’t fully explain the rise in temperatures. To gain a better understanding on the impacts of climate change on Antarctica scientists are using an interesting and unique tool to reconstruct past temperatures so inferences can be made on future global and Antarctic system changes: The tool is moss banks. In the Antarctic Peninsula there is a vast variety of moss species, in fact there is over 100 species, in addition to over 25 species of liverworts and 300-400 species of lichens and over 20 species of macro-fungi. The greatest diversity is found along the western side of the Antarctic Peninsula where the climate is typically warmer and has more precipitation than elsewhere in the Antarctic continent.
Climate data from moss banks
Scientists have found that moss banks are idea deposits to reconstruct past climate change on the land surface area of Antarctica as moss banks have accumulated over the past 5,000-6,000 years at locations on the continent particularly the western Antarctic Peninsula. Moss banks are an interesting feature in Antarctic as they can be up to three metres deep and are permanently frozen below the active layer. With many moss banks found it means that comparisons of growth rates between locations can easily be made as they are easily measurable as core samples can be extracted for analysis back in the lab and they preserve well. Scientists therefore can use a range of proxy indicators of past climate (stable isotopes, measures of decay, moss morphology etc. to reconstruct climate variability.
A British Antarctic Survey (BAS) study found that increases in temperature on the Antarctic Peninsula during the latter part of the 20th century matched an acceleration in moss growth. A team of scientists from BAS, University of Cambridge and the University of Exeter took samples from the most southerly known moss bank at Lazarev Bay on Alexander Island. The scientists extracted a peak core from the bank and used radiocarbon dating to determine the start of peat accumulation. The testing is so precise that was determined to have formed in 1860.
Matching moss growth with local temperature recordings
Scientists from BAS have recorded temperature rises in the Antarctic Peninsula of 1-1.4°C over the 1980s and 1990s. In addition precipitation levels have increased while the length of the melt season has increased since 1948 with early thawing and later freezing. The changes have reduced ice cover exposing land for a variety of flora to colonise, the most common form being moss. The moss samples taken from the BAS and university team showed that it had grown around 1.25 mm a year throughout the late 19th and early 20th century before growth suddenly increased in the mid-1950s to reach 5 mm a year by the late 1970s. However, its current growth rate has slowed down to reach around 3.5 mm a year. The importance of this finding is that the researchers had clearly demonstrated a substantial increase in plant growth since the 1960s coincides with changes in the local climate.
A link between warm temperatures and soil fungi
Meanwhile BAS scientists have found a direct relationship between warmer temperatures and diversity of soil fungi on the Antarctic Peninsula, which plays an important role in supporting the fragile ecosystem in which they are found in. The study investigated potential changes in soil fungi with scientists determining that if temperatures on the Antarctic Peninsula continued to increase by a similar around as they did between the 1940s and beginning of the 21st century soil fungi diversity in Antarctic soils could increase by up to 27% by 2100. This in turn will make the soil more nutrient-rich, hence more productive for other species to thrive in. The study also used DNA sequencing to measure the number of species present in 29 soil samples gathered along 1,650 km of the Antarctic Peninsula during the 2007/2008 summer season. Many of these sites were previously unchartered and so the scientists had to gain access to some by helicopter or from small boards from HMS Endurance. The results will provide a wealth of data for research to come as it’s the largest survey of soil organisms every undertaken on the Antarctic Peninsula to determine how these ecosystems will change with rising temperatures.
Bringing back to life moss in Antarctica
Another interesting study conducted by BAS and Reading University scientists was the bringing back to life of moss that had been frozen in ice for 1,500 years, demonstrating that it can come back to life and continue to grow. For the first time this study shows that moss has the ability to survive ice ages that not only last for a century but ones that last for thousands of years. This is the first study that has found long-term survival of any plant. The only other similar timescale has been seen in bacteria. Previous studies of moss had only examined short term survival lengths with studies finding they could bounce back after 20 years. To regenerate the moss the scientists slice the frozen moss core open keeping them free from contamination and then placed them in an incubator at normal growth temperature and lighting conditions. After only a few weeks the moss began to grow. The team then used carbon dating to identify its age and found it to be at least 1,530 years old. The scientists even speculate that moss could be grown globally at ease to act as carbon sinks, sucking up carbon emissions from the atmosphere. In addition, this research provides evidence that even more complex life forms could potentially survive long periods of time once encapsulated in ice or permafrost.
Not every aspect of climate change favours moss growth
However, not every aspect of climate change is a friend of every moss specie with research from the Australian Antarctic Division revealing that one species of moss, Schistidium antarctici, with its growth particularly affected by ozone depletion, while increased temperatures positively affect its growth rate. The moss is affected by UV-B radiation as it has a low concentration of sunscreen compounds. Meanwhile the scientists found that increased wind speeds was detrimental to the mosses growth as the wind dries out the wet conditions mosses prefer.