Among ancient moss forests

Observing twenty-five years of change

IT WAS FEBRUARY 2022 when I started writing this essay, and I was returning from three weeks in Antarctica. As we flew back to Hobart I caught glimpses through the clouds of massive, glistening white, tabular icebergs suspended in semi-­transparent sea ice in the intensely blue Southern Ocean below. From the sky the bergs look tiny, but are kilometres long. We had just completed intense work monitoring the moss beds in and around Casey Station. Two flights were due to leave Wilkins Aerodrome that day – ours and a second flight, an Australian Airforce C-­17, that would bring the rest of the team and our precious cargo of samples back to Tasmania, the first step in their journey to the Janet Cosh Herbarium at the University of Wollongong. This is where the moss would be identified and added to the only set of data monitoring long-­term continental Antarctic vegetation – data that have revealed how humanity’s changes to our climate are damaging even these remote ecosystems.

This trip marked twenty-­five years since I first went to Casey. The first time was on the icebreaker Aurora Australis – eight days churning through the Southern Ocean to reach the edge of the sea ice and my first, magical helicopter ride over and around those fabulous icebergs. By air, the trip takes four hours, with the first sight of the continent often occurring as the plane emerges from the cloud and is about to land. This is a very different introduction and departure. In 1996, I had been part of the fiftieth Australian National Antarctic Research Expedition (ANARE), arriving on the first ship of that season at the end of October and departing at the end of the following January. This year I was part of the seventy-­fifth ANARE for three weeks in February. In 1996 I was a newbie to this field, seeing Antarctica through fresh eyes. This time I was leading a team of six early-­career researchers as part of the new Australian Research Council Special Research Initiative: Securing Antarctica’s Environmental Future.

Despite frequent visits to both East Antarctica and to the peninsula, each trip is exciting, and this year was particularly special, seeing the continent through the eyes of these next new researchers, some of whom were making their own first trip. This next generation of scientists is powerful when advocating for its research, passionate about why it is important and determined to make a difference. Their enthusiasm makes me confident about the future of Australia’s Antarctic science and gives me hope for the future of Antarctica and the planet.


CASEY STATION, ONE of Australia’s three stations on the continent, is almost 4,000 kilometres away from Hobart, roughly level with the longitude of Perth. It is home to some of the most extensive moss beds on the Antarctic continent and has two Antarctic Specially Protected Areas. These are areas that have been closed off and can only be visited with a permit – in this case to protect their rich flora.

Green is unexpected in Antarctica, and the sheer exuberance of the Casey moss beds always takes my breath away. Nestled in among the grey, black, yellow and pink rocks and the endless white ice are oases of green moss turfs; they surround calming blue lakes or skirt babbling brooks. The moss is contorted into ridges and valleys by the constant freeze-­thaw of the conditions it experiences. On a micro scale it resembles alpine landscapes with green, moss-­covered valleys, rising to hill tops covered in colourful, and sometimes hairy, lichens and topped by dramatic quartz micro-­tors that stand just a few centimetres high. When the low evening sunlight streams over the larger of the moss beds, they appear intensely vibrant. Some mosses look like tiny spikey asparagus shoots while others have the sensuous appearance, and touch, of velvet.

I first went to Casey as a new lecturer from the University of Wollongong. My introduction to Antarctic science had been serendipitous; I was working on pigments that plants produce to protect their leaves from too much light. Talking at a conference about the role of leaf pigments in young rainforest leaves, which are often pink or red – like the pink flush of Syzygiums (lilly pillys) – the biologist Adele Post came up to me. ‘If you are interested in red pigments, you should study Antarctic mosses,’ she said. ‘They go red in summer.’

I was instantly intrigued. Could this be an example where increased ultraviolet light from the ozone hole was causing Antarctic mosses to make their own sunscreens? By training, I’m a biochemist and physiologist, and I am interested in how plants work. Antarctic mosses are fascinating in this respect because they can survive in extreme conditions.

And so I did what scientists do: I designed an experiment to test my hypothesis and applied for an Australian Antarctic science grant to fund the work in 1995. It was my first successful application. From 1996, it gave me two berths to Casey for the next three summers, starting with that first three-­month trip. I went with a young volunteer, Jane Wasley, who later became my first PhD student and so began her own career in Antarctic science. Starting that first summer, Jane brought an ecological perspective to our research. Her interest in how water and nutrients were driving moss distributions was further developed through her PhD to become the second major theme in our research.

Like other plants, Casey’s lush green moss beds need water, nutrients and light for photosynthesis. They are extremely hardy and I like to think of them as true Antarcticans. The plants and the minute animals that live in these mossy forests are all freeze-­tolerant and they thrive despite having fewer than three months a year in which to grow. While most of the charismatic megafauna, like penguins and seals, come for the summer to breed and feed, they leave for winter. Mosses tolerate up to nine months a year dried out and frozen under snow. They then manage to grow during the short summer season when ice melts and freshwater is available. Their dark pigmentation allows them to absorb sunlight and warm up, like basking reptiles. This means moss surface temperatures are frequently above 20 degrees Celsius, despite the air temperature rarely getting above 2 degrees. This pigmentation also helps them melt the snow above them – essentially they warm it from beneath – and this provides them in turn with valuable water. In locations where conditions are especially tough, Antarctic mosses can survive under quartz rocks. They grow in these mini glasshouses protected from the harsh winds and extreme temperatures.

Our work has shown that Casey’s moss beds thrive in areas where ancient penguin colonies were once situated. Between 3,000 to 8,000 years ago, these moss beds were nesting sites for Adélie penguins. The evidence for this comes from tell-­tale signs: hills covered in graded stones, all the size that could be transported in an Adélie penguin’s beak; fragments of eggshells; the bones of long-­dead penguins and penguin poo – like an ancient assemblage of blood and bone meal. This freeze-­dried ancient guano left behind by birds years ago promotes current plant growth, which provides us with clear evidence that things do not degrade in Antarctica’s cold conditions. When you know what to look for, you can see these Zen gardens across the Windmill Islands – the region where Casey Station is situated – and this past prime real estate for penguins now supports lush moss beds decorated with rocks and lichens. Occasionally, when we are working in the moss beds, an Adélie penguin will wander over. To everyone’s delight, the penguins are unaware of the distance rules for approaching wildlife imposed on human visitors and will come within metres of us to check what we are up to. I think of these visits as confirmation of place and belonging, as if the penguins are responding to the stories the landscape tells still.

To live briefly on an Antarctic station is to be part of a small community predominantly made up of tradespeople, all highly skilled in their own areas and all usually very interested in the environment. We always get a lot of interest in our projects, and the rise of digital cameras and macro lenses has sparked increasing engagement with everyone from chefs to Bureau of Meteorology (BOM) techs regaling us with their own wonderful images of mossy landscapes. My team has always tried to foster station community interest by showing how special the Casey moss beds are. We’ve made posters for the mess hall, given talks and held science open days. This year’s open day combined high-­tech drones and spectral sensors with a tour through tiny moss forests, revealing tiny creatures – tardigrades or ‘water bears’ – and moss leaves, both favourites with our audience. Observing tardigrades ambling around or dried moss leaves unfurling in a drop of water through the microscope lenses helps to illustrate the life that is out there if we only look down.


ONE OF THE most frequent questions we are asked on station is how the mosses are responding to climate change. When we began our moss journey in the late 1990s there was no long-­term monitoring of the mosses underway, which meant we couldn’t really give an answer.

But Jane’s PhD research highlighted that this lack of long-­term data represented a fundamental gap in knowledge about Antarctic terrestrial ecosystems, not just at Casey but all over the continent. So we were delighted when the Australian Antarctic Division (AAD) asked if we could develop a State of the Environment (SOE) indicator for the mosses. This would be the single, biological indicator in a sea of physical parameters that were already being collected for Antarctica, such as data points for temperature and windspeed trends.

Physical factors are easier to count in real time, and these measurement processes are easy to automate: we already have thermometers and aeronometers positioned at meteorological stations around the world collecting the climate data that inform our daily weather forecasts.

Think of it this way: during our own regular health checks, a doctor uses a manometer to measure blood pressure; they count our pulse rate. These physical data provide easily assessable information about the underlying health of our organs and, until the advent of medical-­imaging techniques, were often the best information we could glean. Assessing moss health needs the same kind of hands-­on sampling and observation, and so we designed a system that could be achieved in less than a week of good weather. This short sampling snapshot would allow the survey to be done within the time that the annual station resupply ship is docked. Jane Wasley and another student, Johanna Turnbull, set up a pilot site in 2000 and installed two SOE monitoring sites in 2003. One is in a Specially Protected Area next to Casey Station in a site that is recovering after disturbance by station operations in the 1970s and 1980s; the other is a more pristine site to the south at Robinson Ridge. We have been resurveying these sites every few years, whenever access and logistic support has been available.

Given how slow mosses grow, I didn’t really expect to see much change before I retired, but we still thought it was an important thing to establish a baseline of knowledge for the future.


AS WORK BY Lesley Hughes and others has shown, long-­term monitoring contributes significantly to the development of good policy and management options and provides impactful science outcomes across a range of landscapes. Through our own work, we know now that the Casey moss beds are drying out as a result of climate change – the process driven by ozone depletion and global heating. We know this because we saw the appearance of those mosses change rapidly – much more quickly than expected.

In 2003 we started off with lush green moss beds. By 2008, extreme climatic events had turned them almost uniformly red – thanks to the production of the pigmentation that had originally lured me to Casey. Over the next five years, some moss recovered to verdant green health but other patches have continued to show declining health, changing from red to brown to grey. Some are now starting to be overgrown with lichens. So despite predictions – made by our team and by the Intergovernmental Panel on Climate Change (IPCC) – that terrestrial community change in Antarctica would be slow and difficult to detect, we now know these are dynamic communities that respond to extreme events in the same ways that other ecosystems do.

These results spurred us to investigate the age of the mosses, which led us to discover that the Windmill Island communities are old-­growth moss forests. These same plants have been growing for hundreds of years, since before what’s known as the ‘heroic’ age of human exploration and exploitation in Antarctica, from the late nineteenth century to the end of World War I. We know too that they preserve a signature of past climate in their tiny stems like tree rings, speaking their own history of place to us. And we know that moss species are on the move in Antarctica, with species that prefer dry conditions moving down into drying areas that were previously too wet for them. These Antarctic moss communities were one of nineteen communities in Australian territories identified as being at risk of ecosystem collapse in a landmark study published in 2021, which also suggested strategies to manage them into the future.

Our body of work, published in prominent scientific journals, has rewritten our knowledge of East Antarctic ecosystems and has informed recent IPCC and United Nations Environment Programme reports. And, as originally intended, it also continues to inform Australia’s SOE reports every six years, while being reported to other parliaments across the world as part of their treaty obligations. It has proved to be an area where Australian science leads the world.

Yet despite this, monitoring goes through periods when it isn’t fashionable – when it’s dismissed as a scientific equivalent of stamp-­collecting – and this contributes to a critical disconnect between the requirement that grant schemes fund what’s perceived as cutting-­edge science and the need for monitoring to be consistent over time in order for it to have value. The usual lifetime for a grant is between three and five years, which is an insufficient window to support long-­term monitoring. And other mechanisms for funding have to date been unavailable for this type of study. Despite being asked by the AAD to develop the Windmill Islands monitoring scheme, its funding still had to be obtained through the Australian Antarctic science grant scheme, and this only supported the first three years – effectively one year of set-­up and the collection of initial measurements. Every five years, we have had to reapply for funding to undertake the next set of observations and measurements. Sometimes we proved to be successful, other times not. And each project we submitted would be peer-­reviewed and assessed against changing criteria that usually did not emphasise the importance of baseline monitoring. Weeks were spent writing grants – and then rewriting them if we were unsuccessful – with new ‘innovations’ introduced every time so that a project could be seen to be novel and cutting edge, even while it maintained the core monitoring components required for the consistency of the long-­term records.

When we were asked to start the SOE project in the early 2000s, SOE monitoring was in fashion. Twenty years later, in 2021, the O’Kane Review into Australia’s Antarctic science recommended the development of an East Antarctic Monitoring Program as a key component of Australia’s approach, and so monitoring once again became important. But we have faced real difficulties getting berths on the station and funding to support collection and analysis of these data in the intervening twenty-­two years.

To some extent, this is the life of the scientist, and maybe the advances we have made in our research more broadly would not have happened without that constant pressure to innovate and rethink our grants. But the danger is that long-­term observations such as these are lost because researchers give up the hunt for support. Sometimes we certainly felt like walking away, but buoyed by the support of peers and colleagues who recognised the importance of the work we persisted, confident that what we were doing had value. As a consequence, we now have data from 2003, 2008, 2013 but not 2018: our latest data set was collected in 2022 – exacerbated by Covid delays from 2020. This represents only a fraction of the lifetime of these old-­growth moss beds.

And while monitoring biodiversity is important, it is also important that we are collecting these data for a purpose. That work we are doing in the field in Antarctica and back in the lab in Wollongong should be informing action; if it does not, then it is a waste of time and considerable resources. As scientists we do not want to document the decline of another ecosystem only for that information to be published but ignored. I want this knowledge to be used to prevent further damage, to underpin action to prevent further climate damage and, more locally, to inform better management of Antarctic ecosystems. One missing part of this equation – and one we want to address within the new program – is what we do with this data as custodians of these precious ecosystems.

We need to ensure that this is information of value.


THE THING THAT I love about Antarctic research is the internationality and the interdisciplinarity it allows. The international treaty system dates from 1959 and has been strengthened over the years to now include fifty-­three nations. It stipulates protection of the Antarctic wilderness, freedom for science and an open sharing of scientific data and outputs. Antarctica is unique in that no country has jurisdiction over its space and all military operations are banned. This gives Antarctica’s international community a real strength and has allowed me and my research team to visit stations supported by other national programs, including Chile’s and New Zealand’s. It’s provided invitations to work with other research groups across the world and, in return, we have hosted students and other researchers in Wollongong. The Scientific Committee on Antarctic Research runs an Open Science conference every two years – and I love that I can go to sessions on glaciology, climate and marine science as well as biology.

But it’s on station, and usually over food, where many useful discussions occur that frame the science we do and the way we do it. You might be sitting next to a glaciologist or an atmospheric scientist and serendipitous connections, ideas and collaborations can blossom as a result. Equally, you might be sitting next to a polar tradie who’s been battling the Antarctic elements for months and is the expert you need to solve an engineering problem. On our first project, which investigated the impact of the ozone hole on mosses, Casey’s carpenter helped ensure that our experimental light filters would stay in place for two summer seasons and survive wind gusts that can get up to 200 kilometres per hour. One of the BOM technicians took photos for us throughout the year so we could see how the snow piled up on our sample sites over winter and melted out over spring.

These connections have allowed me to embrace new interdisciplinary techniques to answer questions about Antarctic terrestrial communities. We have developed new techniques, including the use of radiocarbon in the atmosphere, to date Antarctic mosses. When atmospheric nuclear testing created a bomb pulse in radioactivity in the mid-­1960s, I was being taken on Ban the Bomb marches in London by my parents and the Casey ‘Tunnel’ – the first Australian station on this site, and the precursor to the current base – was being built. The nearby mosses took up that extra radioactivity, effectively time stamping 1965 in each moss shoot. Using this marker, we can tell how old the mosses are and how slowly they grow (between one and three millimetres a year). Using stable nitrogen isotopes, we can tell where the mosses get their nutrients – whether it’s from gaseous ammonia that wafts on the wind from nearby penguin colonies or from ancient freeze-­dried guano deposited thousands of years ago. These isotopic signatures are also preserved in older herbaria specimens, so in future we can analyse samples collected by British botanist Joseph Hooker or Douglas Mawson as they explored the South Hemisphere in the mid-­nineteenth and early twentieth centuries, respectively. Using other stable isotopes of carbon, we can tell how wet or dry conditions were when a specific part of the plant was photosynthesising and growing. In this way, mosses are like mini coastal ice cores, slowly accumulating carbon and recording the Antarctic environment as they grow.

Once we realised that our long-­term monitoring was revealing rapid changes in moss health, we needed a way to scale our techniques to encompass the whole moss bed. Working with the TerraLuma group from the University of Tasmania we have used drones to map the moss beds at fine scale (down to square centimetres) and special sensors to investigate moss-­health changes over time. Some of these techniques can also be applied using satellite data – although at closer to a square metre, the pixel size is often too large for it to be useful. But mapping with drones is ideal: it reduces the need to enter moss beds, thereby reducing the chance of damage to these ancient communities. When we optimise these sensors and their image analysis the chance to check these communities frequently and non-­invasively will open up. Perhaps in the future our sampling could potentially be performed by drones – with data from our original low-­tech monitoring program still providing valuable ground truth to validate data collected by any future sensor technologies. But for now we still need to collect those tiny moss shoots to ensure the ongoing integrity and longevity of this important SOE indicator.


AUSTRALIA’S CLAIM TO 42 per cent of the Antarctic continent comes with a responsibility to protect the region. And our work helps to highlight how the impacts we cause in the rest of the world – from nuclear testing to ozone depletion to climate change – affect the whole planet, including these tiny plants that grow so remotely. Increasingly, our work is aimed at providing environmental managers with the tools and solutions to protect this diversity. Given Antarctica’s crucial role in the Earth system, it also emphasises the need to take action on climate change.

The Montreal Protocol is rightly lauded as an example of a successful environmental treaty where all countries acted to phase out ozone-­depleting compounds. But despite this, the ozone hole still appears over Antarctica each spring forty years later – and it will be 2060 before it recovers to levels observed in the 1970s. As recent IPCC reports have stressed, we need to eliminate greenhouse gases fast to allow the planet’s atmosphere to recover and to avoid the catastrophic effects in Antarctica that would have repercussions for the rest of the world. Hopefully our long-­term monitoring project has both helped to show that Antarctic biodiversity needs our help – and reinforced this vital message about change.

Back in Australia after our 2022 summer expedition, and finishing this essay in March, it’s impossible to ignore how fast the world can change. When I was an undergraduate, we were worried about the possibility of nuclear winter. This March Russia invaded Ukraine and the spectre of nuclear weapons – whose predecessors marked Antarctic moss stems and which I’d long consigned to the space of childhood fears – has resurfaced. Fears of that nuclear winter, too, have given way to a world where we’re only too aware that the planet is overheating, resulting in weather events from heatwaves and bushfires to intense storms and flooding rains. Over my academic lifetime, climate change has gone from being a topic of interest limited to a few climate scientists to become an existential threat that affects us all. This March Antarctica experienced an unprecedented heatwave with temperatures up to 40 degrees Celsius higher than normal and, while students strike for climate – again – around the world, the Conger ice shelf, all 1,200 square kilometres of it, collapsed completely in East Antarctica.

Antarctica is a continent of extremes – coldest, driest, windiest, highest. It also spans a huge range of scales from the sheer vastness of the icy plateau, icebergs and sea ice to the marvellous microscopic world of the ancient moss forests that we work on. But its vulnerability to climate change affects its whole. The ice is as vulnerable as the mosses and they both need us to pay attention to their stories.

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