Ecosystems as early warning signs
Late 2022, our book author, Dana Bergstrom, published in the Griffith Review 's special volume on all things Antarctic: Real Cool World (#77). Here is her the essay for your reading delight. (15 - 20 min read)
I KNOW THESE things. A recognisable and deep clunk as I walk along the cobble beach, its round rocks moving like bowling balls, crashing underfoot. A learned response of ankle flexion to maintain balance. An automatic eye that seeks out the flatter, more stable rocks that allow faster passage. The sound of a satisfying rumble as waves retreat from the shore, and the unmistakable and heady smell of rotting kelp mixed with dimethyl sulphide: the smell of the sea. Am I walking the coastline of subantarctic Macquarie Island? Alas no. This is one of the volcanic cobble beaches on Tasmania’s Derwent Estuary and, lucky for me, near to home. Beautiful in its own right, but special for its transporting abilities – it’s a wonderful aide-mémoire to one of the tiniest jewels on the planet.
I’m approaching sixty. As I skip over the mudstone platforms to get to this special beach most mornings, I don’t feel any different to how I felt as the young twenty-one-year-old who was first given an opportunity to study on Macquarie Island, a thirty-four-kilometre-long sliver in the Southern Ocean, about halfway between Tasmania and the Antarctic continent. But here I am, having spent almost two-thirds of my life so far studying and contemplating life in Antarctica and the subantarctic.
I’ve learnt so much about the physical and living world along the way, but has this life path changed me? The flexible ankle-trick I just pulled off makes me believe it has. I can identify the call of little penguins nearby, feel the heavy flight of a cormorant as it rises, see the flash of a flipper from a frolicking seal in the corner of my eye. And know what these things are. I see echoes of the Antarctic wherever I am: the Derwent River morphs into grey and I know the Southern Ocean has rolled in. A particular light diffused by frosted glass – the right white, a haze of soft – and I’m there again.
Wherever I am, I sense the direction of the wind and I read the clouds.
In these ways, Antarctica, the subantarctic and nature are all-consuming to me.
A FEW YEARS back I had the pleasure of taking one of Australia’s great minds to Macquarie Island – Emeritus Professor Marilyn Ball, environmental biologist, ecophysiologist, Fellow of the Australian Academy of Science. We were walking back to the research station – or should I say, trying to walk – and the weather was foul. A gust hit, lifting us both.
Above: Marilyn Ball in foul weather on Macquarie Island (Image: Dana Bergstrom)
As I watched, Marilyn – who As I had decades of field research experience from other parts of the planet – cartwheeled down the slope uncontrollably. I was aghast at the thought that I may have just broken a living national treasure. But how could I be watching and not tumbling too? When the gust hit, I had instinctively jumped with it, landing softly and safely on mosses instead.
My whole being shaped, maybe even formed, by my journeys down south.
And it’s not just me. The songwriter and composer Dugald McLaren, whose music is permeated with lush imagery and a sense of space, wintered at Casey Station in Antarctica as an electrician in his twenties. We met later on Macquarie Island, and he’s now my partner. His lyrics capture what’s in his heart: ‘Why does a world so cold / Bring fire to my soul.’ Artist Coral Tulloch writes children’s books infused with Antarctic science and sea ice after an initial exposure to its space last century. I think of Dr Barbara Wienecke, penguin biologist extraordinaire; John van den Hoff, seal biologist and naturalist; Dr Patti Virtue, medal-winning krill biologist; my mentor Dr Patricia Selkirk AAM, the pioneering plant biologist: so many of my friends and colleagues have devoted so much of their life in search of knowledge and insight from the south. There’s an almost palpable, perhaps Nordic, vibe to these people – a patience, a persistence, a toughness and, above all, a humility that comes from understanding that nature is bigger and more powerful than they are. Ice in the blood can also generate a fiery passion.
PERHAPS IT was in my genes that I would be attracted to the cold. It’s in my surname, Bergstrom, Swedish for mountain stream. My artist sister, Danelle Bergstrom, also craves nature. But instead of south, she often heads north to the Baltic Sea and the Arctic. The artist’s statement for her next exhibition – Entwined – speaks to my work as well as hers:
"Our relationship with the land and nature is fundamental to our existence.
We need to respect and take care of it, and in turn, it will take care of us."
Above: 'Beckoning' by Danelle Bergstrom, from her Entwined exhibition, 2023
But the real source of our combined love for nature did not arise from anywhere cold, but from Sydney beach combs with our mum, barbecues in urban national parks, the odd holiday camping trip to Kangaroo Valley. My first childhood awareness of Antarctica came from the Australian Antarctic Territory stamps that my aunt had in her collection. Life is full of circles: last year, I had the opportunity of assisting Australia Post with the design of a new Antarctic stamp series featuring lichens. For $2.20 you can grace an envelope with an image of life from one end of the Earth.
Regardless of catalysts, I believe my scientific adventures south have changed me – and for the good. But have I repaid this gift with a particular freight of shared knowledge and insights.
MY FIRST TRIP to Macquarie Island was in 1983, when I was a very young twenty-one.
At that time, Macquarie Island was part of the Tasmanian local government area of the Esperance Municipality (now Huon Valley Council), but a five-day voyage away from Hobart on the MV Nella Dan. But there was that moment, while lacing up my boots on the porch of Bauer Bay field hut, when I looked up in wonder at this wild, west-facing bay, with its hills covered in tussock grasses, its air laced with the bellows of elephant seals. My Dorothy in Oz moment: Toto, I have a feeling we’re not in Kansas anymore. I realised I’d been dropped into somewhere so very much not-Tasmania, not-Australia. I documented the day by drawing royal penguins – but everything was overwhelmingly new to me, the tussocks, the megaherbs, the mosses, seals, penguins, the cold and rain. The mosses, especially.
Above: The wild east coast of Macquarie Island (Image: Dana M Bergstrom)
As an ecology graduate, I had learnt that one of the measures of success in plant life is the extent to which a plant covers the ground. You can record the relative measures of different species’ occupation of a surface as an indication of their significance in an ecosystem. In a forest, the trees and the understorey cover could exceed 100 per cent in total due to some overlapping. But on Macquarie Island, that overlapping was excessive. In expansive meadows, just under the grass canopy, was an equally expansive and thick layer of mosses and liverworts, beautiful in detail and with the most divine, earthy smell. Liverworts do not have any physical protection from being eaten. Instead, their thin-walled cells are full of camphor-like aromatics – I find these addictive, but their chemistry forms bitter-tasting compounds to the tiny snails and other wee beasties tempted to have a nibble.
Bryophytes, mosses and related plants are estimated to have evolved about 500 million years ago, a good two to three hundred million years before flowering plants and dinosaurs. They are still here on the planet and are found from the tropics to the outback. In East Antarctica they are the largest plants present. Keeping low to the ground, simple in structure and function, as well as being able to dry out and then resurrect themselves, has resulted in their evolutionary longevity. They gave me a first lesson in why the KISS principle (Keep It Simple, Stupid) has worked well for biology for millions and millions of years.
Above: balls of moss on Macquarie Island (Image: Kate Kiefer)
MY INITIAL WORK on Macquarie Island relied on the fact that its mosses and grasses did not decompose under eons of consistent, cold, wet conditions. Metres of deep peat have accumulated and they contain records of the past in the form of pollen, spores, seeds and, as I was to find out, other things as well. The focus of my research was Green Gorge, an expansive valley on the east coast of the island, with a sharp line at its back edge that marked the beginning of the slopes. A meandering creek across the valley ended on a shallow crescent-shaped, cobble beach. The beach in summer was a cacophony of activity with elephant seals and king penguins.
Deep in the valley was a strange mound that Patricia Selkirk had cored into. My task was to analyse the fossils that had been unearthed through the many layers of core. I began at the top and worked my way through to the bottom. The 8,500-year story that emerged was one of the waxing and waning of different types of plant cover over the centuries, as grasses gave way to herbs to megaherbs and back to grasses, reflecting the subtle dance of climate and chance.
Above: Green Gorge, Macquarie Island (Image: Dana Bergstrom)
But as I reached the lower levels, I began to see pollen grains I did not recognise. With help from Dr Bob Selkirk, an experienced pollen scientist, we identified the culprit as a little water plant that grew in high-nutrient areas; it more commonly formed mats over elephant-seal wallows. Examining the basal peat samples with a dissecting microscope, we confirmed that we were seeing seeds of this species – and something else. Hairs, lots and lots of animal hairs: the peats were greasy and smelly. Patricia had cored into an ancient elephant-seal wallow, complete with ancient shed skin and seal poo, at a site now kilometres inland and elevated above the current shoreline.
This was my first gathered evidence of major change in an environment, and it was change that spanned thousands of years. The valley had been a bay, the sharp lateral line on the valley wall the old sea level. But the change was not everywhere – fossil signals from a peat slope above the valley at this site showed that vegetation there had changed very little. And revisiting these samples ten years later with new isotopic tools revealed that burrowing birds had used the same slope for nesting for more than 7,000 years. The lessons? Context in space and time was everything. And also, never throw away samples: new technologies will help you find new information in them.
BUT THE PRESENT excited me more than the past, and so after a master’s focused on vegetation history, I progressed to studying the vegetation on Heard Island for my PhD. The privilege of working on one of the most remote and pristine islands on the planet is something for which I am always grateful. The site is 4,000 kilometres from Australia and from Africa and 1,000 kilometres from Antarctica. It’s the wildest of places and, like all subantarctic islands, a haven for wildlife to breed and rest from the perils of the Southern Ocean. The glacial-covered mountain, Big Ben, rises almost 3,000 metres from the sea. Atop of Big Ben is Mawson Peak, an active volcano, complete with a boiling lava lake that we almost crashed into at one point. As the chopper we were riding in fell out of control towards the lake, I was too young for my life to flash before my eyes. ‘What a way to go!’ I thought instead.
Obviously, the pilot regained control.
Above: Heard Island, dominated by the active volcano, Big Ben (Image: Kate Kiefer)
For plant botherers like me, Heard Island is exceptional: mosses so bright and expansive they can be seen by satellite, and the world’s largest cushion plants, Azorella selago. These slow-growing flowering plants, centuries old, can be up to 1.5 metres tall and form vivid green carpets that extend for hectares. They begin as a small rosette of branches shaped like half a dandelion with little bud-like leaves on the tip of each branch. The subantarctic is so windy that the spaces between these branches accumulate sand, dust, spores and debris: in this way, mosses and liverworts colonise the gaps between the leaves. Come winter, the cushion-plant leaves brown off – but they are not deciduous. The leaves stay attached, eventually decaying in this lush, self-constructing compost of stored carbon. Each year, the rosette expands and the cushion gets bigger and bigger; eventually some merge to form carpets. Fungi, tiny nematodes and micro-invertebrates invade the compost, making each cushion a miniature island ecosystem, surrounded by a hostile sea of gravel and snow.
Above: Giant cushion plants, Azorella selago, on Heard Island.
To me, Heard Island is a botanical wonderland as well as a precious World Heritage site.
Cyclones hit the island roughly every three days and the storms are so powerful they move metre-wide boulders along the beach as if they were mere pebbles. Its wild temperament makes me feel small, like a tiny sparkler on the beach that, viewed from Mawson Peak, burns brightly for a millisecond of time.
Even the seals put you in your place on Heard Island. Scrambling back to a field camp one late afternoon, I accidentally woke a large, retired, silver-backed male fur seal. He had seen me all summer; we had even communed for hours as I studied the local plants. However, this afternoon he wanted to remember his lost power – he had no harem anymore. He began to charge from some distance away: I stood my ground and shouted. I mock-charged, waving my arms in the air. He kept coming, snorting rage and fury.
So close now.
I reached forward and tickled his whiskers with my walking stick. Nothing. He kept coming. Deciding on escape, I turned to run and promptly slipped into a putrid elephant-seal wallow. With my face a fraction away from this bath of poo, sloughed skin and ooze, I anticipated the deep bite about to rip into my thigh from his foul-smelling, yellow canines.
Gingerly turning around I saw his smug, satisfied face – yes, almost a laugh. I was low, my head below his, and through this my being showed sufficient deference and respect. He still had it, and these irritating upright bipedal mammals would soon leave his island.
He sauntered back to his spot and settled back for a satisfied snooze. I dripped back to camp, with deference and respect for nature even more firmly tattooed onto my soul.
Above: Fur seal on Heard Island (Image: Kate Kiefer)
I once asked Dr Jon Stephenson, the intrepid geologist who was the only Australian with Sir Vivian Fuchs on the Commonwealth Trans-Antarctic Expedition mid last century, about his time on Heard Island. In 1956, Stephenson had navigated the route for Fuchs’ tractors up to the South Pole and an awaiting Edmund Hillary. In 1963, he summered on Heard Island, a man who had crossed Antarctica by dog sled.
He shook his head at me: ‘Heard? Oh God! What a tough place.’ Australia had named a tidewater glacier on the island after him, a glacier that falls directly into the sea. When I first visited Heard in 1986, this glacier was fronted by a small, intact, swimming-pool-like lake, Stephenson Lagoon, replete with little floating icebergs that had broken off from ice cliffs and fur seal pups playing at the water’s edge. The lagoon itself was evidence that the glacier was retreating. During one storm, we crawled to the edge of the lake to hear the icebergs groan and sing as they were hurled about by the wind. By 2001, my field buddy Kate Kiefer and I had to rope up, work the tides and wear drysuits and life jackets to cross what had become by then the seaward opening of Stephenson Lagoon if we wanted to conduct fieldwork up the coast.
In 2002, aged seventy-two, Jon Stephenson sailed past Heard Island in a tourist ship and noted to Kate that his glacier, ‘like him, was a shadow of its former self’. That tale made me think about how rapid and impactful climate change was, even then; that a glacier, a sentinel in the middle of nowhere, had retreated so significantly in the lifetime of one man.
Above: an aerial view of Heard Island, with Stevenson Lagoon, prominent lower left.
A recent examination of satellite imagery shows that Stephenson Glacier is now almost halfway up Big Ben, and the lagoon has expanded kilometres across the island, breaking out into the ocean in two places. It is beginning to create a strait, which will convert the previously connected land into an island. Here is another indication that the impact of climate change is not playing out across the scale of thousands of years that I saw in my first Macquarie Island vegetation history studies, nor even the scale of the life a man involved in Antarctica’s heroic past. It is dramatically visible in my own working life.
The clarity delivered from studying the more pristine environments, like Heard Island or Antarctica, makes it harder to indulge in that popular fantasy for adults: everything is going to be okay.
MY RESEARCH progressed to looking at the impact of climate change. In 2000, colleagues and I established an international program called Regional Sensitivity to Climate Change (RiSCC). The idea was that warmer, more northerly sites in Antarctica and the subantarctic might be models for change in the future. The scale of that change, we thought, was fifty to 100 years, if not more. The Antarctic region was an ideal place to look for these signals because of that KISS principle – there is less complexity; there is no clearing of ecosystems for agriculture or towns; there is no widespread pollution or mining.
In 2001, we tracked an obscene summer of extreme events extending across the Southern Hemisphere. We linked coral bleaching on the Great Barrier Reef and fires in South America with a heatwave, flooding and rain in Antarctica, as well as the almost instantaneous collapse of the Larsen B Ice Shelf. But we could not get the resulting paper published. In 2001, the scientific world was not ready for such large-scale connectivity. We tried twice more to publish it over the next handful of years – again to no avail. I threw the study in a drawer. The review processes of the scientific journals I chose could not cope with the multidisciplinary science it drew on (climate physics combined with ecology), nor my preferred scientific approach that focused on inductive reasoning and narrative – going from the specified to the general – rather than the classic hypothetic-deductive scientific model. Yet inductive reasoning is all you have in climate studies; you can’t test climate hypotheses because there is no second Earth to experiment on. My climatologist buddy at the Australian Antarctic Division (AAD), Dr Andrew Klekociuk, prodded me to dig it out and update it and eventually we published in 2018. The message of the work was still the same, if not stronger from a longer span of evidence we could include. Extreme climate events can be linked across a hemisphere and often have long-lasting, persistent impacts on the fundamental machinery of ecosystems, relative to their short-term duration.
At Christmas 2008, our prediction of a fifty- to 100-year time scale for observing climate change impacts in the Antarctic and subantarctic came crashing down. Walking back to the station on Macquarie Island, I noticed that many of the endemic cushion plants, Azorella macquariensis, a close relative of the cushion plants on Heard Island, had not woken up from their winter hibernation. On closer examination, many were dead. ‘Endemic’ here means this species is not found anywhere else in the world. Ecologists call these types of plants keystone species or ecosystem engineers because they play such a pivotal role in an ecosystem. Within three years, this species – that had left evidence of its existence and growth in peat cores spanning thousands of years – would be listed as endangered and exhibiting signs of ecosystem collapse. What we had failed to notice was that for seventeen summers in a row, more water had left the alpine island ecosystem than had entered through rain. The plants were stressed and, as is so often the case in humans as well, a disease had then emerged. This loss of cushions has now continued for over a decade, with many of the dead cushions and their centuries of accumulated carbon blown out to sea. My colleague Professor Sharon Robinson from the University of Wollongong had set up long-term observation sites of moss beds near Casey Station in Antarctica as part of RiSCC program – we call these the Daintree of Antarctica. And in the space of a decade, she had concluded that they too were showing dramatic transformation, with Antarctic endemic mosses showing the most loss.
Right: exposed peat, after the death of cushion plant, Macquarie Island.
The rates of change involved here were ecological surprises beyond anything in our experience and imagination. If this was happening so far away from people, what, we wondered, was happening on the Australian mainland? In 2018, with support from the Academy of Sciences, my long-time collaborator Dr Justine Shaw and I ran a Boden Research Conference at the Australian Academy of Science’s Shine Dome to see if such dramatic changes were occurring elsewhere. Eighty scientists turned up – and the stories began to emerge. We ultimately put together evidence for collapse within nineteen exemplar ecosystems from the Australian tropics to the Antarctic coast, west to east and in the mountains. ‘Exemplars’ is the trendy scientific word for a typical example, an ideal or model. But I want to stress that these example ecosystems are the tip of the iceberg and, sadly, there are many more across Australia and the world.
Between the 2018 conference and publication of the study last year, a heatwave again hit Antarctica. Unlike 2001, in January of 2020 the heatwave was not just in one place. It began west of where I was working in the Vestfold Hills at Davis Station. I woke up one morning wondering why it was so quiet and still: it was raining. Opening the blackout curtains on my tiny donga window revealed raindrops on the glass, and watching rain spatter on the windshield of the helicopter later as we flew to a field site felt quite surreal.
Rain in Antarctica. At Mossel Lake, I could not make sense of the sound I was hearing of tiny hammers on glass until I noticed that just under the lake’s ‘wet’ surface was a thin layer of ice. Antarctica is such an alien place.
Daily temperatures reached about 6 degrees Celsius. The weather event moved eastward to Casey where, two days later on 24 January, they had their first recorded heatwave with a peak of 9.2 degrees, almost 7 degrees above the thirty-year mean. It kept travelling around the continent until it reached the Antarctic Peninsula. Here penguins sweltered in the heat of over 18 degrees, their thick feather coat not evolved for such extremes. In Australia, during the same summer, forty-six million acres burned.
Our ecosystem-collapse research had not included the fires. There is a time when you must stop questioning, documenting and researching and simply publish instead. Science knowledge generally increases in increments, and we built on thirty years of conservation science. We followed in the footsteps of earlier work led by Tasmanian climate scientist the late Dr Rebecca Harris using an idea that ecosystems (or for that matter, any system) can experience pressures in the form of chronic presses and short-term pulses. I think of chronic press as like a weight on your back while you are trying to do a push-up, a constant pressure – and these can include phenomena such as increasing air temperatures. Short-term pulses are the extreme events – heatwave, bushfires or land clearing. We divided those pressures into those linked to climate and those resulting from regional human impacts, including feral pests and weeds. Listing seventeen pressures in total, we found that all ecosystems were experiencing or had experienced multiple pressures. Sometimes these occurred at the same time (such as a heatwave and bushfire) or sequentially (like drought followed by floods or, as on Macquarie Island, drought followed by disease). The impact was generally cumulative and degenerative.
The really shocking feature for me was that many of the ecosystems with collapsing elements were some of the largest in Australia: the arid zones, the Great Barrier Reef, the Great Southern Reef. Some were part of or adjacent to our food bowls – such as the Murray-Darling Basin, which produces 42 per cent of Australia’s food.
This was an even bigger realisation. And having seen a keystone species collapse within three years, I speak with the uncomfortable knowledge of how rapidly systems can fall over.
AFTER DECADES OF focusing on Antarctica and the subantarctic, these collapsing ecosystems had brought me back to the Australian continent, which I had not studied since the 1990s. But around halfway along my research journey I had switched out of academia and into the public service at the AAD. And this too influenced my thinking as the landscapes of my work had shaped my self. Because along with questions about how nature works, I asked others: How do we reduce the impact of human activity in Antarctica? How do we make scientific information policy ready? Science uncovers, informs and provides advice: I had morphed into an applied ecologist. And although curiosity-driven blue-sky science is absolutely invaluable to society, I like solving problems.
It’s like wearing permanently tinted glasses: every day at the division is viewed through the lens of the Antarctic Treaty – how nations can collaborate, a focus on the treaty’s Environmental Protocol, and Australia’s pride in being pivotal to its development that emerged parallel to our rejection of mining. For me, the highest level of environmental stewardship is something to strive for, and the protection of values, especially living values – life in Antarctica is central to that thinking.
So as my team of super-bright ecologists assembled to identify and understand the realities of ecosystem collapse, a collective view emerged: we didn’t want to publish another doom-and-gloom work. We wanted to deliver something to the community that would assist change. My adopted focus – and language – of the Antarctic Treaty emerged and contributed to the development of a simple but powerful conservation concept. Known as ‘the 3As’, it’s a place at which to begin. The first is awareness of the value: what is important here? The second, anticipate the pressures on your special place: how can you reduce or stop them? Third, follow through with action. Alas, we concluded that all ecosystems require deliberate action now.
These 3As work from high-level government planning down to local land-care groups or even building a wildlife-friendly garden in your own backyard. We have reached that time where every tree is sacred, we must fight to retain every patch of bushland and, in some areas, we need to move species and create novel ecosystems.
There are exciting emerging concepts involved here too. Like ecological intensification that harnesses ecosystems services such as pollination to sustain adjacent agricultural production, while minimising the destructive effects of large-scale agriculture. Imagine a patchwork of agriculture with a lattice of connected nature – that’s of benefit to the farmers as well as the planet.
We can change course through these approaches, but the take-up is slow – too slow. And, of course, the elephant in the room is climate change. The most recent IPCC report concludes that global emissions must peak in three years to stay near the goal of only increasing temperatures by 1.5 degrees.
DURING THE AUSTRAL summer of 2019–20, while Australia’s east coast was on fire and Antarctica’s heatwave was developing, a virus was emerging in Wuhan. Brave Chinese scientists were sharing their knowledge on Twitter. Revisiting my messages to my family from Antarctica, I find a note sent on 28 January, three days after the first case of COVID-19 was detected in Sydney. I implored them to take the emergence of this new virus seriously, slowly stock up on food and face masks and avoid Sydney’s CBD. ‘Better to be prepared and it fizzles into a non-event than it becomes a pandemic and you are not prepared,’ I said. I could predict the potential of an invasive species’ gross patterns of behaviour because I had researched other invasive species.
In this way, scientists are effectively modern-day soothsayers: we join the dots first. The issue is whether the rest of the community is listening or – more to the point – willing to hear and learn. As this virus evolves, I worry about us dropping the ball on action such as basic community health measures – mask wearing, the rapid uptake of building air filtration. I worry about the lack of anticipation of increasing compounding pressures such as limited herd immunity and rising numbers of people with long Covid. I worry about the unwillingness of so many to be aware of the impact of hurt, pain and aggregated loss from such widespread death. And I loathe the micro-aggression of ‘it’s time to move on’. Rather, it’s time to double our scientific efforts and to listen and learn from our experts because the virus is constantly mutating, our immunity is waning and our under-fives are not yet vaccinated.
More than that, I worry about Covid being an exemplar of mass cognitive dissonance, and how such a pattern may apply to the even bigger challenge of our time: climate change. Because the collective joining of dots, by those thousands of tiny sparklers – including me – tells us we have no time to lose.
Those penguins, those seals who don’t care whether we exist or not; they are in the unenviable position of relying on us for their survival.
Between beginning and ending this essay (February–April 2022), more extreme weather wreaked havoc across the Southern Hemisphere. Corals have again bleached on the Great Barrier Reef; endless rain from Gympie to Sydney has left thousands of people homeless; a marine heatwave has reached from one side of the Australian continent to the other and stretched out to take in New Zealand. Subantarctic Macquarie Island has endured its hottest temperature ever (17 degrees), stressing seals and penguins. Another heatwave hit Antarctica, reaching deep into the continent with temperatures almost 40 degrees warmer than normal – but luckily still below zero. And at Casey, it rained on the mosses for two days.
By March, those mosses would have been freeze-dried and shut up shop for winter. We won’t know the impact of those rains until next summer – but we have done those experiments. Wake up frozen mosses with liquid water, and then freeze them. They are cactus, literally: the ice inside the mosses pierces their tiny cell walls and they die.