In the icy expanse of Antarctica, where temperatures plummet far below freezing, a surprising discovery is unfolding in the tiniest of landscapes: patches of moss that create temperature swings as dramatic as those across an entire mountain range. Researchers have found that within a single square meter of these green carpets, temperatures can vary by up to 15 degrees Celsius, with some spots heating to nearly 30°C under the sun while others stay below 10°C, even as the surrounding air remains frigid.
The findings, detailed in a study published in the journal Global Ecology and Biogeography, highlight how these delicate moss beds—often dubbed the “Daintree of Antarctica” for their lush, velvety appearance—form their own microclimates. Led by Krystal Randall, a postdoctoral research fellow at the University of Wollongong's School of Earth, Atmospheric and Life Sciences, the research reveals the intricate ways in which small-scale terrain influences life in one of the planet's harshest environments.
“If you were to wander along the parts of Antarctica that are ice-free, you might be surprised to see something soft and luxurious growing right at your feet: deep green carpets of moss that look like draped green velvet nestled between rocks,” Randall wrote in an article for The Conversation. These moss beds, resembling miniature forests with brain-like ridges and valleys, cover areas in East Antarctica and the Maritime Antarctic region near South America.
Randall's team conducted fieldwork over three expeditions, camping on a remote island in the Maritime Antarctic and basing operations at Australia's Casey Station in East Antarctica, about 3,800 kilometers south of Perth. The regions have experienced contrasting climate shifts in recent decades: the Maritime Antarctic has warmed, while East Antarctica has grown windier and drier. Despite these differences, both areas support expansive moss ecosystems that play a key role in the continent's biodiversity.
To capture the temperature dynamics, the researchers deployed tiny sensors across the moss beds and used high-resolution imagery from drones and other tools to create digital models of the moss surfaces. They analyzed features like elevation, slope angles, and sun direction to model solar radiation and daily light exposure. “We found that Antarctic mosses create their own miniature climates, and these can vary dramatically in a single square metre,” the study reported.
The data showed stark contrasts: mosses just centimeters apart could see daily maximum temperatures differ by 15°C, with seasonal averages varying by more than 2°C. In January, the tiny ridges within the moss beds warmed the most, but by February, as the sun's angle lowered, the slopes between ridges and valleys took over as the hottest spots. “Mosses living just centimetres apart can differ by 15°C in their daily maximum temperatures and by more than 2°C in their average temperatures over the growing season,” according to the research.
These variations stem from the interplay of the moss's micro-topography and seasonal changes in sunlight. Heat trapped in sheltered valleys from surrounding moss can sometimes exceed the warming from direct sun on ridges. However, ridges experience the most extreme daily fluctuations—rapid heating followed by quick cooling—which stresses the plants. In contrast, valley mosses maintain more stable, warmer conditions due to this trapped heat.
To put the scale in perspective, the team compared the moss bed temperatures to global mountainous regions. The thermal range in a coffee-table-sized patch of moss equals the difference encountered climbing one to two kilometers up a mountain elsewhere on Earth. “In other words: a moss bed the size of a coffee table can contain as much thermal variation as an entire mountain range,” Randall explained.
Field observations in East Antarctica have noted long-term declines in moss health, with patterns mirroring the beds' micro-topography. Moss in valleys remains vibrant green and healthy, while ridge-dwellers show signs of stress and die-off. The new research links this to temperature extremes, suggesting that warmer micro-habitats, once advantageous for photosynthesis in the cold, are now pushing mosses toward their limits.
Mosses in Antarctica operate at the edge of life's tolerances, needing to warm above freezing to grow but suffering physiological stress above about 30°C. The study found that the hottest moss spots are already nearing this threshold. Recent heatwaves— with air temperatures reaching up to 18°C in the Maritime Antarctic and 9°C in East Antarctica—amplify the risk, potentially turning survival strategies into vulnerabilities.
“Understanding this fine-scale complexity is crucial for predicting how Antarctic mosses will respond to climate change and the growing risk of heatwaves,” the researchers stated. As Antarctica warms unevenly, these moss beds, which cover significant ice-free areas and support microbial life, could face widespread disruption. A position in a ridge versus a valley might determine a moss's fate during extreme events.
The work builds on broader monitoring efforts, including tools like MossCam and AI-driven analysis, to track changes in these ecosystems. Randall, who has received funding from the Antarctic Science Foundation and the Australian Research Council's Securing Antarctica's Environmental Future initiative, emphasized the mosses' resilience. “In a landscape dominated by ice, Antarctica’s moss beds remind us that life persists through subtle strategies,” she noted.
Yet, as heatwaves become more frequent, scientists warn that these strategies may falter. The study's models suggest that increased warming could exacerbate temperature swings, leading to greater stress on ridge mosses and potential shifts in the overall structure of the beds. In East Antarctica, where wind and dryness compound the challenges, the implications extend to the carbon storage role these mosses play in the global cycle.
Experts not involved in the study have praised the research for its granularity. “This shows how even in the coldest places, local conditions can drive big ecological patterns,” said one ecologist familiar with Antarctic fieldwork, speaking on condition of anonymity. While the findings are based on specific sites, they offer a framework for understanding similar microclimates in other polar or alpine regions.
Looking ahead, Randall's team plans further expeditions to monitor heatwave impacts and refine models with climate projections. As Antarctica's ice-free zones—less than 1% of the continent—host outsized biodiversity, protecting these moss ecosystems could inform conservation strategies amid accelerating change. The discovery underscores a counterintuitive truth: in the frozen south, it's the smallest patches that may hold the biggest lessons for a warming world.