“It felt really scary … like being in the middle of a burning city during a night raid.” Dr Arwyn Edwards is not recalling warfare, but a sweltering, foggy day on a Svalbard glacier, when record-breaking summer heat transformed his workplace into torrents of meltwater and showers of falling rock.

Edwards is a leading figure in glacier ecology – the study of the life that survives on, within and around glaciers and ice sheets. After two decades in the polar regions, he has always felt “relaxed and at home” on the ice. But accelerating climate breakdown is eroding that sense of security.

Although average global temperatures have yet to breach the 1.5C Paris threshold, the Arctic surpassed it long ago. Svalbard is warming at seven times the global average.

Time is running short to study these fragile ecosystems and the trillions of dollars’ worth of climate costs they could unleash.

Edwards calls the cold-adapted microbes he investigates “the watchkeepers and arch-agitators of Arctic demise”. Research shows that snow- and ice-dwelling microbes contribute to positive feedback loops, accelerating melt. With over 70% of the planet’s freshwater stored in ice and snow – and billions of people reliant on glacier-fed rivers – the implications are global.

Yet not all microbes hasten warming. Some populations appear, for now, to help suppress methane emissions.

Until recent decades, scientists assumed Arctic ice was largely barren. On Longyearbreen, a glacier near the world’s most northerly town, Edwards digs through layers of last winter’s snow to demonstrate how wrong that was.

Edwards notes that all fresh snowfall contains microbes and, remarkably, microbes themselves can trigger snowflake formation. Each cubic centimetre of snow contains hundreds to thousands of living cells and roughly four times as many viruses, creating a habitat as intricate as topsoil.

“The organisms that can survive here are very, very evolutionarily advanced,” Edwards says.

In summer, the snow surface can bloom with red-pigmented algae, which swim through the layers in search of sunlight, creating the crimson sheen known as “watermelon snow” or “blood snow”, noted since Aristotle.

Beneath, solid glacier ice hides further life: microbes that endure sub-zero temperatures, near starvation, and endless cycles of darkness and light. Embedded within are “cryoconite granules” – dark, soil-like clumps that have been dubbed the “frozen rainforests” of ice.

“If I look at a glacier surface, I don’t see ice. I see … a three dimensional bioreactor,” Edwards says.

Each is a self-contained ecosystem of bacteria, fungi, viruses, protists and even tiny creatures such as tardigrades and worms.

These communities influence the planet at scale, yet many glaciologists still dismiss them as “impurities”. “Oceanographers would not treat fish in the sea as impurities,” Edwards remarks.

Microbes in surface ice produce dark pigments to harvest sunlight and shield against UV, while also trapping soot and dust. Together, these processes darken the ice, increasing heat absorption and melt – a phenomenon known as “biological darkening”.

They also respond to global changes. Extra nutrients from air pollution, wildfire smoke and dust from shrinking glaciers fuel their growth. “Snow chemistry today is not what it was in the pre-industrial era,” Edwards notes. Rising temperatures and longer melt seasons accelerate the process further.

This creates a feedback loop: ice-darkening microbes speed up melt, exposing more debris, which in turn nourishes more microbes that further darken the surface. Each summer, a darkened zone covering at least 100,000 sq km appears on south-west Greenland. A 2020 study found microbes there cause 4.4 to 6.0 gigatons of runoff – up to 13% of the ice sheet’s annual melt, from a mass that holds enough water to raise sea levels by more than seven metres. These effects are acknowledged in IPCC reports but are not yet built into climate models.

Across the Himalayas, Alps, central Asia and beyond, at least 2 billion people rely on glacial meltwater. Even if Paris targets are met, half the world’s glaciers will vanish this century.

Methane poses another danger. Glaciers and permafrost cap enormous reserves of the gas, preventing its release. But microbes thriving beneath glaciers can also generate fresh methane. As ice retreats and permafrost thaws, unexpected emissions are emerging.

Across the fjord from Longyearbyen, Professor Andy Hodson of the University Centre in Svalbard shows how groundwater surging through frozen ground forms “pingos” that release methane-saturated water. Yet he and colleagues have also identified microbial communities there that consume methane, out-competing producers. Methanotrophs will not eliminate emissions everywhere, but without them the problem would be worse.

Estimates suggest Arctic feedback loops could add $25–70 trillion to global climate costs.

On Foxfonna, a central Svalbard glacier, Edwards points to ice lying four metres lower than last summer. Since his first visit in 2011, the glacier has shrunk dramatically.

Like animal bodies, glaciers host their own microbiomes, sometimes harbouring species found nowhere else. Searching in vain for a microbial habitat lost to melt and erosion, Edwards likens the loss to marine biologists watching coral reefs bleach and die. These snow- and ice-dwelling species hold not only scientific and intrinsic value but also untapped economic potential. Their genetic adaptations to extreme cold, darkness and nutrient scarcity could inspire medical, industrial and environmental innovations. With each year of warming, society loses more of this resource.

Edwards has called for an international repository to preserve polar microbial diversity, modelled on Svalbard’s Global Seed Vault.

Visitors flock to Svalbard for its wildlife, which remains abundant – for now. On a boat trip into a fjord, more than 80 beluga whales appear. Yet their survival also depends on microbes: whales eat fish that feed on plankton, which rely on glacier-derived nutrients – partly controlled by the very microbes Edwards studies.

It is a reminder that microbes are not just drivers of ice melt and climate feedbacks. They underpin whole ecosystems. Without them, abundance would collapse.

Edwards compares his work in the Arctic to visiting his father, who suffered from vascular dementia: with every visit, something more was lost.

“It’s a step-by-step progression,” he says. “You wouldn’t see it dwindling day by day.”

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At Natural World Fund, we are passionate about restoring habitats in the UK to halt the decline in our wildlife.