On Greenland and Svalbard, Arwyn Edwards studies cryoconite holes—dark pockets of soot, dust, algae and bacteria that can intensify melting. His work argues glacier microbes don’t just react to climate change: they can amplify it, while scientists race to samp
The darkness inside a glacier isn’t supposed to exist.
In cryoconite holes—small. sun-battered pockets drilled into the ice by soot. dust. algae and bacteria—dark material absorbs more solar radiation. Marco Tedesco of Lamont-Doherty Earth Observatory. part of the Columbia Climate School. has said. That extra absorption can mean faster melt. Arwyn Edwards has spent years returning to extreme cold places where this process doesn’t just happen in theory. It happens minute by minute, under instruments and gloved hands on the Greenland Ice Sheet and across Svalbard’s glaciers.
Edwards. a senior lecturer in biosciences at Aberystwyth University in Wales. trains his attention on some of the smallest inhabitants of glacier ecosystems: microbes. He studies how microbial interactions with the cryosphere shift as climate change forces glaciers to melt more rapidly—especially in the regions where the ice is changing fastest.
After completing a Ph.D. in microbiology at Aberystwyth, Edwards continued exploring the microbial biodiversity found within glaciers. One major focus became cryoconite holes, which he describes as complex glacial ecosystems that can accelerate warming and glacier melt.
Cryoconite holes form when dust settles on the ice surface and becomes colonized by microbes that can photosynthesize, including cyanobacteria. As cyanobacterial cells die. their chlorophyll breaks down and turns brown. reducing the albedo—the fraction of sunlight reflected by the ice surface. In turn, the ice surface melts and develops potholes.
The picture became sharper in a study Edwards says he is most proud of. Published in 2016, it investigated how cryoconite hole ecosystems respond when the system is pushed.
One member of Edwards’ team used a spoon to gather cryoconites from multiple holes and put them into a study hole. For a number of holes, the team “overloaded them with cryoconite,” then watched how the shape of the hole changed. By pairing that work with DNA analysis and biochemical analysis. the researchers could “eavesdrop” on what the microbes were saying to each other in chemical terms—captured in the sense that conditions had suddenly “gone dark. ” and the microbes needed to “grow out from each other and adapt to the low light conditions.”.
Edwards said the lesson was that microbes have intricate responses to environmental shifts, and that they appear most comfortable when spread out with space to grow. In his telling, the complex network of life interactions under extreme conditions makes the ecosystem unusually productive.
That work also sits inside a broader argument Edwards keeps returning to: these habitats may reduce albedo and drive melt, but removing cryoconite holes isn’t the answer.
When Edwards was asked how cryoconite holes reduce glacier albedo—and what the case is for conserving them despite their negative effect on the climate—he laid out the mechanism first. Glacier ice has a moderately high albedo. Put anything darker on the surface and the ice reflects less sunlight. absorbs more solar energy. and—if a thin layer of dark debris forms—transmits that absorbed energy efficiently to the underlying ice. Cryoconite holes, he said, therefore drive glacier melt rapidly.
Then he made the conservation case with equal force. The holes. he said. are extremely intricate microbial habitats home to thousands of species of microbes. and scientists know very little about the total biodiversity. He also pointed to potential human value in what those microbes might produce, including new antibiotics or enzymes.
But for Edwards the strongest argument is also the simplest: time is running out. He said his generation of researchers—and perhaps the generation that follows them—may be the last able to access this diversity on glaciers. because glaciers are going away across Earth at an unprecedented and scary rate. Without conserving these habitats. future scientists may lose both a subject of study and the chance to understand what that living diversity could still teach them.
That urgency has shaped more than the lab. In 2016, Edwards led what he described as the first polar night exploration of glacier ecology. In November 2016. the team carried out their first polar night work at a place on Svalbard they said they already knew—yet they ended up completely lost. The experience led Edwards to question how researchers could work safely and efficiently on a glacier during polar light.
He then wrote a research proposal to the Royal Geographical Society and became the first arctic and mountain research fellow in the society’s 200-year history. The project was called “In the Bleakest Midwinter.”
They returned to Svalbard to sample in polar light. They were able to collect cryoconite material and analyze its biodiversity to see how it changed over time. From there. Edwards said it spawned a larger project called Cryo 365. which he has led on Svalbard for a couple of years. looking at different seasons. His “punchline” was that “things are alive in the winter”—even when it is 24-hour darkness. extremely cold and snowy. life persists underneath.
But the field work itself is getting harder.
Edwards said Svalbard’s climate is warming at a rate seven times faster than the global average. For his research. that means everything has become urgent: it is urgent. he said. because researchers still need clear evidence of climate impacts in hopes of convincing policymakers that mitigation must happen sooner rather than later.
There is also the practical squeeze of time. Edwards said the team is running out of opportunities to collect samples to understand the environment. And the changing conditions are making fieldwork more dangerous and unpredictable, including increased polar bear interactions and rapid glacier melt.
He said he doesn’t believe scientists will ever generate enough evidence to convince everyone. Still, he believes efforts have to continue.
Underneath all of these projects—cryoconite experiments, polar night exploration, seasonal sampling—there is a single message Edwards wants readers to take with them.
Microbes, he said, are sentinels. In any ecosystem, they are the first to respond to changes in conditions compared with animals such as polar bears or reindeer. But they don’t just react. They also amplify climate change.
Edwards described multiple pathways for that amplification. One is the albedo reduction effect driven by darkening debris and cryoconite hole processes. Another is the release of greenhouse gases such as carbon dioxide and methane.
If microbes are “woken up” earlier and given fresh carbon sources to consume. he said they are good at producing more greenhouse gases. His take-home message is blunt: if microbes in the Arctic become active earlier. they can change the Arctic’s response to climate change—and that has consequences “for us all.”.
glacier ecology cryoconite holes Greenland Ice Sheet Svalbard microbes cyanobacteria albedo climate change methane carbon dioxide polar night Cryo 365