Life in the deep freeze – the revolution that changed our view of glaciers forever

I’ve been fascinated by glaciers since I was 14, when geography textbooks taught me about strange rivers of ice that crept down yawning valleys like giant serpents stalking their next meal. That kernel of wonder has carried me through a career of more than 25 years. I’ve travelled to the world’s peaks and its poles to see over 20 glaciers. Yet, when I first started out as a researcher in the early 1990s, we were convinced glaciers were lifeless deserts.

Then in 1999, Professor Martin Sharp and colleagues discovered bacteria living beneath the Haut Glacier d’Arolla in Switzerland. It seemed that glaciers, like the soil or our stomachs, had their own community of microbes, their own microbiome. Since then, we’ve found microorganisms just about everywhere within glaciers, transforming what we thought were sterile wastelands into vibrant ecosystems.

So what’s all that glacier life doing? These life forms may be invisible to the naked eye, but they can control how fast glaciers melt – and may even influence the global climate.

The glacier microbiome

Just like people, glacier microbes modify their homes. When I first saw the melting fringes of Greenland’s vast ice sheet, it looked as if a dust storm had scattered a vast blanket of dirt on the ice. Our team later discovered the dirt included extensive mats of glacier algae. These microscopic plant-like organisms contain pigments to help them harvest the Sun’s rays and protect them from harsh UV radiation. By coating the melting ice surface, they darken it, ensuring the ice absorbs more sunlight which causes more of it to melt. In western Greenland, more than 10% of the summer ice melt is caused by algae.

Bright blue glacier ice on rocky terrain.
The margin of Engabreen glacier, Norway.
Grzegorz Lis, Author provided

Again, just like us, microbes extract things from their environment to survive. The murky depths of glaciers are among the most challenging habitats for life on Earth. Microbes called chemolithotrophs – from the Greek meaning “eaters of rock” – survive here without light and get their energy from breaking down rock, releasing vital nutrients like iron, phosphorous and silicon to the meltwater.

Rivers and icebergs carry these nutrients to the ocean where they sustain the plant-like phytoplankton – the base of marine food webs which ultimately feed entire ecosystems, from microscopic animals, to fish and even whales. Models and satellite observations show a lot of the photosynthesis in the iron-starved Southern Ocean could be sustained by rusty icebergs and meltwaters, which contain iron unlocked by glacier microbes. Recent evidence suggests something similar occurs off west and east Greenland too.

A microscope image depicting chains of brown rectangular cells.
Glacier algae from the Greenland ice sheet.
Chris Williamson, Author provided

But glacier bugs also produce waste, the most worrying of which is the greenhouse gas methane. When ice sheets grow, they bury old soils and sediments, all sources of carbon and the building blocks for earthly life. We think there could be thousands of billions of tonnes of carbon buried beneath ice sheets – potentially more than Arctic permafrost. But who can use it in the oxygen-starved belly of an ice sheet? One type of microbe that flourishes here is the methanogen (meaning “methane maker”), which also thrives in landfill sites and rice paddies.

A waterfall at the edge of a glacier.
Leverett Glacier’s wild river, Greenland.
Jemma Wadham, Author provided

Some methane produced by methanogens escapes in meltwaters flowing from the ice sheet edges. The clever thing about microbial communities, though, is that one microbe’s waste is another’s food. We humans could learn a lot from them about recycling. Some methane beneath glaciers is consumed by bacteria called methanotrophs (methane eaters) which generate energy by converting it to carbon dioxide. They have been detected in Greenlandic glaciers, but most notably in Lake Whillans beneath the West Antarctic Ice Sheet. Here, bacteria have years to chomp on the gas, and almost all of the methane produced in the lake is eaten – a good thing for the climate, since carbon dioxide is 80 times less potent as a greenhouse gas when measured over two decades.

We’re not sure this happens everywhere though. Fast-flowing rivers emerging from the Greenland Ice Sheet are super-saturated with microbial methane because there just isn’t enough time for the methanotrophs to get to work. Will melting glaciers release stored methane faster than these bacteria can convert it?

Within the thick interior of ice sheets, scientists worry that there may be vast reserves of methane. The cold and high pressure here mean that it may be trapped in its solid form, methane hydrate (or clathrate), which is stable unless the ice retreats and thins. It happened before and it could happen again.

Waking the sleeping giant

Despite the climate crisis, when I spend time around glaciers I’m not surprised by their continuing vitality. As I amble up to the gently sloping snout of a glacier – traversing its rubbly lunar-like fore-fields – I often feel like I’m approaching the hulk of an enormous creature. Sleeping or seemingly dormant, the evidence of its last meal is clear from the mass of tawny-coloured rocks, pebbles and boulders strewn around its edges – a tantalising record of where it once rested when the climate was cooler.

As I get closer, I catch the sound of the glacier’s roaring chocolate meltwaters as they explode through an ice cave, punctuated by a cascade of bangs and booms as moving ice collapses into hollow melt channels below. The winds off the ice play ominously in my ears, like the whisper of the beast, a warning: “You’re on my land now.”

The author inside a giant icy chasm within a glacier.
Exploring a frozen melt channel of the Finsterwalderbeeen glacier in Svalbard.
Jon Ove Hagen, Author provided

This sense of aliveness with glaciers changes everything. Resident microbes connect these hulking frozen masses with the Earth’s carbon cycle, ecosystems and climate. How will these connections change if we take away the frigid homes of our tiny glacier dwellers? These creatures may be microscopic, but the effects of their industry span entire continents and oceans.

After a period of uncertainty in my own life, which involved the removal of a satsuma-sized growth in my brain, I felt compelled to tell the story of glaciers to a wider audience. My book, Ice Rivers, is the result. I hope the memoir raises awareness of the dramatic changes that threaten glaciers – unless we act now.The Conversation


This blog is written by Cabot Institute for the Environment Director Jemma Wadham, Professor of Glaciology, University of Bristol.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Professor Jemma Wadham



Cancer and climate change


My Mother, Father, and I after my PhD Hooding in 2015


When I was growing up in Michigan, the man who lived across the street would tell me my dad saved his life. Walt and his wife were surrogate grandparents for my brother and I growing up; our grandparents lived across the country in California. Dad would always disagree about saving Walt’s life, try to deflect, talk about how it’s a team effort and he’s just one part. Walt was always insistent. 

My father is a world-renowned medical physicist. He works on how best to treat cancer with radiation, a pioneer in treating cancer in three dimensions. Hearing his colleagues talk about him, you can tell that he spent his career working primarily on two fronts: to make radiation treatment safer for both patients and the people who work with them, and to make that treatment more effective. My dad has spent his entire life harnessing a field of science with incredible destructive power to save people. 

Radiation physics started, in essence, with death. It was first self-inflicted, as prolonged exposure to radioactivity killed Marie Skłodowska-Curie, would have killed her husband except a horse-drawn cart got to him first, and killed her daughter and son-in-law. The Manhattan Project was primarily an output of the physics community, and that resulted in the deaths of tens of thousands. 


My drive to get into geology wasn’t high minded. I really liked Jurassic Park when I was a kid. That’s about it. I wasn’t trying to make money, wasn’t trying to save the planet, didn’t care about rocks, I just really really liked dinosaurs. The reason I liked dinosaurs, other people as well maybe, is because they capture our imaginations. They personify some narrative thread about the bizarre nature of past worlds. Giant reptilian creatures walking the Earth feels like a science fiction story, even though it’s simply science history.

Geology is at its best when telling stories. We can take people to weird locations, like the not-molten but constantly moving interior of the Earth. Amherst, Massachusetts, where I got my PhD, had a mile of ice on top of it in the geologically-recent past. We can tell you that where I grew up used to be a coral reef, if only millions of years ago. Dover used to be underwater and looked like the Bahamas. We use our stories, in paleoclimate, to unveil the past changes of Earth and put the future into context. Understanding the extinction that killed the dinosaurs and much of the other life on the planet, for example, helps explain how long it takes biodiversity to recover from severe and rapid events. Our science is experimental, only the experiments were run by the Earth long ago and we have to uncover what happened.


There’s a profound irony that radiation causes various forms of cancer in higher doses, and now is used to treat it. Radiation therapy essentially overdoses the cancer cells and causes them to die. If you don’t treat the cancer, which requires you to expose healthy cells, then there will be additional cancer.  There’s a duality there, or a careful balance between good (health) and bad (cancer). It’s unexpectedly poetic.

I, perhaps too hopefully and naively, view the development of radiation oncology as physics realizing it has profound tools it can use to heal. In its infancy physics used these tools for violent ends. Yes, people discuss a justification for the bombs being dropped at the end of World War II, but even if one accepts all of these arguments for their use without question, it remains a violent use of physics or radiation. I like to think that my dad, and his predecessors, his friends and colleagues, and those that will come after, chose to discard violence for healing. 


There’s a similar duality to geology – many of us embody it in the particular branch of geology that we study. I am a Micropaleontologist. That means that I study tiny fossils the size of a grain of sand. I’m more specifically a biostratigrapher and a paleoceanographer, among other things. Micropaleontologists in industry use microfossils to tell the age of sediments (biostratigraphy) or figure out what environments were forming, because the age and environment tell us a lot about if there’s oil in certain rocks. In academia we use those same tools to study the severity of past events to constrain the future. One side of the geosciences is extractive: it uses our stories to bring the past back. It brings fossil fuels to the surface. We rely on these fuels, and they’ve been important in the development of a variety of societies. It is, however, very clearly causing dramatic harm to our planet and our fellow humans.

Geology and physics are fundamentally different in a key way. Physics, at least Newtonian physics, is immediate. Throw a ball into the air, and it rises then falls. Start moving neutrons fast enough around Uranium-235 and it releases energy. Geology doesn’t have that sense of immediacy. Climate change is a slow-moving disaster. Each new generation is birthed into a time when the climate has already changed. It is perhaps not surprising that the general public doesn’t see this as a large problem. Living on human timescales, we only see some of the effects like larger storms.

Geology, however, should know better. We geologists know the rates of past changes in climate, and that CO2 is one of the most potent controls on climate. We have the long view of climate’s history, a view that encompasses billions of years. The stories that inform our future are hot and unpleasant.

I like to think that I’m on the right side with what I do. My research is on how a specific group of plankton (planktic foraminifera) evolve during past intervals of climate change, and I also use that same group to work on exactly how fast those past intervals of change happened. Even when all we want to do is talk about science at meetings, when I get together with other scientists we inevitably start talking about how to convince more people about the reality of increasing temperatures. I spent last year teaching in Texas and before that spent a year and a half at the Smithsonian National Museum of Natural History in Washington, D.C. doing frequent outreach programs. I spent a lot of time thinking about how best to reach folks who are hardened against hearing that the climate is changing and that it’s our fault. I spent weeks on my lectures when teaching climate science, going into the money, psychology, and politics of climate denial after spending days teaching about the physical science. I hope I’m not deluding myself when I say some of them changed their minds.


In a sense, Walt’s living past 50 was a direct consequence of my dad’s scientific output. I look up to my father. His scientific pursuits and those of his colleagues saved countless people from dying with cancer. Many of us have these choices, to work in a field or job that improves life on this planet, or, at best, continues a declining status quo. Do we build bombs, or do we save people from cancer? Do we make climate change worse, or do we use the past to educate people about our shared future? Science doesn’t operate in a vacuum. It’s easy to lose track of the human side of our pursuits.

My Dad and I playing our saxophones circa 1986

I understand the urge to go after a larger or stable paycheck. I have seen the house that having a hardworking and preternaturally lucky career in modern academia has earned me; it’s not a house it’s a flat, and it’s a rental so I can move every few months or few years. Despite that, my family has been lucky we’ve able to stitch together funding, and keep afloat through family loans when things get too tight. Others certainly don’t have that luxury. I’m from the United States, where we get our health insurance through our employers, and losing insurance is a constant concern when you have intermittent employment. I have a five year old daughter and am about to have another. Our five-year-old has lived in four different places: three states and another country, since she was born. One of the first things her teachers told us here in Bristol was “Wow, she adjusts to new circumstances fast.” She does, because the only permanency in her life are her parents and Skyping her grandparents and close friends from two moves ago. I continually reassess why I’m doing this. A big part of the reason is so that I hope both my daughters can look at me, and realize that I made the same choice my dad did.

My first daughter and I working on a microscope
while I worked at the Smithsonian Institution – National Museum of Natural
History in 2016

Dad had a moment in his life, when working on his PhD, when he wasn’t sure exactly what he wanted to do with his life. He asked my mother and she told him he should, of course, 

Help people. Do something good. 

He clearly took that to heart. 

This blog is written by Cabot Institute member Dr Andy Fraass from the University of Bristol School of Earth Sciences.

Andy Fraass