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On the frozen Arctic Ocean, high above the Arctic Circle, I’m searching for plastic.
I’m one of a dozen researchers standing on an immense floating ice sheet at 86° North. Freezing temperatures numb our fingers, limiting the movement of our hands, and the sun’s glaring reflection on the white ice is almost blinding. In these harsh conditions, even the simplest task becomes difficult – let alone the meticulous work of collecting samples.
I was invited to join an international team of scientists on their expedition, organised by the Institute of Polar Sciences of the Italian National Research Council. Their work focuses on the microbial ecology of the Arctic and Antarctic, and how microorganisms in these polar regions are responding to climate change.
Microorganisms are tiny living creatures, such as bacteria, fungi, and algae. They play a fundamental role in ecosystems, driving essential processes like nutrient cycling, decomposition, and supporting the food web. In polar regions, microorganisms can also help influence carbon storage, and contribute to the formation and stability of ice. Because microorganisms resiliently adapt to extreme environments, this makes them very useful indicators with which to measure changes to that environment.
In these incredibly remote locations, far from cities and any major human settlements, some polar scientists are trying to unravel a puzzle. Why are there high levels of plastic pollution in the ice, which outwardly still looks pristine? How did this plastic get there and what will be the impact on the Arctic?
An invisible threat
Plastic pollution has long been recognised as a problem in our oceans. Scientists find plastic in the stomachs of turtles who’ve confused your old shopping bag for prey, fish and other marine creatures become trapped in discarded fishing nets. But unseen, there is a far greater danger from plastic.
Think of the grains of sand on our beaches that used to be rocks in the ocean. In just the same way, plastic debris swirls and churns in the sea, gradually breaking down into ever smaller pieces. This degradation results in millions upon millions of fragments so tiny they can be hard to make out with the naked eye. Whenever these fragments get smaller than 5mm in size, they’re called “microplastics”.
Bracing against the Arctic cold, we drill a hole through the frozen ice. As one of the team guides a tube down into the exposed seawater, another turns on a pump and begins to filter the liquid. The aim is to extract the microplastics present and measure their concentration within the water found well-below the arctic surface.
Since these regions are isolated and far-away from human contamination, any pollutants we find must have been transported from other parts of the world. Plastics can be thrown into the rivers of cities, well inland, and make their way downriver, ultimately into oceans, where strong currents do the rest of the work. The much-eroded particles then scatter, and some go as far as the Arctic North, in the water beneath our feet.
But that’s not the whole story. We’re now realising that, due to their very light weight, microplastics can be transported over intercontinental distances, not just by waves, but by winds as well (and other atmospheric agents). It seems nowhere on Earth will be immune from the invasion of microplastic.
Back on the Arctic ice, the samples the researchers collected are taken back to our vessel, which has been left anchored between two broken ice floes a short distance away. While scanning the surroundings for any polar bears, the team protects the samples from the wind as if they were the most valuable thing in the world.
In the ship’s lab, a microscope reveals not just the microplastics as expected, but something else… the plastic particles have become home to a community of microorganisms.
Remarkably, clusters of microplastics can serve as welcome homes for microorganisms. They provide a stable, long-lived, and mobile environment onto which microbes can attach and grow. This plastic-based micro-ecosystem is known as a plastisphere.
The plastisphere hosts photosynthetic organisms, predators and preys, symbionts and parasites. It’s a fully working ecosystem that’s significantly different to the free-living microbial communities which we see form in nature.
Free-living microbial communities are exposed to many variables that influence their composition – temperature, salinity, pH, solar radiation, availability of nutrients, etc. In contrast, plastisphere-colonising communities have an extra layer of protection against some of these elements, thanks to the extremely solid and stable substrate they grow in.
The plastic of these microparticles acts as a physical barrier, shielding microbes from direct exposure to external factors. Microbes on plastic surfaces often form protective layers of cells and extracellular material – biofilms – that help protect them further. Even though these plastispheres are microscopic, they have the potential to alter the balance of many delicate ecosystems around the world.
It’s 2pm in the Arctic. After lunch, I’m heading to my room to have a quick coffee before going back to the lab. I sit down at the edge of my bed, looking outside the window. Out of the corner of my eye, I see something moving very fast, and I turn my head towards it. The creature perches on a floating piece of ice. It’s a Northern Fulmar, a heavy set bird that looks like a gull and is common in the Arctic. It’s majestic and beautiful but there’s something else about this bird that the casual observer can’t see.
For decades now, scientists have been finding microplastics in groups of Northern Fulmars. Within the research literature regarding microbial communities and plastispheres, authors have raised the possibility that one of these birds could ingest a microplastic particle which has been colonised by a dangerous virus or bacteria.
Not only could that threaten the creature that ingested it, but organisms higher up the food chain too - that infected bird could be consumed by a seal, which in turn is eaten by a polar bear. Microplastics could also be transported from one part of the world to another, potentially functioning as microscopic vectors for microbe-transport between ecosystems, carried (almost) invisibly on the wind. What if organisms in one region do not have the immune defences to combat new microbes invading from afar?
The ice is melting
Having finished our lab experiments for the day, we make our way across the deck to the common room - suddenly an almighty cracking sound echoes around us. All eyes turn to the glacier and we watch a colossal section of ice split and crash into the sea. I had just witnessed a ‘calving’, the formation of a new iceberg.
In the common room we begin to unwind. Although “common room” usually meant “break time”, we never really stopped talking about science, and as you might expect a major topic of our discussions was the melting of glaciers.
Although they look permanent, glaciers are changing all the time. In the Arctic, the base of a glacier is continuously exposed to seawater and gradually erodes until it can no longer support the overlying ice, ultimately leading to a collapse. That’s how icebergs are formed, as I had just witnessed outside.
Around the world, glaciers are melting. Human activity since the Industrial Revolution has driven this phenomenon, as carbon dioxide and other greenhouse gas emissions have raised global temperatures.
The Arctic is warming at a much faster rate than the rest of the world – a phenomenon known as Arctic amplification.
Arctic amplification happens when ice melts, and darker surfaces such as seawater or land become exposed. Instead of reflecting sunlight, these surfaces absorb it, which significantly speeds up the melting.
Studies have demonstrated the presence of microplastics in Arctic glaciers, meaning that as glaciers melt they liberate these particles into the environment. Moreover, trapped microplastics can themselves accelerate ice melting. These particles are often coloured, meaning that they can darken the snow cover or the ice by a few shades, further contributing to the Arctic amplification.
The Arctic is part of our world
When we think of the Arctic, we usually imagine a completely isolated, icy expanse. But this fragile ecosystem is home to indigenous communities who for thousands of years have relied on the land, sea, and wildlife of the Arctic to provide food and shelter. It seems grossly unjust that the irresponsible use of plastic can pose a threat to their native lands, when they’ve contributed so little to the problem.
A phrase used by a member of the team during our polar expedition repeats in my mind. “What happens in the Arctic, doesn’t stay in the Arctic.” This region is not a closed system. Everyday, tiny plastic particles are being released in the Arctic, and they will be carried on currents and winds to every corner of our globe. But what can we do about it? Scientists are racing for an answer.
