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The helicopter touches down on the sea ice at a landing site a few hundred metres from the ship. The group of scientists I have travelled here with heap their baggage and cargo on the ice, then we kneel around it with our heads down and hands over the bags, holding on tight to stop anything getting sucked into the helicopter’s draught as it takes off. I bury my face in my arms to protect my eyes from the fine snow crystals whipped up the wind as the rotors accelerate. When the noise of the engine fades away, we let go and uncover our faces to look around.

I have just arrived at an ice floe in the Central Arctic Ocean, a few hundred kilometres from the North Pole. The floe is a vast, thin crust of ice measuring about 2.5km by 3.5km (1.5 miles by 2.2 miles) across. For the most part, it is only 30-50cm (11.8-19.7in) thick. This piece of ice is the new home of the largest Arctic expedition of its kind, known as Mosaic, for the next year. Mosaic intends to form the most detailed picture yet of the Arctic environment, from the atmosphere to the ice and oceans, and the things that live there.

Several years in the past decade have reached new lows for summer sea ice extent, raising questions about what will happen in this new Arctic as the ice declines and retreats. How will the ecosystem respond? Can treaties keep fishing in the central Arctic in check? Is it possible for a ship to be present in the Arctic without polluting it?

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Climate change is transforming the Arctic fast, and there is a danger that by the time the scientists have collected and analysed their data, it could already be out of date. In the fortnight I have been away from this floe, reporting from another icebreaker involved in the mission, the team has been moving quickly to get the camp up and running.

The last time I was here, it was only possible to see white and grey ice in every direction. When scientists first explored the floe, they weren’t even convinced it would hold their weight. Now, a network of huts and colourful tents are connected by paths of compacted snow and slack copper-coloured cables propped up by short poles lashed together into tripods. Close to the helicopter landing site is a row of Ski-Doos (a type of snowmobile) with low wooden Nansen sleds hitched on the back. Allison Fong of the Alfred Wegener Institute, leader of Mosaic’s ecology team, marshals the small herd of new arrivals onto the sleds.

The team has switched gears since their arrival at the floe. I last saw Fong poring over maps in a plush blue carpeted room lined with glass cabinets, discussing the plan of the camp with the rest of the leadership team. Now she wears a shiny black ski helmet and goggles, a rifle slung over her shoulder in case of polar bears, as she drives a Ski-Doo away with four people in tow.

The Polarstern is a home away from home for the scientists studying the ice over the winter (Credit: Martha Henriques)

Much of the work by Fong’s team will take place in the “dark zone” of the camp. Up in the high Arctic, with no settlements for more than 500km (312 miles) around, light pollution might not sound like too much of a problem. But the ship itself is flooded with light from the decks and cabins at all hours. When I looked up hopefully from the deck one night in my first week on board, the stars were no more visible than they are in central London.

The dark zone, planned to be a patch of ice far away from the brightness of the ship, will be an area with strict controls on how and when lights can be used. Light has a strong effect on organisms living in the Arctic, whose biology is closely guided by the cycles of day and night – and at this latitude, night lasts for several months.

Light is not the only way the ship’s presence could interfere with investigating the Arctic ice ecosystem. The ship, as well as being the scientists’ home, workplace and life-support system in this dark and freezing place, is also one of their biggest scientific concerns. “It’s not so different from people who are trying to find life in space – they have to be careful about the fact that they’re shedding cells all the time,” says Fong. “We’re a primary source of potential contamination.”

When there is less sea ice in the Arctic, the ecosystem here stands to change profoundly

The ship’s waste water is another potential source of interference, says Fong. Polarstern’s waste water handling system has been modified for Mosaic. The water is cleaned and purified until it can be emptied into the sea. Known as “grey water”, this waste is typically released in a constant trickle from the ship at 5m below sea level. But that relatively warm, fresh water could disrupt the ocean physics and the living organisms nearby. The solution is to add salt back into the water before release, and pump it down through pipes to 150m. At that depth, it will be less likely to cause an issue.

The scientists are going to all this trouble to modify their ship to answer a barrage of questions about the Arctic environment, including how it has been affected by climate change. When there is less sea ice in the Arctic, the ecosystem here stands to change profoundly.

For the organisms at the very base of the food web, it most likely means a longer growing season due to less ice cover in the summer months, so more light can reach them. “This has huge implications,” says Fong. “It used to be that there was a very small fraction of the year that we had intense phytoplankton and sea ice algal growth.” Exactly what this change in growing season means is still an unknown. It could be that a longer growing season means more photosynthesis, more carbon drawn down into the food web, and more energy flowing through the Arctic ecosystem as a whole. But it might not be that simple.

Met City is a hub of warmth and light on the outer fringes of the camp (Credit: Martha Henriques)

There’s a question of whether or not these organisms are adapted to deal with the new conditions and the timing,” says Fong. “There may be mismatches of when phytoplankton grow and when there are animals ready in their life stage to graze on them.” The data Fong’s team is collecting could help discover how the altered Arctic growing season could affect larger animals, such as fish, seals and bears. For the latter, of course, the loss of their habitat on the ice could be the deciding factor.

Another mystery of the Arctic ecosystem that Mosaic is hoping to solve is about the fish that live here. A fish has never been found below a depth of about 25m in the central Arctic Ocean, as year-round ice cover has made this part of the world extremely difficult to access for both scientists and commercial fishing vessels. Pauline Snoeijs-Leijonmalm, professor of marine ecology at Stockholm University, Sweden, hopes to be the first person to catch one. As well as using hooks on a line descending from the ship, she will use echosounders and automated cameras to profile Arctic fish. On our way here she picked up a first tantalising signal on the echosounder that could be a shoal. “There they are,” she says. She suspects the fish are most likely to be one or two different species of cod, if the fish in the seas around the edges of the Arctic basin are anything to go by.

It’s much easier to go fishing in the Barents Sea and the Chukchi Sea, than coming all the way here for a few fish - Pauline Snoeijs-Leijonmalm

Snoeijs-Leijonmalm is an adviser to the European Union on an international agreement to prevent unregulated fishing in the Arctic high seas. As ice cover decreases and the idea of fishing here becomes less outlandish, there is growing interest in whether there are fish here and if so, if there are enough to tempt the fishing industry north. The agreement, which is between the EU, Canada, China, Denmark, Iceland, Japan, South Korea, Norway, Russia and the US, aims first to map whether there are many fish in this ocean and then to decide whether it would be possible to catch them sustainably.

But Snoeijs-Leijonmalm is doubtful that even the keenest fishing companies will want to visit any time soon. First, she doesn’t foresee there being many fish. “The central Arctic Ocean is very nutrient poor and very cold, so I do not expect a large biomass,” she says. “It’s much easier to go fishing in the Barents Sea and the Chukchi Sea, than coming all the way here for a few fish.”

Even if there were a sizeable community of fish, harvesting them sustainably would be extremely difficult. “I expect that we will find a very delicate food web,” says Snoeijs-Leijonmalm. “If you then take out the only fish that is abundant, you destroy the ecosystem.” This would cut off the food supply for seals and eventually bears, leaving little here but plankton. “It would be so stupid to destroy the system for some fish oil.”

An engineer peers into the “brains” of Met City – its data hub, lit by custom-installed fairy lights (Credit: Martha Henriques)

As we approach the central base with Fong by Ski-Doo, the dark zone that will be the site for much of the ecosystem team’s work is nowhere to be seen. There are still lights on all around the ship. The dark zone has yet to be established, as other more urgent priorities have taken over – not least the power cables connecting the camp’s “cities” or instrument hubs. The slack looping wires, covered with thick rime ice, have already had to be rescued from the ice more than once.

Nathan Kurtz, a physicist at Nasa’s Goddard Space Flight Center and part of Mosaic’s ice team, was on part of the crew setting up power lines to the Remote Operated Vehicle (ROV) site, a few hundred metres away from Polarstern. From here, researchers will deploy their ROVs on underwater surveys several hundreds of metres below the surface. But a small crack started eking open to become a broader lead of open water soon after the ROV site was established. “Initially we put the power cables pretty close to the lead. We weren’t thinking that it was going to expand,” says Kurtz.

I never realised how that little crack is such a big deal to the people that are on the ground – Nathan Kurtz

The next day, it began to look like the lead wasn’t stable after all. So Kurtz, whose usual job in the field is flying over the ice to make airborne measurements of its thickness, returned to the heavy work of shifting cables with the others. In the next days, the lead continued widening while part of the ice sheet started crushing into another to form a ridge. The team’s efforts to move the cable had helped, but the ice still did some damage. “Blocks of ice pushed the cable and buried it a bit,” says Kurtz.

After another team went out, they found the cable itself was still intact. It just needed to be retrieved and taken to what the team hoped would be a less vulnerable spot. After a few hours’ labour with ice axes, and the cable was soon retrieved. Even for scientists who have spent their whole career studying ice, realising just how much manual labour is involved has been a revelation. “I was thinking, ‘I’ve done a lot of flights over the Arctic ice and so I’ll get to see those same little cracks open up’,” says Kurtz. “I never realised how that little crack is such a big deal to the people that are on the ground.”

Unforeseen delays like this have not set the camp back too far. At the meteorological site, known as Met City, there are several instruments online and collecting data. I take another Nansen sled pulled by Ski-Doo out to the site, sitting behind Matt Shupe of the University of Colorado and leader of the Mosaic atmosphere team. He perches cross-legged in front of me as we are driven about half a kilometre from the ship to the site – a short but bumpy ride. Shupe tells me, “The front of the sled is actually the worst because –” But I find out why before he can finish the sentence, as we thump over a rut in the snow. It turns out to be quite some impact, and the front of the sled takes the brunt.

Scientists wait to leave the ice floe by helicopter, to travel back to the Akademik Fedorov (Credit: Martha Henriques)

Holding on tighter, we arrive five minutes or so later among the meteorological instruments spread out at the margin of a rugged and thick region of ice. This is the edge of the part of the floe that Shupe named the “fortress”, which seems to have stuck. The ice in that part of the floe is 5m (16.5ft)  thick in places, making it by far the thickest piece of ice that the expedition came across in its survey.

The centre of Met City is a plywood hut that stands on the newer part of the floe, which is around a metre (3.3ft) thick. Shupe points out an area in front of us that is ever so slightly darker than the rest. In the summer, this patch was a pond of meltwater where the ice had thawed. Much of the floe beyond the fortress is riddled with refrozen melt ponds like this, which are only around 30cm (12in) thick but will thicken through the winter.

But “city” is perhaps a grand word to use to describe the site. The centrepiece is a plywood hut, lit with a warm yellow glow that makes it look joyful and welcoming in the dark blue midday murk. The hut is wired up with power and a fibreoptic cable to transmit data back to Polarstern, and out to the wider world. Around the hut is a menagerie of grey metallic instruments all covered in a thick layer of rime ice. It’s a balmy -12C (10F) today, warmed by a thick blanket of cloud, but recently temperatures have been below -25C (-13F) for days, with wind chill making it feel like -35C (-31F).

Making these basic measurements of the radiative balance in the Arctic is so crucial to understanding climate change that the team has duplicated the instrumentation several times over

Beside us, one of the instruments makes a tinkling, blooping noise that sounds like a caricature of a cute robot in a film. It is a wind profiler, Shupe tells me, and that bloop is an acoustic signal it sends up to the atmosphere, where the sound is bounced back by the shifting air currents. Another instrument nearby, which looks like a giant metal zoetrope crossed with a windchime, is essentially a fancy bucket for collecting snow, to measure precipitation through the seasons.

Between these instruments is what looks like a high metal frame for a swing, but instead of chains and a seat attached to the central beam, there are two small megaphone-like structures. Their job is to measure incoming sunlight and infrared radiation from the sky, and how much is reflected from the snow below.

“Ultimately all of our energy for the Earth comes from the Sun. That’s our energy source,” says Shupe. “Climate change is all about putting more greenhouse gases in the atmosphere and changing the radiative balance – that’s the driver of it all.” That’s not to dismiss the enormous complexity of climate change, Shupe adds, with its many layers of interactions and feedback cycles between air, water, ice, land and vegetation. But at its core, it is down to the balance between radiation in from the Sun and radiation back out into space. Those factors are the really big terms in the equation, says Shupe: “The hammers, if you will.” Carbon dioxide emissions and other greenhouse gases have pushed these hammers off kilter, beginning the process of climate breakdown.

Blocks of ice build up at the side of Polarstern, a result of the ship crushing against the floe as it settles in (Credit: Martha Henriques)

Making these basic measurements of the radiative balance in the Arctic is so crucial to understanding climate change that the team has duplicated the instrumentation several times over. Several pairs of radiometers dot Met City, and they are distributed throughout the network of outposts tens of kilometres away from Polarstern too. If something happened to one of the instruments – like shifting ice or a curious bear – there will still be data to work with.

Indeed, one of the main pieces of instrumentation at Met City is a 12m (39ft) tower, which at present lies on its side next to a long, narrow crack. The fissure runs directly toward the tower from hundreds of metres away and then, at the last moment, takes a right-angled turn away from it. Shupe was working on the tower when the crack appeared, right beneath his feet. As a result, the tower, which is adorned with an array of instruments for profiling winds and radiation, has not yet been raised to the vertical. Beside it, the base has been constructed for an even taller meteorological mast, which will be 30m (100ft) high – the length of two buses – as soon as all the parts can be winched into place.

Unusually for this time of year, the winds have been blowing from the north, which has meant the floe has started drifting away from the pole

Although Met City is not yet finished, Shupe seems like he could not be more pleased with this blooping, ice-caked collection of instruments than if it really were a sprawling city his team had built.

Another brisk and bumpy Ski-Doo ride back to Polarstern and Markus Rex of AWI, expedition leader, shows me the trajectory of the drift so far on a screen in the Red Saloon, one of the ship’s common rooms. There is a pattern in the meandering line on the screen that shows one reason that cracks and pressure ridges have been appearing in the camp. “You see these cycles here?” he traces a line in the shape of a scalloped edge. “It’s fast here, then it’s always slow, slow, slow.” He stops at a pinch point on the line. “These are the points when we get the high pressure.” That’s when the floe is twisted and pulled in different directions.

At least there is some predictability in these cycles but still, but as Rex watches the screen inside the Red Saloon, it’s clear that there is little the team can do but hope the damage to instruments and infrastructure each time won’t be too great.

There’s another feature of the trace on the screen that has been bothering Rex more. Unusually for this time of year, the winds have been blowing from the north, which has meant the floe has started drifting away from the pole. This was not the plan, although the movements of ice are notoriously unpredictable. “Random motion has taken us to the south,” says Rex. “But sooner or later we will start to move northward.”

Polarstern needs to drift north not because the pole is of particular scientific interest on this mission, but because this trajectory offers the best chance of staying out of areas of difficulty. These are both physical and political – such as the Russian Exclusive Economic Zone, where the expedition does not have a research permit. Or there’s the Beaufort Gyre, which would trap the ship in a slow-moving circular current. Or worse, the ship could be swept into fast-moving currents that would take it too quickly into the Fram Strait between Greenland and Svalbard, risking an early break-up of the camp.

“That is just the way the ice drifts,” says Rex, looking at the colourful squiggle on the screen. Over a longer period, the floe is much more likely to begin moving north, following a similar route to floes in this region in previous years. “If it doesn’t, then the ice drift has completely changed and that would be very interesting, scientifically. But that is not going to happen.”

In some ways, the middle of the Arctic Ocean is as remote and otherworldly as it gets

Despite Rex’s conviction, the idiosyncrasies of the ice drift are not exactly reassuring to those who rely on them. The Norwegian scientist and polar explorer Fridtjof Nansen (who the sleds are named after) abandoned his ship, the Fram, during its 1893-96 drift expedition to the North Pole because the ice stubbornly drifted south instead of going north. In his frustration, he and a small team took to the ice on foot to try and reach the North Pole. They turned back at around 86 degrees north – about the same latitude we are at now – but still set a record for the most northerly expedition at that time.

In some ways, the middle of the Arctic Ocean is as remote and otherworldly as it gets. Scientists walk out on unknown floes that another human has never stepped on. They wear orange waterproof helicopter suits or red buoyant survival suits that make them look like they could be Martian explorers. They even move differently as the floe forces them into a strange gait, weight pitched forward in the wind and taking high, exaggerated steps through the deep, powdery snow. The ice, too, gives a good impression of the surface of another world – monochrome whites and greys out to the horizon, the only hint of colour the bluish tinge you get at dusk or, in the early days of polar night, a yellow-orange glow on the base of clouds, reflected from the Sun that sits below the horizon.

The helicopter departs the Polarstern, which will remain wedged in the Arctic ice over the winter (Credit: Martha Henriques)

The illusion is easy to fall for, but the pristine, untouched Arctic doesn’t really exist. Scientists and explorers have been coming this far north since Nansen, more than 120 years ago. Throughout much of the 20th Century, and once or twice in the 21st, Russian scientists drifted past the North Pole in rudimentary huts on a yearly basis to collect basic data. Besides the presence of people and ships, the broader influence of human activity has been pervasive here for decades, as our greenhouse gas emissions alter the composition of the atmosphere, pushing those “hammers” of the energy equation off balance.

The Arctic is still a wild and hostile place to be – try taking your gloves off – but it is not untouched. The influence of humans has altered it so much that the sea ice could soon be gone in summer, by some estimates as soon as the 2020s, writes Julienne Stroeve, a sea ice scientist at University College London and a participant in a later leg of Mosaic.

With the diminishing ice and the rising interest in shipping and the natural resources here – even the fish – the Arctic seems to have entered another runaway cycle. The less ice there is, the more interest people have in exploiting the region. “Now that the Arctic is opening, humans are going there more,” says Shupe. “We will want to utilise that space.”

Leaving the floe for the last time, I watch the blurry camp through the vibrating helicopter window. From the air the floe appears half-domesticated, its power lines run alongside fresh pressure ridges, linking an organised network of stations built on ice riddled with refrozen melt ponds, which in summer may be again studded with pools. It is the half that is still wild – the part where a well-camouflaged bear would be imperceptible next to a ridge, or where the floe could break unexpectedly and take part of the camp with it – that will be keeping these scientists busy throughout the rest of their year here.


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