Great Melt A New Effort to Understand the Warming Arctic
Nowhere is the globe warming as fast as in the Arctic, where ice is rapidly disappearing. Now, researchers have embarked on the biggest polar expedition of all time, with the goal of untangling the complex dynamics at play.
Markus Rex fondly remembers the time he and some colleagues sped across a frozen fjord at 120 kmh (74.5 mph). He points to a picture on his computer screen of a snowmobile atop a field of snow, the whiteness stretching as far as the camera's lens could see. "March 1992" is written in the upper left-hand corner. In the foreground, to the right, is a giant block of gleaming, blue ice. "That was fun," Rex says.
But joyrides like that are a thing of the past. They have been for a while. "Today, springtime at our research base at the Kongsfjord on Svalbard looks like this," says the polar researcher from the Alfred Wegener Institute (AWI) in Bremerhaven, Germany. He clicks on a second photo. "Open sea," Rex says. Only a few pieces of floating ice are visible. A pair of eiders has taken refuge on one of them. Over the course of his 25-year career at the AWI, Rex has melancholically observed how the sea ice has disappeared in Svalbard, year after year.
Climate change has taken a devastating toll on this region, and it hasn't taken long. As much as the various computer forecasts differ from one another, all come to the same conclusion about one thing: Thanks to the man-made greenhouse gas effect, nowhere on the planet are temperatures rising as quickly as they are in the Arctic.
As a rule of thumb, researchers expect temperatures to rise by about 1.5 degrees Celsius (2.7 degrees Fahrenheit) per decade. In the winter, they expect temperatures to rise by as much as 3 degrees. "In order to make climate change tangible in Europe, you have to look at statistical averages," Rex says. "Up here in the Arctic, all you have to do is look out the window."
And yet it is precisely where the planet is warming most rapidly that there exists the greatest uncertainty. "Nowhere is the fickleness of the climate prognoses as striking as in the Arctic," Rex says. Will climate change warm up the polar region by 5 degrees Celsius by the turn of the century, or will it be 15 degrees? "We don't know," Rex says.
A Historic Mission
The difference between the two scenarios is enormous. But as paradoxical as it may seem, there is surprisingly little data available on this particular aspect of climate change. "The processes in winter, in particular, are practically unresearched," Rex says. That's why, eight years ago, he and a colleague decided to take a closer look at the polar night and forged plans for an ambitious research mission.
It sparked considerable interest. Colleagues from a wide range of research disciplines were eager to take part. By the time they had hashed out a formal concept for their project, which they called "Mosaic" -- Multidisciplinary drifting Observatory for the Study of Arctic Climate -- the mission had grown into a megaproject.
On Friday, Sept. 20, the Polarstern, a German research vessel, set off from Tromso, Norway, for the largest Arctic expedition of all time.
It involves research organizations from 19 different countries and some 600 scientists. These include oceanographers and marine ecologists, atmospheric physicists and biochemists, glaciologists and climate researchers.
Their measurements will supposedly help them better understand the dynamics of the widespread melting that is currently taking place at the North Pole. Year after year, scientists anxiously ask themselves the same question: How much will the ice cover shrink this time? Will the record low seen in 2012 be beaten? Or will the sea ice withstand the summer sun and greenhouse heat better this year?
A Guessing Game
This last winter, as happens every year, the ocean froze all the way to the coasts of Russia, Alaska, Canada and Greenland. In summer, the ice then retreated and polar researchers from around the world practiced predicting the extent of the meltdown.
People from the AWI are among the scientists taking part in the yearly guessing game. The climatologist Monica Ionita plays the role of admonisher. "This year, the ice will be exposed to powerful attacks from above and below," she says. Not only will warm water from the Atlantic flow far in the direction of Siberia, a heat wave in late July also melted a record amount of ice in Greenland. "It's as if nature is conspiring against the Arctic," Ionita says.
She is especially worried about the jet stream, as the powerful currents of air that encircle the polar region and blow in a counterclockwise direction are known. They keep the cold in the north and seal it off from more temperate regions closer to the equator. But as the difference in temperatures between north and south disappears, the jet stream gets weaker. Every now and then, it fluctuates to the north or south.
This can cause cold spells in Europe, while also allowing warm air to penetrate the polar region. It's a vicious circle that reduces the difference in temperatures between north and south even further, making the jet stream even more unstable. And on and on it goes.
"People always ask me, 'Why do you care what happens at the North Pole?" Ionita says. "They disregard the fact that our weather system is linked to the Arctic, via the jet stream."
Ionita's colleague at the AWI, Frank Kauker, is on the other side of the weather forecast rivalry. Reality, he says, is more complicated than the oversimplified notion of a climate catastrophe would lead us to believe. "The volume of sea ice in the Arctic even increased over the last few years," he says. And nobody knows why.
But even Kauker has no doubt that the ice in the Arctic Ocean will disappear in the long term. "The question isn't whether summers at the North Pole will be ice-free, but when," he says. Some climate forecasts say 10 years, other 50. "This gives us an idea of just how ignorant we still are," says Kauker.
A Modern Research Icebreaker
In order to close these knowledge gaps, the Polarstern crew will penetrate the pack ice north of central Siberia and drop anchor at a large floe, allowing themselves to be frozen in over the winter. Firmly surrounded by ice, the ship will then drift with the maelstrom first toward the North Pole then westward, before being released by the ice next summer in the Fram Strait, somewhere between Greenland and Svalbard.
"The logistical challenge is enormous," Rex explains, even though his team won't be the first to piggyback on the ice for a journey through the polar night. The first pioneer to embark on such an expedition was the Norwegian Fridtjof Nansen, who at the end of the 19th century, commissioned the construction of a special wooden ship -- the Fram -- to prove the existence of transpolar drift. Later, Soviet and Russian scientists also set up camp on moving floes, where they carried out meteorological measurements.
But they were only the vanguard. The Mosaic team intends to establish a sprawling research facility on its ice floe. "For a long time, no one thought such a thing possible," Rex says. The fuel supply alone is anything but easy. Even in the winter, when the Polarstern's engine only runs as a generator, it guzzles 15 tons of fuel a day -- not exactly the most environmentally-friendly rig.
There has never been a sea ice laboratory like the Mosaic team hopes to set up. The plan is for a network of paths on the ice floe to connect all sorts of probes, measuring stations and research equipment. The researchers have also discussed, if necessary, cutting a runway for supply planes into the ice.
Once the infrastructure is set up, atmospheric researchers will send sensor-equipped balloons into the night sky. Using radar and infrared devices, they want to probe the clouds, tracking and measuring atmospheric currents of heat and air.
Meanwhile, biologists and oceanographers will drill holes in the ice through while they will drop cameras, probes and drones. In addition, a hole in the Polarstern's hull, known as a "moon pool," will provide the scientists with direct access to the water.
North Pole Ice
The sea ice itself must also be studied. It's crossed by a vast network of tiny channels carrying salt water. This delicate system of drainage can change depending on the temperature and weather, affecting the salinity and thermal conductivity of the ice.
"The flow of heat through the sea ice is one of the great unknowns in the Arctic climate," Rex explains. The heat flow determines how much new ice can accumulate on the bottom of floes, but it also affects how strongly the ocean and the atmosphere are connected.
"The air temperature in winter drops to minus 45 degrees," Rex says. "Compared to that, the ocean water is almost hot." How well can an ice shelf shield this heat? And what role do heat leaks play when sudden fissures appear in the sea ice? All this is what the researchers hope to find out.
On his computer, Thomas Krumpen plans the Polarstern's route. The sea ice physicist from the AWI can set the wintry drama of the Arctic into motion with a couple of clicks. The simulation, pieced together from observational data from remote sensing satellites, shows the cycle of formation and decay of sea ice.
It depicts how offshore winds drive the ice from the Laptev Sea toward the pole, causing large, dark areas of open water to form off the coast of Siberia. Here, where cold air from the Arctic directly touches the much warmer surface of the sea, is where the ice at the North Pole is born. Huge amounts of water freeze and are then promptly transported north.
An Optimal Drift
Krumpen's simulation also shows how the white crust shifts westward. A large chunk of ice moves, slowly accelerates, passes the North Pole heading toward Greenland and is finally pushed out from the island's eastern seaboard into the North Atlantic.
Another piece of ice drifts beyond the North Pole along the Canadian coast, where it is captured by the mighty vortex of the Beaufort Sea, from which the ice moves back into the northern Arctic Ocean and often circulates for years.
Krumpen's dynamic simulations are very important for the Mosaic expedition, since they determine where the Polarstern can find the best floe for its winter mission.
The researcher shows colorful lines crossing over the pole on his screen. "These are the routes that individual ice floes have followed in the past," he explains. Depending on which starting point he selects, very different pictures emerge. His job is to identify points in the Arctic Ocean that are most likely to offer an optimal drift.
Under no circumstances may the Polarstern begin its winter journey too far northeast. This would put it at risk of getting sucked into the Beaufort vortex. It would be just as bad if the drift pulled the ship too far south. There, it could wander into Russia's territorial waters. "That would be the end of the mission. We don't have a research permit there," Krumpen says.
Krumpen has other instructions to follow as well: The Polarstern shouldn't spend too much time near the North Pole, if possible. This is a blind spot for most satellites. "Mosaic is supposed to collect data that we can cross-check with observations from space," Krumpen explains. "But that's only possible when we're in the satellites' field of view."
With so many specifications, finding the ideal berth for the Polarstern won't be easy -- and climate change isn't making Krumpen's job any easier. This summer, the pack ice in the Laptev Sea retreated farther than almost ever before. Large, stable floes are a rarity. "There's hardly any ice left that's more than a year old," Krumpen says.
For this reason, the Mosaic researchers assume the search for the perfect mooring spot will take some time. They will have to send out helicopters and reconnaissance teams and then cross-check the measurements they receive against satellite photos. "This first phase is crucial to our success," Rex says.
The Arctic Cod
If the Arctic ice cover shrinks, it could have serious implications for fauna. Hauke Flores, a biologist with AWI, is one of the people whose job it is to worry about this kind of thing. At the center of his attention is a small fish with big significance: the Arctic cod. It's a relative of the Atlantic cod, but unlike its cousin, it only grows to be about 30 centimeters long. It populates the northern Arctic Ocean in huge shoals; indeed, it is the most common fish there. "The Arctic cod is the herring of the Arctic," Flores says.
For many sea birds, beluga whales, narwhals and ringed seals, the Arctic cod is an important source of food, making signs of the species' decline all that much more alarming. If the Arctic cod disappears, the polar food chain could collapse. Flores speaks of "disruptive changes." The way he sees it, it's his duty to document an ecosystem that soon may no longer exist in the same form.
Flores' fears are still only based on hypotheses, at least so far. The circle of life that exists under the thick slab of drifting Arctic ice remains, to a large extent, a mystery. The Mosaic expedition should help the researchers gain more clarity.
Seven years ago, Flores was fishing with a special net that could reach underneath the edge of the pack ice. He caught an enormous amount of young Arctic cod.
Shielded from the cold by anti-freeze properties in their blood, the young, finger-long fish seek refuge in cracks in the ice. As their shelter moves, so do they; together, they wander through the Arctic Ocean. "We assume that the ice drift is responsible for the spread of Arctic cod," Flores says.
An examination of the contents of their stomachs revealed that the young Arctic cod feed mainly on tiny shrimp. This allowed Flores to reconstruct the spectacle that repeats itself every year when the Arctic awakens after the long polar night: The light touches the Arctic algae, allowing it to blossom. The shrimp eat the algae, and the cod eat the shrimp.
Now, however, this process is in danger of grinding to a standstill. If the ice retreats to the north, that would mean that the polar night would last longer at the edge of the ice shelf. As a result, the algae would have less time to grow, disturbing nature's delicate schedule; the Arctic cod, for their part, could hatch before there's enough food for them to eat.
The Arctic Is Facing a Catastrophe
While the young Arctic cod are threatened by potential famine, the larger, adult fish face a different kind of pressure: Along with warm water from the Gulf Stream, capelin and Atlantic cod are increasingly making their way into the Barents Sea, which has historically been the dominion of the Arctic cod. Now, the native fish must compete with the new arrivals for the same resources. And the warmer the water gets, the more the Arctic cod are pushed back.
The Arctic is facing a catastrophe, Flores says. He uses the word in the neutral, unprejudiced way that biologists do. "We understand it to mean the extinction of a species, as many have experienced in the history of the Earth," he says. This would in no way mean an end to life in the Arctic. "On the contrary, if the North Pole remains ice-free in the summer, there could be more life there than ever."
The biological diversity, however, would dwindle. "The species that are now immigrating already exist. Therefore, they don't contribute to an increase in global diversity," Flores explains. "The species that are displaced, however, will be lost forever."
Just how advanced this catastrophe is can be surmised based on records kept by Nansen, the polar pioneer. The Arctic world he encountered on the Fram in 1893 no longer exists. He couldn't even sail as far north as Novaya Zemlya in July before running into closed ice. "It stretched everywhere, as far as the eye could see," Nansen wrote. Today, at the same time of year, cargo ships pass through the area on their way from China to Europe.
Even later, when the Fram was surrounded by winter ice, Nansen's crew was exposed to forces that the Mosaic team will be unlikely to encounter. The 18th-century explorer described how, as they lay in their beds, the ice outside would "thunder and crack as if Judgement Day had come." Today, the ice still cracks when pushed together by the tides. But the thundering -- that raw, elemental force -- just isn't the same.