“A journey into the disappearing Arctic environment where spoon worms use their one-meter-long tongues to lick the seabed.”

James Parker February 3, 2024

It is currently summertime with an air temperature slightly below freezing. A fog has moved in, making it difficult to see the outline of the German icebreaker, Polarstern, which is anchored to a one-kilometre-long ice floe at a latitude of 85 degrees North. Next to a hole that was drilled through 1.4 metres of ice, Morten Iversen, who studies the movement of carbon in the ocean, has attached multiple plastic containers to a rope secured by ice screws. These containers will be left submerged in the water under the ice for a day in order to collect marine snow – clusters of dead algae and zooplankton waste that sinks from the surface of the ocean to the deep sea.

A group of biologists use a core drill to puncture the ice floe a short distance away. Their goal is to find algae that thrive under the sea ice, as these organisms are vital to the food chain in the Arctic Ocean. Once extracted, the ice cores, measuring one meter in length, are placed in plastic sleeves and loaded onto a sledge to be studied in the laboratories on the ship.

Daniel Scholz lowers a scientific instrument through an ice hole

A torpedo shaped scientific instrument is carried by a helicopter.

Frederik Bussmann, a marine chemist and PhD student at the Alfred Wegener Institute, measures the salinity at the edge of an ice floe

Emiliano Cimoli, a researcher at the University of Tasmania/Hobart, right, and Alfred Wegener Institute technician Erika Allhusen, drill an ice core to look for algae growing in and under the sea ice

A scientist is monitoring the area with a rifle hung on her shoulder and a flare gun attached to her belt. This location is known to be a polar bear habitat, although it is diminishing.

Our team is a part of a 100-person expedition, consisting of both scientists and crew members, that departed from the port of Tromsø, Norway in early August 2023. Our mission is to study the accelerating melting of the Arctic sea ice. Our focus is on understanding the impact on the marine ecosystem, including nutrient circulation, ice algae and plankton growth, and the communities of animals on the seafloor that rely on organic matter from the surface ocean.

An ice core drilled from sea ice in the central Arctic Ocean

The Arctic region is experiencing a significantly higher rate of warming compared to other parts of the world. The portion of the Arctic Ocean covered by sea ice during the summer months has decreased by approximately 40%, equivalent to 2.5 million square kilometers, since satellite tracking began in the late 1970s. The remaining sea ice is becoming thinner and there are fewer multi-year ice floes, which are chunks of ice that have survived at least one summer. A recent study suggests that the waters surrounding the North Pole could have little to no sea ice left by the end of summer as early as the 2030s.

The reduction of ice coverage has consequences beyond just the polar bears and seals losing their habitats. It also impacts the entire ecosystem that exists under the ice, including ice algae, zooplankton, and juvenile polar cod. These organisms rely on the cracks and crevices beneath the ice for food and shelter. As they grow, they become prey for larger predators like ringed seals and beluga whales. While thinner ice may allow more sunlight to reach the ice algae and increase productivity temporarily, the overall nutrient-poor central Arctic Ocean may limit this growth in the long term.

Planktonic algae, also known as phytoplankton, benefit from increased light availability and a longer growing season in the expanding open-water areas, according to data from satellites. This can lead to changes in productivity and a transition from ice algae to phytoplankton as the foundation of the marine food web, potentially having significant impacts on the entire ecosystem. In addition, the Arctic’s native plant and animal species are facing competition from invasive species such as plankton and fish, which are moving in from the Atlantic and Pacific as the oceans warm. However, predictions for the future of the Arctic Ocean are uncertain due to a lack of observation, which is why scientists are conducting research in this area.

A pelagic sea slug or sea angel (Clione limacina)

Antje Boetius, the lead researcher of the voyage, has spent 30 years studying the icy waters of the Arctic. Her team observed the lowest recorded level of sea ice in the Eurasian Basin of the Arctic Ocean during the summer of 2012.

The deep-sea ecologist and director of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, states that they are currently retracing their steps to redo previous measurements on the ice-ocean system until they reach the seabed.

The Arctic Ocean, covered in ice, is a largely unexplored area of our planet, particularly its deeper areas. In order to observe the larger animals living in the uncharted underwater mountains and abyssal plains, deep-sea ecologists have attached a camera system to the back of the Polarstern.

A polar bear explores the research area on an ice floe

The amount and variety of living organisms in this frigid, dimly lit and resource-limited habitat is truly remarkable: in certain areas, there are high populations of sea cucumbers and extensive communities of filter-feeding feather stars that can be seen in the light. We are amazed by sponges the size of basketballs dancing across the screens of the scientists, as well as apricot-colored anemones and star-shaped patterns surrounding the burrows of spoon worms, which use their one-meter long tongue to feed on particles on the seafloor.

The Polarstern ship frequently docks next to large floating chunks of ice, and a group of scientists venture onto the ice with heavily-loaded sledges carrying drilling tools and other equipment.

The expedition leader, Antje Boetius, on Polarstern’s bridge

Scouts use flags on bamboo poles to designate paths to various research locations. The ship’s helicopter flies above, carrying a torpedo-shaped sensor that measures the depth of the sea ice.

The pace of daily activities on the ship is based on the speed at which it navigates through the ice, the planned research expeditions, and the consistent meal times: breakfast at 7:30am, lunch at 11:30am, coffee at 3:30pm, and dinner at 5:30pm.

The researchers work non-stop, and often take advantage of breaks to rest after working long hours in the laboratory or outside on the deck in extremely cold weather. However, they make sure to also engage in social activities in the evenings, such as playing card games in the warm red lounge, playing water basketball in the ship’s pool, or participating in a trivia night at the bar.

Spotlights are used to steer Polarstern through the ice.

Despite the fact that there has been an increase in sea ice in the study area and the Arctic Ocean in 2023 compared to previous years, the expedition is progressing well. We come across thicker ice that is old and deteriorated, but the Polarstern is able to easily break through it, as well as encountering open water between the ice floes.

On September 7th, the ship effortlessly arrives at the furthest point north on the planet, the geographic North Pole.

This is the first time for most onboard, but for Polarstern it marks the seventh occasion. In 1991, the Swedish ship Oden became the first conventional icebreaker to reach 90 degrees north latitude.

According to Captain Stefan Schwarze, the Arctic Ocean has undergone significant changes since his initial voyage. He recalls that thirty years ago, they required two icebreakers to navigate through the pack ice, but now they can reach the north pole using only 30% of their engine power.