The Vanishing Arctic
Unraveling Biodiversity in the Face of Melting Sea Ice
The Arctic is a frozen home to iconic and vital species. It regulates our global climate and is home to four million people.
And it's melting.
Temperatures are Rising
The Arctic is warming about 4x faster than the rest of the globe.
This is called Arctic Amplification.
Surface temperatures are rising.
As temperature increases, sea ice melts.
This lowers the Earth's albedo, or the planet's reflectivity.
Lower albedo means the Earth absorbs more heat.
More absorbed heat means the warmer temperatures.
Warmer temperatures mean more ice melts.
And so on and so on...
This is a positive feedback loop.
Satellite imaging of the Arctic began in 1979.
Let's track the movement of ice:
In winter, new ice forms.
In summer, ice melts.
Some ice leaves the Arctic, traveling down the Fram straight and into the north Atlantic Ocean, where it melts.
Importantly, some ice survives the summer melt season and becomes multi-year ice - this is the good stuff (according to the animals).
Historically, enough ice is formed in the winter to replenish ice that melts in the summer.
Today, more ice is melting than surviving the summer and forming in winter.
This leaves the Arctic increasingly iceless, and the ice that is there is thin, unstable, young ice.
In addition to warmer temperatures, the melt season is getting longer.
That means ice is starting to melt earlier in the year and freeze later in the year.
The Arctic reaches it sea ice maximum around early March.
In 1979, the maximum sea ice extent was 16.3 million km 2 .
In 2023, it was 14.4 million km 2 .
The Arctic reaches its sea ice minimum in September.
In 1979, the sea ice minimum was 6.9 million km 2 .
In 2023, it was 4.37 million km 2 .
On the left is a 1985 satellite image of the Arctic in March, when sea ice is at its maximum after building up throughout winter; on the right is a satellite image from March 2021.
The difference in sea ice extent, particularly multi-year ice, is massive.
Why should we care?
The Arctic is a rapidly changing environment. Loss of sea ice will disrupt species across the ecosystem.
Biodiversity
Let's look at the unraveling biodiversity of the Arctic.
Climate change is vastly disrupting biodiversity across the Arctic. Environments are being altered, rearranged and destroyed. Biodiversity is being broken down along with ecosystem functions and services.
Every single species fills a niche in their environment. The breakdown of one species can have reverberations felt across the entire ecosystem. In an environment that is changing rapidly, important and iconic species are threatened everyday.
Understanding ecosystem responses to climate change and human activity is essential for conservation planning and management.
Lets Take a Walk Through the Arctic Food Web
Starting at the Bottom...
Sea ice algae
Sea ice is not barren.
It is a center of concentrated nutrients where small invertebrates, algae, larval fish, and Arctic Cod thrive.
Sea Ice Algae
Algae (phytoplankton anchored in place) begins to grow in spring when sea-ice melts, adding nutrients to the top layer of the ocean. Microorganisms use those nutrients to develop and algae spreads along the underside of the ice in long strands.
Phytoplankton
Phytoplankton begin to thrive in nearby, open water.
Zooplankton
Phytoplankton in turn support zooplankton, which range from single-celled organisms to jellyfish and small crustaceans. Zooplankton sustain all kinds of life, from Arctic cod to whales.
This interaction is only possible due to upwelling.
This starts when nutrients are poured into the Arctic Ocean from surrounding river deltas.
Those nutrients circulate in the ocean, eventually travelling from the seafloor to surface waters, where they support the growth of microorganisms.
This process occurs along continental shelves in relatively shallow water, as deep water limits the recycling of nutrients from the sea floor.
However, due to warming waters, sea ice is retreating to deeper, colder water.
With sea ice, goes the links in this rich ecosystem and the Arctic food web begins to unravel.
Fish
Arctic fish depend on sea ice as a vital habitat and shelter. A loss of sea ice means fish lose valuable spawning habitat, shelter from predators, and access to food.
Let's dive in to Arctic cod. They're an extremely valuable food source for many Arctic species.
Arctic cod
Arctic cod have the most northernly distribution of any fish. They range from 84 degrees north latitude and above.
The North Pole is at 90 degrees north latitude. So, Arctic cod are living at the very top of the planet.
That means there simply is no substitute for Arctic cod in the diets of some species, like ringed seals.
Artic cod within the crack and crevices of sea ice
Dwelling within the cracks and crevices of sea ice, Arctic cod depend on sea ice algae and zooplankton as an important food source. Sea ice also provides spawning habitat and vital protection from predators.
Therefore, a decline in sea ice means a decline in reproductive success for Arctic cod; this is a major disruption to Arctic food web.
Arctic cod "take a central role in linking the sea ice-associated and water column food webs to high level consumers.
Let's take a look at all the species that eat Arctic cod.
That's just a short list of all the animals that eat Arctic cod.
As we can see from the variety of species that depend on Arctic cod, the decline of this single species will have major reverberations throughout the Arctic, and likely beyond.
Marine Mammals
Left: Noatak the bearded seal; Right: Nayak the ringed seal
The Walrus
Marine mammals depend on sea ice for important life events, like breeding, giving birth, and raising pups.
Walruses depend on shallow waters to forage; they find food along the sea floor and can only dive to about 100m. They also need to haul out of the water between foraging trips to rest.
Historically, walruses haul out on sea ice to rest.
Due to the decline in sea ice, haul out sites are disappearing and herds of hauled out walruses are becoming more and more densely packed.
As sea ice declines, there simply isn't enough sea ice in shallow waters for walruses and their pups.
So, a new phenomenon is occurring. Walruses are hauling out on land in herds upwards of 30,000 strong.
This has never been observed before the last decade.
It's a significant change in behavior.
This also means that Walruses are forced to expend great amounts of energy to reach their foraging grounds and return to a place they can rest.
This means that they are exhausted when they finally reach land.
Walruses are easily spooked.
When a disturbance occurs, stampedes can arise quickly as panicked walruses flee towards the water.
During a stampede, pups are easily crushed to death by massive adults.
In 2017, the USFW found 64 walrus pups dead after a stampede on the Alaskan coast. All were under 1 year old.
Behind the scenes filming of Our Planet.
The Our Planet team was out filming in the field and captured this event when walruses climbed up a cliff to find free space to rest.
Due to the steep cliff and likely exhaustion from traveling, many walruses fell to their death.
Arctic Seals
There are six species of seals in the Arctic: harp, hooded, ringed, bearded, spotted and ribbon.
Three are entirely dependent on sea ice: harp, ringed, and bearded.
Left: juvenile harp seal; middle: ringed seal; left: bearded seal
Harp seals
Harp seals live at the sea ice edge year round, following the edge as it grows and melts.
Every spring, thousands of female harp seals gather on White Sea ice in northwest Russia to give birth to their pups.
Harp seals nurse their pups for about 12 days.
During this time, pups gain about 5 pounds a day. Everyday of weaning is vital in order for pups to reach a healthy weight.
Pups wean when they weigh about 80 pounds. After this point, harp sea mothers leave their pups on the ice.
Ringed seals
Ringed seals give birth on landfast ice (anchored to land) and sometimes drift ice (free floating).
They dig out lairs in the snow cover where they give birth and raise their pups - this requires thick layers of snow and stable ice.
Unlike the harp seal, ringed seals do not follow the sea ice edge throughout the year.
They stay on landfast ice, anchored in shallow water, along the continental shelf.
As we know, sea ice in shallow waters is disappearing.
Harp seal mother with her pup.
Early sea ice break up could disrupts seals' seasonal cycles and result in pups being prematurely separated from their mothers. This would lead to higher death rates for seal pups.
In addition, Arctic cod is a major food source for Arctic seals, particularly ringed seals.
Put it all together, and the only homes and only foods seals have ever known are disappearing.
We've arrived at the top of the Arctic food web
Polar Bears
Polar bears use sea ice as a platform and cover while hunting for ringed and bearded seals, their favorite foods.
They don't eat much in summers, as they wait for the return of the sea ice.
As sea ice declines and the iceless season gets longer, Polar bears are going longer and longer without eating.
While Polar bears are strong swimmers, they typically don't swim very long distances.
With sea ice decline, Polar bears are forced to swim great distances between ice and land.
The USGS followed one individual that continuously swam 426 miles over 9 days - without stopping.
This female bear was followed using GPS over two months on her search for hunting grounds.
Over the two months, the bear lost 22% of her body fat and her one year old cub.
Sea ice decline is pushing this keystone species to its breaking point. Climate change is quickly dragging this iconic animal down to extinction.
Sea ice decline is driving this majestic animal to starvation and exhaustion.
People in the Arctic
About four million people live in the Arctic.
About 10% are indigenous and they rely on local wildlife for subsistence.
Declining sea ice threatens Indigenous ways of life.
Bobby Schaffer: Iñupiaq elder, hunter, and scientist from Kotzebue, Alaska.
Indigenous communities in the Arctic have depended on bearded seals as a food source for generations.
Along with tribal elders and scientists from the University of Alaska, Fairbanks, Schaffer co-authored a study on the hunting season length for bearded seals.
The study found that, over the last 17 years, the hunting season has shortened by one day every year.
Kotzebue Sound, Alaska. The birthplace of Noatak the bearded seal.
In an interview with World Wildlife Fund, Schaffer describes the changes he has seen occur in his homeland within his lifetime.
By 2018 and 2019, Kotzebue Sound was ice-free all winter. And that had never happened before.
Schaffer adds that the bearded seals his community is able to catch are skinnier than they used to be and that dead seals are washing up on beaches because they have nowhere to go during storms and they drown in the ocean.
Read more about this study and Schaffer's experience here.
What Can We Do to Help the Arctic?
- Lower your carbon footprint.
- Consume and eat mindfully
- Oppose offshore oil drilling in the Arctic Ocean.
- Vote - use your voice!
- Spread the word - do your friends and family know what is happening in the Arctic?
