The Changing Face of Our Oceans Part 11: Arctic Meltdown

Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10

I keep meaning to finish this post series, but I keep finding new topics of discussion to address. Today we're going to talk about melting sea ice- and not in the way we usually discuss it in regards to sea level rise. (Which it doesn't even contribute to- land ice causes sea level rise, not sea ice. Icebergs, however, calve from land based glaciers for the most part, so they do contribute. Sea ice forms on the sea, and as such is just part of the water already in the ocean.) Instead, we're going to be discussing how the loss of sea ice is actually affecting oceanic ecosystems.

Polar bears are the most immediately visible victims of declining arctic sea ice. As the ice shrinks, polar bears are suffering more and more. This one is starving due to a lack of ice nearby to hunt from. [Image source]

The Arctic is the region currently seeing the most severe damage from man made climate change. The Arctic is warmer than it's been in 40,000 years. It's heating up at twice the rate of temperatures elsewhere on the planet. Each summer, more and more ice melts on average, and each winter, less and less new ice forms. As ice melts, it exposes ocean water, which absorbs over 90% of all incoming solar radiation, compared to ice's less than half, so the process is going to keep speeding up. As the sea ice declines, it's also resulting in larger waves forming in the Arctic (the sea ice usually suppresses them), which in turn break up more sea ice. Most climate change models predict ice free conditions (less than 1 million square kilometers of ice, which is a lot less than it sounds like- around the size of Egypt, most of which will be in the difficult to melt regions of the Canadian Archipelago) in the Arctic by 2040. Most models, however, are also notoriously cautious in their predictions.

So we're getting way more exposed ocean every summer. Who's it hurting? Well, first off- and most publicly visible- are polar bears. Polar bears are incredible swimmers, capable of traveling over a hundred miles to reach the sea ice where they hunt seals and other prey. Unfortunately, declining sea ice is resulting in patches of open ocean considerably larger than a hundred miles across. Polar bear drowning is turning into a real problem.It's not the biggest problem, however. As the ice cap begins to shrink and melt earlier in the year, polar bears are having to swim for shore earlier and earlier in the year, resulting in them having less time to store up fat reserves for the winter. The longer swims burn up more energy. The bears are starting to starve to death. The average weight of a female polar bear declined 60 kg (130 lbs) between 1980 and 2004.) This is forcing many bears to migrate southwards to find food instead- into human territory.

Melt ponds atop arctic sea ice. They're filled with freshwater that will eventually mix with the saltwater of the ocean when the ice melts all the way through. [Image source]

Polar bears aren't the only air breathing creatures threatened by the loss of their icy habitats. Arctic ringed seals are also dependent on sea ice. Despite their excellent swimming abilities, they do need to rest and sleep, and they do so atop sea ice platforms. In fact, they're the reason polar bears are there- the seals are the primary food source for the bears. Narwhals are also endangered by the loss of sea ice- they normally use sea ice to help themselves hide from their primary predator, orcas. Without it, they'll be easy lunch. Harp seals birth their litters on drifts of snow atop sea ice- if the ice has been thinned by melting, it's not unknown for the ice to break and dump the newborn seals into the water, where they drown.

The ice is also home to a much more unusual type of ecosystem as well. A sympagic environment is one dominated by ice. A surprising amount of life lives in the ice. Various species of algae grow quite happily on the bottom of the ice. The ice is also riddled with brine channels, which the algae and various bacteria and fungi thrive in. The algae, fungi, and bacteria are then consumed by copepods (microscopic crustaceans, annelid worms, and krill. All of the above are then consumed by creatures like the minke whale and various specialized fish. Loss of sea ice threatens the base of large parts of the Arctic food chain.

Krill feeding off ice algae. While this photo was taken in Antarctica, the same type of scene occurs all over the Arctic. [Image source]

The massive ecosystem disruption and change in the conditions of the Arctic open things up to another familiar threat- invasive species. Many native Arctic species, like the Greenland Shark, have evolved adaptations like slow metabolisms that better allow them to cope with the still fairly harsh conditions under the ice. As the ice retreats, the environment becomes friendlier to species that couldn't handle living under the ice, bringing them into competition with the specialized native species.

Of course, we haven't even addressed the most terrifying threat the heating up of the Arctic poses yet. The continental shelves surrounding the Arctic ocean are unusually wide, and average between 150 and 300 feet deep. Large quantities of methane hydrates are buried in the sediments atop the continental shelves. Methane hydrates are an unusual form of ice that entraps methane molecules. As the sea ice vanishes, the sea warms, and poses a real risk of letting large quantities of methane escape. Since methane is 23 times more effective than carbon dioxide at trapping heat, it'll grossly exacerbate the climate change problem.

An ice-covered fjord sticking into Baffin Island, the largest island in the Canadian Archipelago. This photo is taken in April, before the summer ice melt has seriously gotten underway. (The Arctic sea ice maximum usually occurs in March.) The Davis Strait, seen in the background, is estimated to contain 13% of the world's undiscovered oil deposits. [Image source]

Not all the human eyes on the melting Arctic sea ice are there for concern over disrupted ecosystems, however. A great many people are watching it for depressingly common motive- profit. As the sea ice clears, the dream of centuries is preparing to come to pass- the Northwest Passage will be opening. A sea route past the Americas to the North will be viable for the first time. This will allow cargo ships too large to fit through Panama Canal (even after it is widened)to travel from Europe to Asia more easily. The Arctic might eventually be opened up for offshore oil exploration as well- an ironic consequence of oil exploration elsewhere.

The downside of human use of the Arctic, of course, is that humans will be using the Arctic. We'll be carrying the same problems into the Arctic that we bring into other seas. Cargo ships will cause massive amounts of noise pollution, threatening cetacean populations. Oil spills will definitely happen, along with large quantities of trash and other pollutants being dumped into the sea. Fishing industries will spring up in the Arctic. Military conflict in the Arctic is a real possibility. We're likely to lose countless species in one of the least studied oceans of the world to our same old mistakes before we even get a change to meet them.

[Image source]

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Bibilography:

• The Ocean of Life: The Fate of Man and the Sea, by Callum Roberts
• https://en.wikipedia.org/wiki/Arctic_sea_ice_decline
• https://en.wikipedia.org/wiki/Arctic_ice_pack
• https://en.wikipedia.org/wiki/Sympagic_ecology
• https://en.wikipedia.org/wiki/Arctic_sea_ice_ecology_and_history
• https://en.wikipedia.org/wiki/Sea_ice#Relationship_to_global_warming_and_climate_change
• https://en.wikipedia.org/wiki/Polar_bear
• https://en.wikipedia.org/wiki/Ringed_seal
• https://en.wikipedia.org/wiki/Northwest_Passage
  https://en.wikipedia.org/wiki/Petroleum_exploration_in_the_Arctic
• https://en.wikipedia.org/wiki/Davis_Strait
  https://en.wikipedia.org/wiki/Baffin_Island
• https://en.wikipedia.org/wiki/Ice_algae
• https://www.theguardian.com/world/2017/mar/04/arctic-ecosystem-ice-disappear-ecosystem-polar-bears-fish
• https://e360.yale.edu/features/as_arctic_ocean_ice_disappears_global_climate_impacts_intensify_wadhams