Walruses are best known for their characteristic tusks and blubbery physique. They spend most of their time in the open ocean hunting for crabs, clams, and sea cucumbers. In between hunts, the 2,200 pound pinnipeds rest on sea ice floes.
In 2015, residents of Point Laye, Alaska, reported sightings of up to 40,000 walruses that crowded ashore on the small barrier island. The walruses were forced ashore by the lack of sea ice that they and other marine mammals depend upon for birthing.
Since the year 2000, mass walrus strandings on barrier islands have become increasingly common as climate change reduces sea ice cover in the Arctic. Unfortunately, walrus strandings are just one of many troubling symptoms of a larger problem. Throughout the Arctic, sea ice loss and rising temperatures are contributing to a series of ecological changes including increased acidification, massive species die-offs, and shifts in the migratory patterns of fish.
Rising temperatures have caused a 50 percent decline in Arctic ice cover over the past three decades. Though the planet has warmed about 0.8 degrees Celsius over the past forty years, the Arctic has been warming twice as fast. While rapid Arctic warming speeds sea ice loss, diminished ice cover also ramps up Arctic warming in a dangerous feedback loop. When the Arctic Ocean loses its reflective coating of white ice, the darker color of exposed ocean waters causes the region to absorb more heat from the sun’s rays.
Decreased ice cover also means greater uptake of carbon dioxide by large swaths of previously inaccessible ocean, causing warmer temperatures and shifts in ocean chemistry. Rising pH levels are particularly dangerous for shellfish and other calcifying marine organisms that are unable to build their shells in acidic water that contains fewer calcium ions. Ocean acidification has the potential to negatively impact 32 percent of calcifying species and alter the delicate balance of the aquatic food web.
Scientists are also concerned that ice loss could cause large-scale consequences for ocean circulation patterns, such as the Atlantic Meridional Overturning Circulation, a major ocean circulation system that acts like a conveyer belt, carrying warm water from the equator to the poles and bringing cold water back to the tropics. The shrinking temperature gradient between the rapidly warming Arctic and the tropics could disrupt this circulation pattern, which could impact sea levels in the Arctic and trigger unknown consequences.
On land, Arctic communities that depend on year-round sea ice cover for shelter, trade, and hunting have shifted food sources, altered traditions, and even contemplated relocation to adapt to a changing climate. The changes brought about by sea ice loss could also change economic opportunities in Arctic communities, as large swaths of previously inaccessible ocean become available for oil and gas operations, as well as commercial fishing. Melting ice may expose the Northwest Passage to cargo shipping, which would open up new trading opportunities for ports that were once inaccessible due to year-round sea ice.
In the Arctic, the ecological and economic effects of sea ice loss are occurring at a dynamic and rapid pace. It will take continued leadership by Arctic communities, scientists, policymakers, and other stakeholders to anticipate the effects of climate change on this fragile environment and work to sustainably manage it for future generations.
Published in March, 2017, by the Joint Ocean Commission Initiative.