By: Basant Khalil

Picture a starved polar bear crawling on the ground for 50 miles seeking a seal to satiate his hunger. In fact, this scenario has occurred previously. A starving polar bear, discovered dead in Svalbard as “little more than skin and bones,” perished due to the decline of sea ice on which he can hunt seals. What if you knew that the main reason for the sea ice decline is climate change that we humans induced?! When a species is “vulnerable” to extinction, we often build a fence around its habitat or hire experts to protect the species from its predators. Then, we can sleep peacefully, thinking about saving the world. However, we can’t build a fence to protect sea ice from rising temperatures. As one of the largest land carnivores in the world, polar bears, recognized as a keystone species, serve as the apex of the ecosystem by keeping biological populations in balance. Due to sea ice decline, we risk losing those cute creatures and inducing further catastrophes on the world as sea ice is crucial for the whole globe. This post investigates the role of sea ice relative to the bears, the arctic food chain, and the world.

Why is sea ice critical for polar bears?

Sea ice serves as a platform from which bears can hunt seals and hide from storms. The key to their survival throughout their habitat’s extreme temperature lies in their ability to exploit marine animals’ fat to store it when food is scarce. Studies have shown that the bears can consume up to 20 percent of their body mass in one meal, which, for an extremely heavy bear, is a lot of energy that it can use. Since only pregnant female bears enter the dens to overwinter, reduced caloric intake caused by lower availability of seals during the spring and summer months will compromise successful reproduction. They can, however, fast over eight months to stay healthy in the dens where there is no food, feeding their cubs milk containing up to 50% fat. Thus, the bears’ reproductive and survival success relies on the existence of sea ice habitat. One might conclude that if the ice melts faster and earlier than usual, the bears are prompted to fast sooner than expected, leading the cubs to be underfed and, possibly, dead. Sea ice is essential for a bear to hunt seals as, during fall, seals create and maintain breathing holes using the sharp claws on their fore flippers. As polar bears walk across the ice, they use their heightened senses to locate a seal’s breathing hole.

“A Mom and Her Cubs” by U.S. Geological Survey

Sea ice serves as the connection between the animals in the polar regions. Sea ice provides an inclusive surface to ice algae in the upper layers of the sea, where they can absorb sunlight. The increase of light absorbed in the spring advances algal growth, attracting small creatures known as zooplankton that feed on the ice algae. Zooplankton forms a significant connection in the food web, transferring energy from primary producers to larger animals, such as fish like Arctic cod. Arctic cod feeds on zooplankton that exists along the underside of the ice. Seals are the following stage in the food web, consuming ice-dependent prey like Arctic cod. One expected consequence of the bears’ extinction is the growth of the seal population because more of them will live longer and reproduce more, leading their food source, often fish, to shrink. Sea ice decline can lead to a threatening disturbance in the polar region by altering the food web, resulting in many species extinction and, possibly, influencing other species worldwide as the arctic food web is considerably associated with the global food web.

“Polar Bears Across the Arctic Face Shorter Sea Ice Season” by NASA Goddard Photo and Video

Global effects of sea ice

Sea ice loss leads to wider regions of open water and thinner ice that is more vulnerable to melting faster and easier with higher temperatures, influencing all species that rely on sea ice habitat for survival, including the polar bears. The ice’s bright surface reflects a lot of sunlight toward the atmosphere and, significantly, back into space, enabling temperatures closer to the poles to remain cool compared to the equator. When warming temperatures gradually melt sea ice, fewer bright surfaces are available to reflect sunlight into the atmosphere. Consequently, more solar energy is absorbed into the surface, causing ocean temperatures to rise and starting a cycle of warming and melting. Indeed, even a minimal rise in temperature can lead to larger warming over time, making the polar regions the most sensitive to climate change on Earth. The bears’ survival rate considerably influences the entire ecosystem’s health, such that sea ice is critical to sustaining a balanced life without disruption of the global ecology.

We should preserve sea ice!

It remains critical that we limit climate change effects to preserve more sea ice. Sea ice loss, as indicated in the past paragraphs, will induce profoundly catastrophic consequences, including polar bear population decline, which will cause further seal population growth that can disrupt the food web. Through sea ice loss, we risk multiple species loss worldwide and ocean water overflowing, causing potential flooding due to the increase of sunlight absorbed into our ecosystem. By observing its role within polar bears’ bodies, the food web, and the universe, it is crucial that we conserve the ice to hinder other impending catastrophes.

Is there hope to save the bears?

Certainly, climate warming causing sea ice decline is mostly human-induced. If we started it, then we can stop it, but we need to act quickly together to save the bears and the world from the impending consequences!
“Just us cute little polar bears freezing our little buns off!” by being myself is licensed under CC BY-ND 2.0

Works Cited

  • Elvin, Sandra S. “The large marine ecosystem approach to assessment and management of polar bears during climate change.” Elsevier, 2014. file:///C:/Users/Mona/AppData/Local/Temp/Temp1_ScienceDirect_articles_17Nov2020_18-06-55.438.zip/The-large-marine-ecosystem-approach-to-assessment-and-man_2014_Environmental.pdf. Accessed 17 Nov, 2020.
  • Kovacs, Kit M. Lydersen, Christian. Overland, James E. Moore, Sue E. “Impacts of changing sea-ice conditions on Arctic marine mammals,” Senckenberg, 17 April 2010.
  • file:///C:/Users/Mona/Downloads/Kovacs2011_Article_ImpactsOfChangingSea-iceCondit.pdf. Accessed 17 Nov, 2020
  • Stroeve, Julienne C. Serreze, Mark C. Holland, Marika M. Kay, Jennifer E. Malanik, James. Barrett, Andrew P. “The Arctic’s rapidly shrinking sea ice cover: a research synthesis,” SpringerLink, 8 June 2011. https://link.springer.com/article/10.1007/s10584-011-0101-1. Accessed 20 Nov, 2020.