Our Polar Seas


Plunging Into Our Polar Seas

The Earth’s polar regions are perhaps our planet’s most unique ecosystems – the Arctic dominated by floating sea ice and the Antarctic by ice sheets on the continent. The vast, isolated expanses of snow and ice, and the life which inhabits it, have fascinated mankind for ages. Yet much of the Arctic and Antarctic remain unexplored as they are characterized by extremely cold temperatures, heavy glaciation, and extreme variations in daylight hours (24 hours of daylight in the summer and complete darkness in mid-winter). Fascination may have been the impetus for polar research beginning in the late 1800s, but scientists now know that the Arctic and Antarctic are amongst the most vulnerable ecosystems in the world and need to be studied extensively as they hold the keys to understanding the Earth’s climate.

As the North and South Poles are the two coldest climatic regions on Earth, they play a vital role in regulating climate – acting as our planet’s cooling system. The global climate is controlled through a process called thermohaline circulation. As sea ice forms at the poles, the remaining salty, dense water sinks and is replaced by warmer, fresher surface water. This water movement creates the deep-ocean currents that move cold and warm water around the globe.

Unfortunately, the polar regions are currently at-risk due to continually increasing levels of anthropogenic carbon dioxide in the atmosphere. Carbon dioxide raises the global temperature by trapping heat that would otherwise escape directly into space – and the poles are warming at much faster rates than anywhere else on the globe. In the Arctic, sea ice cover is declining, as is the ratio of thick and thin ice cover. The amount of multi-year ice present in the Arctic has declined each year since the 1980’s due to warming temperatures, leaving mostly newer, thinner ice on the surface. The two lowest years on record (2012, 2020) for sea ice extent in the Arctic occurred in the past decade, and it is likely that the Arctic may have ice-free summers by the end of the 21st century. Warming temperatures in the Arctic may release even more carbon dioxide and other greenhouse gases, such as methane, by melting frozen soil called permafrost that keeps organic carbon in dead plants from decaying and delays its release into the atmosphere. This thawing may result in a positive feedback loop, in which thawing causes faster warming, which in turn causing more thawing. In the Antarctic, coastal glaciers are in retreat, land-based ice is shrinking, and ice melt is increasing as the South Pole has faced extreme warming over the last three decades. The increase in carbon dioxide is doing more than just raising temperatures. More carbon dioxide in the ocean causes it to become more acidic, negatively affecting small, shelled creatures, like pteropods, which are an important food sources for fish and larger animals.

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Webinar Series

View the NOSB’s polar-themed Professional Development Webinar Series recordings to learn more about the Arctic ecosystem and the formation and importance of sea ice.

2021 Professional Development Webinars: Carolynn (Carrie) Harris

January 4, 2021|

The sea ice that covers the Arctic Ocean is a haven for marine life in an extreme environment characterized by low temperatures and extreme seasonality. The seasonal patterns of ice melt and ice formation, as well as the loss of sea ice due to anthropogenic climate warming, affect life at all levels of the food chain.

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