Brilliant green pools teeming with life have been found among remote Antarctic sea ice. The pools owe their colour to the high amounts of algae in the water. The pools were observed in the Amundsen Sea’s polynya, a region of seasonally open water surrounded by sea ice.
Polynyas are nutrient-rich havens for animals big and small. They are often hundreds of miles wide and can occur for two reasons: because warm air or water melts sections of ice away or because wind blows masses of ice away from the coast.
Ice contains micronutrients that are vital for plant growth. When summer sea ice melts it can release these nutrients into the water, creating algae blooms. The influx of micronutrients is further enlarged due to the melting of Antarctican glaciers and sea as a result of global warming.
As a result of this massive influx of nutrients water in the polynya has literally been turned green by chlorophyll, the pigment algae use for their photosynthesis. It is in fact five times greener than parts of the region where the Amazon empties into the Atlantic.
But unlike the negative effects algae blooms often have on life in lakes and ponds, the polynya is not only teeming with life, it is also taking up carbon dioxide from the atmosphere at an exceptional rate. Measurements showed only 100 parts of carbon dioxide over the polynya, compared to the average 390 parts per million in the Earth’s atmosphere.
But this global warming boon is most likely only temporary, as polonyas will disappear along with the sea ice if the world continues to warm. So global warming may be the cause of the extremely green polynyas, but it may also be the end of it. At least it is an important step in unraveling the effect of climate change on the ocean.
© Jorn van Dooren | www.bitsofscience.org