Melting sea ice from above Copyright © Marlo Garnsworthy
I am in love with sea ice.
My first view of the ice came from a Hercules aircraft bound for McMurdo Station, Antarctica, in January this year, the first step in my voyage as Science Communicator for the SNOWBIRDS Transect research cruise aboard the RVIB Nathaniel B. Palmer.
But in preparing for my journey, I had been reading about sea ice for some time. Anxious about going to sea, I devoured as much information about the ship and the journey as I could to prepare myself. I soon came across this video by Cassandra Brooks.
I was hooked. While most of our voyage would be upon the wild Southern Ocean, well beyond the ice, I longed to experience sea ice as fully as I could.
Eager to know more about breaking ice, I came across this description of ice navigation (scroll right down) by Captain David “Duke” Snider. I don’t know how many times I listened to it and imagined crushing ice in the middle of the night, far from home and family, in such a remote and dangerous part of the world. Despite my trepidation, I couldn’t wait to go.
And I couldn’t get sea ice off my mind. The more I learned about this remarkable environment, the more I was enchanted.
You might imagine that the frozen seas are a barren and lifeless place, but nothing could be further from the truth.
Juvenile emperor penguin Copyright © Marlo Garnsworthy
Breaking ice in the Ross Sea, I saw Adélie and emperor penguins, Weddell and crabeater seals, skuas (a gull-like seabird), snow petrels, Antarctic petrels, orcas on the hunt, and more. But I knew so much more lay beneath the surface.
Sea ice is a vital habitat for the growth of phytoplankton, tiny plants (mainly algae and bacteria). Beneath the ice, zooplankton (tiny animals) drift, providing nutrition for krill and the larger animals that feed on them, such as fish, penguins, seals, and whales. During the eternal days of a polar summer, when the sun never sets, phytoplankton bloom in this nutrient- and light-rich environment, reproducing exponentially until the water can appear green and soupy.
The base of the marine food chain, phytoplankton not only feed our oceans but provide about the half the oxygen we breathe. They also act as a carbon sink, taking up massive amounts of carbon dioxide—a major greenhouse gas—from our atmosphere.
Crabeater seals resting on the sea ice, Ross Sea Copyright © Marlo Garnsworthy
Sea ice provides a safe resting place close to food for birds like penguins, mammals such as seals, and in the Arctic, walruses and polar bears. Some species also give birth on the sea ice.
The physics of sea ice are fascinating, too. Ice grows, shifts, flows with ocean currents, cracks, and melts, ever changing. In fact, sea ice has a direct impact on ocean currents because, as salty sea water freezes, brine is pushed out of the ice and trickles down through brine channels into the sea water below. The resulting extra-salty sea water is heavy and sinks, causing currents that drive ocean circulation worldwide.
Weddell seals rest beside a lead (open crack) in the ice. Copyright © Marlo Garnsworthy
Sea ice has high albedo, meaning it has a bright surface, reflecting around 80% of the sunlight that strikes it. Sea ice is vital in helping keep our planet cool enough for habitation and regulating our climate.
Penguin watching requires sunglasses due to the high albedo of sea ice. Copyright © Marlo Garnsworthy
I will be exploring in more depth the physics, ecology, and importance of sea ice in posts to come.
Yes, I am passionately in love with sea ice, and it’s my greatest dream to return to the ice, accompanying scientists aboard an ice cruise. I hope readers will come to love it, too, and help me fight for it. Our vital sea ice is melting, and without it, our world will be a very different place.
Adélie penguins and skuas at dawn, Ross Sea Copyright © Marlo Garnsworthy