This Week in Ice: Nov. 12–18

This week, NASA’s Operation Icebridge offered us more spectacular views of Antarctica. Operation Icebridge uses research aircraft to capture images of Earth’s polar ice “to better understand connections between polar regions and the global climate system. IceBridge studies annual changes in thickness of sea ice, glaciers and ice sheets.”

This is one of my favorites:

 

Sea Ice

Sea ice extent and concentration in both the Arctic and Antarctic remain well below average. You can read a full summary of October’s Arctic and Antarctic sea ice conditions here.

ARCTIC

Arctic sea ice grows rapidly at this time of year. October’s Arctic sea ice concentration was the fifth lowest on record for that month (satellite data from 1979 to present).

Current conditions: 

ac

Credit: NSIDC

arctic

Credit: NSIDC

Unlike Antarctic sea ice, which is usually only one to two years old due to seasonal melting, Arctic sea ice can last for multiple years. This animation shows how older Arctic sea ice is now thinning and melting.

 

ANTARCTIC

As days lengthen and temperatures increase in Antarctica, with the approach of the Austral summer, sea ice melts. October was tied with 2002 for the latest maximum sea ice extent and the second lowest Antarctic maximum extent (satellite data, 1979 to present).

Current conditions:

antc

Credit: NSIDC

ant

Credit: NSIDC

This one by Zach Labe shows more data:

Wind has a large role in sea ice formation, comparable to or even more important than temperature and rain says researcher Massimo Frezzotti. This research explores the processes that have affected sea ice variability, as well as the abundance of seals and penguins in the Ross Sea, over the last ten thousand years.

twitterkrill

Antarctic krill under ice                                                Copyright © Marlo Garnsworthy

Krill are small shrimp-like crustaceans and a vital link in marine food chains. Antarctic krill, depicted in my painting, feed sea birds, penguins, seals, and whales.

A study in the Weddell Sea has shown that sea ice is a critical habitat for krill larvae during winter, and they find refuge from predators under the ice. But while it may be safer, it is not a food-rich environment. Krill do graze under the ice during the day, then at night drift down and away to more favorable feeding zones.

Glaciers & Ice Shelves

This graphic shows how land ice has decreased in Antarctica and Greenland from 2002 until the present.

One of the numerous reasons we should care about ice loss is that melting ice sheets not only raise sea levels but will have an effect on tides the world over. New research shows that, as ice sheets melt, sea levels don’t rise evenly across the world, and it matters which glaciers melt. In some places tide ranges will be increased, and in others reduced, thereby impacting coastal communities. These changes could also have an effect on larger scale ocean currents. Ocean currents affect our global climate, among other things. (Sea ice also has an effect on ocean currents, a subject I’ll be exploring in weeks to come.)

NASA has provided a new tool to show how sea level rise may affect 293 coastal cities around the world.

The Pine Island Glacier, which flows into West Antarctica’s Amundsen Sea, makes the biggest contribution to sea level rise. This is the same glacier that carved a massive iceberg, four times the size of Manhattan back in September (and a mere month later, it broke into pieces too small to track). Here, warmer waters interact with floating ice, weakening the ice shelf from below.

Watch an Alaskan glacier retreat over time:

 

Icebergs

Thanks to Operation Icebridge, we have our first closeup views of massive iceberg A-68A, previously only seen via satellite imagery.

iceberg

Credit: NASA/Nathan Kurtz

Scientist Stef Lhermitte notes further cracks in the Larsen C ice shelf, from which A-68 (the initial even larger iceberg) calved back in July.

DSC_0515

Copyright © Marlo Garnsworthy

In the absence of any other significant iceberg news, I offer this picture of a wind-and-sea-tossed  iceberg I took during a gale in Antarctica’s Ross Sea. Note the blue ice to its left. Blue ice looks that way because, over thousands of years, it has become very compressed, pushing out the air bubbles that give ice and snow its white appearance. Blue icebergs consist of very old ice, which has calved from glaciers and ice shelves into the sea.

And to finish, I hope you’ll enjoy this excellent series of short videos, showing how satellites have been monitoring life on Earth for over 20 years.

 

As always, I am not a scientist, just a writer/illustrator and science communicator passionately in love with sea ice. I welcome input and corrections by polar scientists as I learn more about this remarkable and vital part of our planet and bring this knowledge to a wider audience. 

 

 

 

One thought on “This Week in Ice: Nov. 12–18

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