For the theme of ice, I am going to talk about ice itself and how it occurs in nature. Ice is one of the phases of water, almost one tenth of our planet is covered with it. Two large sheets of ice are covering almost the entire Antarctic and Greenland, this amounts to approximately 15 million square kilometers, of the Earth’s total immersed land(1). To put this into prospective, the Antarctic ice sheet alone spans about 13.5 million square kilometers (area of United States and Mexico combined).

Ice is quite easy to make and depending on the impurities and amount of air bubbles, it appears opaque (white) or transparent. Based on the molecular arrangement ice can exhibit 16 different packaging geometries. The variations depend on the temperature and pressure. The most commonly seen ice has a hexagonal crystalline structure, denoted Hexagonal ice (ice Ih).

I would recommend the following link if you would like a more detailed explanation on Ice structures and this link for 3D molecular shapes of Ice and water.

Figure:1: Snowflakes by Wilson Bentley, 1902. Snow is ice that grows from water vapor in Earth’s atmosphere, which is why it usually displays crystal shapes.

The Antarctic has many layers deposited over hundreds of years. Similar to the theory from the movie Jurassic park, where the blood of a dinosaur was recovered from a preserved mosquito. Airborne relics of Earth’s earlier climate including dust, air bubbles, sea salts, volcanic ash, and soot from forest fires are preserved in glacial ice(2). These relics give scientists a glimpse to our planet’s climate and atmosphere and also the changes over thousands of years.

Scientist have taken inspiration from ice is forming techniques, to design new materials. Glacial ice and other bio-materials are formed layer by layer, under specific (natural) conditions. Knowing which parameters play an important role in the materials properties is the key. These parameters can then be implemented into artificial bio-inspired synthetic materials, using innovative techniques such as layer-by-layer assembly or ice-templated crystallization (3).

Figure:2(a) & (b) Ice cores harvested from Greenland. (c) Circular disk from the ice core shows presence of stored gasses in form of bubbles.

How do natural organisms deal with ice ?

Coming to strategies that we use to cope with ice, many inventions have been made for locomotion on ice. We employ chains, special materials for tires and skis or snow shoes for walking on ice. So how do other natural beings cope with ice? Some animals like seals, penguins and bears, have developed physiological adaptation. Seals and penguins spend time on both ice and water and they often are seen sliding, turning and braking on ice. While getting back on ice from water seals and penguins use their feathers and fur for grip on ice. This enables them climb up to 60° inclinations. “Numerous other animals that live in the snow have bristles on their running or creeping surfaces, for the same mechanical reasons.“(4)

Polar bear paws are perfect for roaming on the ice. Paws measure up to 31 centimeters and enable them to distribute weight while walking on thin ice. Black foot pads on the bottom of each paw are covered by small, soft bumps known as papillae. Papillae grip the ice, keeping the bears from slipping and provide protection against sharp ice edges (5). Polar bears also can also reduce their metabolism when food is running low, this enables them to go without food for longer period.

Figure:3

In the regions where the temperatures drop much below 0°C snow serves as an excellent insulation medium. Many animals use snows insulation properties and dig snow caves in which to hibernate through the winter. New snow (uncompacted snow) has a up to 90% air, this reduces the air movement and heat transfer is reduced. The ground has a relatively higher temperature due to the heat accumulated over the summer, snows down the flow of heat from the warm ground to the cold air above.

Snow and insulation:

Figure:4: Man made ice constructions.

Snow campers also dig snow caves to sleep in extreme conditions, comparatively the air temperature inside a snow cave will remain higher than the outside air temperature, which can drop significantly at night. Hence it is recommended to leave half a meter on the top as the deeper snow pack is warmer because it is close to the warm ground. Ice is also used as in construction material, the ice buildings though are labor intensive, the construction material is free. Mostly the hotels melt in summer and are build from scratch every year.

To conclude, the structure of ice is unique itself and the way natural organisms have developed adaptions/strategies to deal with ice, provides us with a huge source of inspiration. If some of you happen to know about other strategies nature uses with respect to ice, please do share with us 🙂

References:

1. http://www.eniscuola.net/en/argomento/cryosphere/the-earths-ice/how-much-ice-is-there-on-the-earth/
2. gov. (2016).Climate at the Core: how scientists study ice cores to reveal Earth’s climate history | NOAA Climate.gov. [online] Available at: https://www.climate.gov/news-features/climate-tech/climate-core-how-scientists-study-ice-cores-reveal-earth%E2%80%99s-climate [Accessed 2 Nov. 2016].
3. Barthelat, Francois. „Biomimetics for next generation materials.“ Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 1861 (2007): 2907-2919.
4. Tributsch, Helmut. „How life learned to live: Adaptation in nature.“MIT PRESS, CAMBRIDGE, MA(USA). 1982. (1982).
5. Paws, Claws, Ears and Tails | Polar Bears International. (2016).org. Retrieved 2 November 2016, from http://www.polarbearsinternational.org/about-polar-bears/essentials/paws-claws-ears-and-tails

Figures:

1. By Wilson Bentley – Plate XIX of „Studies among the Snow Crystals … “ by Wilson Bentley, „The Snowflake Man.“ From Annual Summary of the „Monthly Weather Review“ for 1902., Public Domain, https://commons.wikimedia.org/w/index.php?curid=22130
2. (a)Ice pics -Summitvoice.files.wordpress.com. (2016). [online] Available at: https://summitvoice.files.wordpress.com/2011/03/ice-core-striations.jpg [Accessed 2 Nov. 2016].
   (b)Heritage, N. (2016). Ice samples from Greenland and Russia provide clues to past and future climate change. [online] The Archaeology News Network. Available at: https://archaeologynewsnetwork.blogspot.co.at/2015/09/ice-sample-from-greenland-and-russia.html#8uEh3YU54uVLfFS9.97 [Accessed 2 Nov. 2016]. (c) Howweseetheenvironment.files.wordpress.com. (2016). [online] Available at: https://howweseetheenvironment.files.wordpress.com/2015/05/ice-slice.jpg [Accessed 2 Nov. 2016].

3.  (a) Upload.wikimedia.org. Retrieved 3 November 2016, from https://upload.wikimedia.org/wikipedia/commons/5/59/Polar_Bear_floating.jpg Commons.wikimedia.org. (2011).
   (b)Crabeater Seals in Pléneau Bay, Antarctica (6058639203).jpg – Wikimedia Commons. [online] Available at: https://commons.wikimedia.org/wiki/File:Crabeater_Seals_in_Pl%C3%A9neau_Bay,_Antarctica_(6058639203).jpg [Accessed 3 Nov. 2016].

4. (a) 2016): Nsidc.org. Abgerufen am 03. 11. 2016 von https://nsidc.org/sites/nsidc.org/files/images//snowcave.jpg.
   (b) Untravelledpaths – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17362446
   (c)  Art of Backpacking – Flickr: SnowCastle, Kemi, Finland, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=27872101