Water is a phenomenal molecule, and the International Polar Year offers an opportunity for us to revisit this element of life that we often take for granted, especially its crystalized and frozen state. Water is both remarkably simple (two parts hydrogen-- the first element in the universe, one part oxygen-- the eighth element) and amazingly complex; its behavior at the "triple-point," where it flickers between liquid, solid and gaseous phases, amazes even atomic physicists.
Unlike other molecules, water is more dense in its liquid than solid states, which allows ice to float. Therefore, lifeforms can survive, even thrive, beneath the ice.
Scientists studying global climate change and the impact of human activities on the climate and ecosystems pay particular attention to the "cryosphere," the frozen part of the hydrosphere, which includes ice caps, sea ice and glaciers. In addition to studying long-term and abrupt changes in the melting of ice caused by the increased greenhouse effect, scientists also closely examine seasonal changes in snow and ice processes.
For example, in Greenland, the edges of the ice sheet melt during the summer months. However, the hydrologic cycle is accelerated by global warming, so more snow falls on the top of the icesheet in the winter. In order to understand the balance between melting and increased precipitation, scientists need to carefully measure both.
As another example, sea ice reflects from 50% to 95% of the sun’s energy that reaches it, depending on the age of the ice and the snow cover on it. Open water only reflects about 8%. The removal of sea ice increases the amount of heat absorbed into the water and leads to further melting and more open water. Water is very effective at storing heat, so massive melting in one season can add enough heat to the system to prevent ice formation the next season.
Many of us take ice for granted in our everyday lives. Through refrigeration we have easy access to ice to cool or freeze our foods. Creating ice requires a significant amount of energy, however, usually in the form of electricity.
As a catalyst for helping examine the role of the polar regions in the Earth system and in reflecting on our own use of the frozen phase of water in our daily lives, ice is nice. It is a perfect medium through which to explore, through arts and sciences, the wonders of nature, and an ideal way to begin the inquiry of the International Polar Year.
For ideas of classroom activites involving snow and ice, please visit our educators links and resources.
