Arctic Ice (JSEP pt.3)

July 16, 2022

Written by: Caroline Kim

In part 3 of this JSEP series, we’ll be discussing one of the arctic’s most distinguishing characteristics: ice-ocean systems. This tangible network of forces involve not only ice and oceans, but also energy from the sun, winds, snow masses, and more. One major driving force to note is the different fluxes in the system (snowfall, radiation, momentum, precipitation, etc.). When discussing ice-ocean systems on the arctic, it’s key to differentiate between land ice and sea ice. Essentially sea ice is formed from freezing ocean water (therefore the melting of it won’t cause any displacement), whereas glacier ice is formed on land (the melting of it would cause displacement). Sea level rise can be caused by many factors, some of which include thermal expansion, acceleration of melting ice sheets, and isostasy (vertical land motion); isostasy is the idea that when an ice sheet melts off the land into the water, the pressure on that land is relieved, so it rises, causing sea levels to drop locally but rise elsewhere. Some ways in which ice breaks apart faster include low basal drag and buttressing forces: forces that oppose each other such as glacial shift/ocean currents can cause glacial undercut and cause ice shelves to break apart.

In an experiment we conducted, we froze water with sediment mixed in, and let it sit out afterwards to observe the melting behavior. Some things noted were that rougher surfaces caused more friction and heat, resulting in a higher rate of melting of the ice. Additionally, finer particles such as sand melted faster and ran out of the ice than larger items such as pebbles. In a second experiment that was conducted, a cup of pure ice was frozen as well as a cup of ice containing black carbon (burned paper). Within this experiment, the melting rates and albedo (the reflectivity of a surface) were measured and compared. We determined that the lower the albedo (less reflectivity), the more energy/heat that is absorbed, and therefore the faster it melts. Since darker colors absorb more light, the ice with black carbon mixed in melted at a faster rate, and also had a cycle of positive feedback. In other words, the more it melted, the more heat it received (the black carbon settles at the bottom and as you get closer, the darker the color of ice) and the faster it melted. Fundamentally, the rate of melting in pure ice was constant while the rate of melting in the black carbon infused ice increased over time.

In an effort to help prevent/protect against this, some proposed solutions include space mirrors, increased reflectivity from aerosols/oceans, increasing reflectivity in low clouds by spraying sea salt on them, and reflective glass powder, which would increase the ice surface’ albedo and slow down the melting rate. Other more behavioral solutions include taking public transit, placing taxes on carbon, reducing the amount of solar radiation that reaches the cryosphere (frozen parts of the planet), and the blocking of the entry of warm water. As more testing and research in this area is needed to work toward a more promising solution, the next and final part of this series will include more research from my JSEP group!

Sources:

Joint Science Education Project (Graduate students/Educators)

Brita Horlings

Ayobami Ogunmolasuyi

Ian Raphael

Joel Wilner