Climate Change: Winners and Losers
Lesson 3: Melting Polar Ice
Page 1 Page 2: Glaciers and Ice Caps Page 3 Review
Galciers and Ice Caps:
Both the North and South Poles are covered with ice in the form of glaciers and ice caps. Glaciers are on land, and ice caps cover the seas. As temperatures rise, more and more of this ice will melt.
You may remember from Lesson 1 that bond albedo--we will call this albedo for short--is the percent of the electromagnetic (EM) radiation from the Sun that is reflected away from Earth's surface back into space. EM radiation that is reflected away from us cannot get absorbed by the planet and does not warm us. As albedo increases, our planet gets cooler. You can test this with the Planet Temperature Calculator. At the Summary page, keep Earth values for Mass (1), Distance (1) and Greenhouse Effect (also 1; how hard is that?), and increase Albedo from 29 to about 35 or 40, then check the results. Temperatures drop. If you reduce albedo below current Earth levels--to 25, for example--temperatures increase.
To summarize:
Lower albedo - less energy is reflected; more energy is absorbed; temperatures rise.
Higher albedo - more energy is reflected; less energy is absorbed; temperatures drop.
Light colors reflect more EM radiation than dark colors. Ice is usually very light-colored, almost white. It reflects a lot of energy. It has a high albedo.
When ice caps and glaciers melt, the water or land beneath them gets exposed to sunlight. Both water and rock absorb more sunlight than ice. They have a low albedo.
As the ice in the polar regions melt, more EM radiation gets absorbed by the water or rock that was covered by it. Lower albedo leads to higher temperatures. This melts even more ice, which further reduces albedo. This is called a positive feedback loop: rising temperatures melt ice, which makes temperatures rise even more, which melts even more ice, and so on.
There is another problem caused by ice at the poles melting: it turns into water that eventually finds its way into the ocean. As more water enters the ocean, sea levels rise, shorelines move up onto higher land, and coastal areas begin to flood.
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