This sea ice in the Beaufort Sea is light in color compared with the dark ocean water. The sea ice reflects most of the sunlight that hits it. The ocean water absorbs most of the sunlight that hits it.
Ice-Albedo Feedback: How Melting Ice Causes More Ice to Melt
All winter long in the chilly Arctic, sea ice grows larger as the ocean water freezes. A blanket of fresh white snow covers it. The white snow reflects the sunshine that hits it.
As summer begins, the weather gets a little warmer. Warmer temperatures melt the blanket of snow that was on top of the sea ice. There are pools of water from the melting snow on top of the ice. The ice breaks into giant pieces like a puzzle. The ice is darker in color than the snow. The pools and cracks are also darker. And where the ice has melted, there is dark ocean water instead of ice. All these changes make the surface darker so more of the sunshine is absorbed, and less is reflected. Holding onto the heat from the sunshine causes more ice to melt. This causes more sunshine to be absorbed and more warming.
This happens every year as the seasons change. It is a normal process. However, it is changing as Earth’s climate gets warmer.
Earth is getting warmer as more greenhouse gases are released into the atmosphere. This makes the snow on top of the ice melt earlier in the spring. Temperatures drop to the chilly levels needed for sea ice to freeze a little later each autumn. There is more time during the summer for the ice to melt and less time in the winter for ice to form again.
This process of a little warming causing more warming is called the ice-albedo feedback. The ice-albedo feedback can turn a small climate change into a big climate change. The sea ice is melting fast in the Arctic Ocean. Scientists have discovered that there may be no more summer sea ice within the next few decades.
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The Summer 2010 issue of The Earth Scientist
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, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
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