The science behind the color of an iceberg

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What comes to mind when thinking about an iceberg is usually a large chunk of white ice floating in the sea. Icebergs are typically chunks of ice that separated from a glacier or ice shelf. The most common icebergs are white because it has been covered with snow.

Black and white iceberg on the South Georgia Island. /VCG Photo

However, many people are surprised to find that icebergs can form in many different colors other than white. According to basic physic, an iceberg that is formed by ice without contaminants should be blue. Because blue light is harder to be absorbed by the “pure ice” than the yellow or red lights. Therefore blue is the “true color” of a "pure" iceberg.

Blue iceberg is formed by "pure ice". /VCG Photo

Vibrant blue iceberg. /VCG Photo

When icebergs are formed with frozen seawater, which contains rich algae and minerals, they will display different colors. Dead organic matter from sea life and iron-rich minerals both give the icebergs shades of green and yellow. Large amounts of dead organic matter reflect yellow light, but a small amount will make an iceberg shimmer like jade.

Green iceberg shimmers like jade. /VCG Photo

A green iceberg. /VCG Photo

Breaks in the ice allow fresh saltwater to come in and then it freezes. The occasion causes the ice to turn another color.

The stripes are caused by cracks on the iceberg. /VCG Photo

Beautifully striped icebergs. /VCG Photo

A small striped iceberg. /VCG Photo

Blue stripes on white iceberg. /VCG Photo

Black stripes are caused by sediments on the ice. /VCG Photo

Yellow, green and multicolored icebergs only exist in Antarctica because they require the existence of glacial ice shelves and extremely cold conditions to freeze seawater. Icebergs in the Arctic are white or blue if their snow jackets melt away. However, a warming ocean could reduce the number of tinted icebergs, which are already rare.