Why are some icebergs Green?

Decades-Long Mystery About Green Icebergs May Be Solved

Decades-Long Mystery About Green Icebergs May Be Solved

Antarctic explorers have spotted odd green icebergs for centuries and scientists now believe they have cracked the green-hued mystery.

Pure ice is blue because ice absorbs more red light than blue light.

A brand new study claims that the green color is the result of the iron oxides in the rock dust from Antarctica's mainland.

Iron is a key nutrient for phytoplankton, microscopic vegetation that kind the bottom of the marine meals internet. "But iron is scarce in many areas of the ocean", the researchers told Science News on Tuesday.

'It's like taking a package to the post office, ' Warren said in a statement.

In the 1980s, Stephen Warren, now a glaciologist at the University of Washington, took samples from blue and emerald icebergs and found that the green icebergs were made of marine ice.

Since we associate ice with the white colour, it seems obvious to think that icebergs are going to be all that way, of a pristine white.

"What is most unbelievable is not their color but rather their clarity, because they have no bubbles", said Warren to IFLScience. During an expedition, his team found that green ice contained the same amount of organic material as blue-meaning something else must be responsible for the emerald coloring. These bubbles cause the photons to change direction repeatedly by refraction and re-emerge to the surface, causing the effect of a whiter ice. He found that the clear jade coloration was due to marine ice, not glacier ice.

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Scientists from the United States and Australia may have finally solved the decades-long mystery surrounding green icebergs.

Researchers on top of a large composite iceberg in October 1996.

Icebergs that form from glacier ice that breaks off from the Antarctic ice sheet is partially made-up of frozen seawater collected at the glaciers' bases.

A partly-capsized iceberg embedded in sea ice. Dissolved organic carbon is yellow, so if pure ice is blue, the addition of yellow particles could turn the ice green, according to Warren.

They suspected an impurity in the ocean water underneath the Amery Ice Shelf was turning some marine ice green.

'Subsequent measurements of low DOC values in green icebergs, together with the recent finding of large concentrations of iron in marine ice from the Amery Ice Shelf, suggest that the color of green icebergs is caused more by iron‐oxide minerals than by DOC'.

He wondered if it was possible iron oxides are turning the common blue hue of ice a dark green.

In a new study published in the Journal of Geophysical Research: Oceans, researchers found marine ice varies in color due to the "abundance of foreign constituents in the seawater", particularly iron-oxide materials. His inspiration was born from research by oceanographer Laura Herraiz-Borreguero at the University of Tasmania, who found that the Amery Ice Shelf core had almost 500 times more iron than the glacial ice above. He explained that the minerals might have come from Antarctica's mainland when glaciers that flow over bedrock turned rocks into a fine powder and unloaded them into the ocean. This hunch will have to be confirmed by experiments that sample icebergs of different colors for their iron content and light-reflecting properties.

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