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This is Scientific American 60-Second Earth. I'm David Biello. Your minute begins now.

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Imagine paradise.

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Now imagine the Bahamas.

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Hard to tell the difference.

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The island nation boasts brilliant white sands, clear waters and vibrant coral reefs.

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The waters of the Bahamas are so clear because they're low in nutrients.

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They're therefore relatively free of the microscopic life that turns richer waters murky,

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and is normally associated with the deposition of calcium carbonate.

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So how did those reefs come to be?

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A group of scientists argue that dust from across the Atlantic in Africa may have initiated the process.

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Dust blows off the Sahara today, reaching all the way to the Americas.

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Fertilized by the dust, cyanobacteria can then grow and pull carbon dioxide out of the water.

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That activity in turn causes calcium carbonate to precipitate, an event known as a whiting.

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And the cyanobacteria also fix nitrogen from the atmosphere, helping other microorganisms to thrive.

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This may have been going on for a very long time.

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Enough of such cyanobacterial work over enough time and eventually you get the Bahamas, built out of calcium carbonate.

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At least that's what's suggested by trace elements in Bahama sediments.

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The hypothesis is in the journal Geology.

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Fertilizing similarly nutrient poor waters might help reduce rising levels of carbon dioxide that are causing uncomfortable global warming.

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And maybe we'd get some pretty nice islands out of the deal eventually.

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For Scientific American 60-Second Earth. I'm David Biello.

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