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1 .This is Scientific American 60-Second Earth. I'm David Biello. Your minute begins now.
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2 .What starts an Ice Age?
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3 .Clues exist in the remains of coccolithophores, a type of marine algae with a shell.
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4 .A study finds that some seven million years ago, the algae had to adapt to low levels of carbon dioxide in the atmosphere.
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5 .They pulled CO2 from the surrounding seas for photosynthesis as well as bicarbonate, commonly known as baking soda.
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6 .The study is in the journal Nature.
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7 .At that same time, sea surface temperatures were dropping,
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8 .plants that were more efficient at using CO2 came to predominate on land and vast glaciers began to expand on the continents, an Ice Age was underway.
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9 .The low concentrations of greenhouse gases in the atmosphere were thus linked to the era's cool climate.
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10 .That situation is now reversed thanks mostly to fossil fuel burning.
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11 .And the change is happening at least 30,000 times faster this time.
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12 .In May, atmospheric concentrations of CO2 touched 400 parts-per-million for the first time in human existence.
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13 .When they touch 500 ppm, the algae might no longer need the bicarbonate trick.
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14 .Your minute is up, for Scientific American 60-Second Earth. I'm David Biello.
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