Name: How Life Survived When Earth Was Covered in Ice
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Seven-hundred-million years ago, ice threatened to make our planet uninhabitable, snuffing out new complex life forms. From this climate catastrophe, new forms of life arose, eventually leading to the living world today. But it was a close call.

Hundreds of millions of years ago, Earth was encased in ice. How did life survive?

How Life Survived When Earth Was Covered in Ice

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Seven-hundred-million years ago, ice threatened to make our planet uninhabitable, snuffing out new complex life forms. From this climate catastrophe, new forms of life arose, eventually leading to the living world today. But it was a close call.

Hundreds of millions of years ago, Earth was encased in ice. How did life survive? Scientists study how life survives in ice extreme cold today to find out.

Hundreds of millions of years ago, Earth was encased in ice. How did life survive? Scientists study how life survives in extreme cold today to find out.

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Speaker 1We know that life must have survived through Snowball Earth because we still have a lot of life in the Earth today. We had life before and after, so somehow it must have survived.NarratorBut it's hard to prove where, as all the ice from back then is melted.Speaker 1To understand how life survived in ice in the past, then we look to how life survives in ice today. And there is one habitat that Snowball Earth scientists are particularly interested in. So we're going to see if we can try and find that today.NarratorThere's more to this frigid landscape than meets the eye.Speaker 1What I found here is a hole in the glacier surface. We refer to this as a cryoconite hole. Sediment lands on the glacier surface, swept in by water and by wind. Then the radiation from the Sun warms it, and it melts the underlying ice. So it melts almost vertically down to make this pocket that we see here with meltwater at the bottom and open at the top.NarratorLook hard enough, in the right places, and you'll find these on glacial surfaces everywhere.Speaker 1The cryoconite holes are perfect for microorganisms because they have access to the Sun and they have access to meltwater.NarratorThat makes these holes refuges for a variety of life.Speaker 1We're going to try and sample this cryoconite hole. I'm seeing some bits are a little bit green, so they might be bits of photosynthetic microorganisms or they might be bits of plants.NarratorOther samples have revealed even more life.Speaker 1A huge range of organisms from fungi to micro animals. This captures the diversity of the organisms living in cryoconite holes, not just in species, but in size and shape and function.It's surprising and it's quite magnificent that these quite empty looking spots can have this much diversity.NarratorEven when life like this is subjected to harsh Snowball Earth conditions, it survives.Speaker 1For us as humans Snowball Earth will always seem like a harsh, almost impossible planet to live on. However, when we look at the depths of Antarctica, and the middle of ice sheets in the Arctic, there is life wherever you look for it.

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How Life Survived When Earth Was Covered in Ice

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