How did life survive in the Snowball Earth? Scientists might have cracked the mystery

Posted: January 6, 2020 by oldbrew in climate, History, Ice ages, Ocean dynamics, research

The researchers do admit that ‘Snowball Earth is just a hypothesis’, but that period seems to have been an era of the most extreme long-term cold spell(s) ever detected on Earth.

There is very little life in Arctic tundras and glaciers. However that was the situation in a big portion of the world during Ice Ages, says

How did life survive these difficult periods? How didn’t everything just die, being cut off from any kind of sources of nutrition and oxygen?

Scientists examined the chemistry of the iron formations in Australia, Namibia, and California to get a window into the environmental conditions during the ice age. They selected rocks left there by the ice age, because they are representative of the conditions during that difficult period for life.

By analysing these rocks scientists from the McGill University were able to estimate the amount of oxygen in the oceans around 700 million years ago.

Oxygen concentration is a crucial condition for sustainability of life. Without oxygen everything dies in a massive domino chain. And scientists did find that a huge portion of the ocean was uninhabitable due to a low concentration of oxygen, but some areas, particularly where the grounded ice sheet begins to float there, became a critical source of oxygenated meltwater.

This effect, called the glacial oxygen pump, enriches water with oxygen. Air bubbles trapped in the glacial ice are released into the water as it melts, becoming a crucial supply of oxygen for various life forms, including eukaryotes.

Scientists believe that this explanation answers a question that has been puzzling them for decades – how did life on Earth survive the Snowball Earth time 700 million years ago, when our planet fell into the most severe ice age in its history?

Professor Galen Halverson, one of the authors of the paper, commented: “This study actually solves two mysteries about the Snowball Earth at once. It not only provides an explanation for how early animals may have survived global glaciation, but also eloquently explains the return of iron deposits in the geological record after an absence of over a billion years”.

Full article here.
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Original McGill University press release here.

  1. Jim says:

    Interesting, but a wrong premises again. This is a ” life as we know it” , not a ” life” article. Looking into Earth extremephile life. There may be other ways that life was created. After all, life finds a way to survive. Which implies, it started from some other source, something added a catalyst, to a situation. That was not natural to that environment.

  2. gbaikie says:

    700 million years ago, the moon was significantly closer to Earth and Earth rotated faster and it was 200 million years before plants and animals were living on the land areas. And it would 500 million years before any ocean floor would continue to exist into modern times.
    700 million year age there was not much oxygen in the atmosphere and there was a lot more CO2 and the atmosphere.

    There probably was about same amount of atmospheric mass, same amount ocean water and same amount of continental land mass. Or somewhere around 70% ocean area and 30% land area, though even in the last million years there is some variation due to rising and falling sea levels and one could expect and even more variation is possible in tens and hundreds of millions of years. But it does not seem possible to say there more land area or less land area 700 million years ago and 30% of land is probably a better guess than 20 or 40% land area.
    Likewise there may have been more or less water on Earth, and the ocean might been more or less salty and Earth could have more or less atmospheric mass.

    Most would agree that sun was dimmer. But it seems to me the sun might been more variable {and more dangerous}. And Earth probably had less Ozone. And both of these would made living on land more hostile.
    Also our present orbit varies over tens to hundred thousands of years, as does the tilt of rotation and Magnetic fields, flip. These elements could quite different 700 million years ago.
    But it seems a good guess is that Earth had more volcanic activity 700 million years age as compared to volcanic activity on Earth as compared in the last 100 million years.

    Currently most of Earth volcanic activity occurs under the ocean, and 700 million years ago, one could assume most of it’s volcanic activity occurs under the ocean- and there is more of it.

    Our present ocean floor is both hot and cold. Ocean water is coldest near ocean floor- cold dense salty water is the most dense. And thick ocean mud can be warm and you have volcanic hot spots.
    And you have pools lethal/toxic stuff on ocean floors. And any and all {or more} of this stuff could be happening on the ocean floor 700 million years ago.
    But if you examine an “average” part of surface of ocean floor, it’s roughly cold, because it’s mostly cold water at floor of the ocean, Though you aren’t find say – 40 C or colder.

    At at one time people thought bottom of our ocean was barren of life, today we know there is lots of life at bottom of ocean and this life is supported by black smokers or volcanic heat. And one could say 700 million years ago, the same thing was happening.

    I don’t think there was ever a snowball earth, but there could been a time when large part of land area was covered by ice. But land is small part of Earth, and that life [microbial} had hard time living on land 700 million ago, has nothing to do with a Snowball Earth.

  3. oldbrew says:

    BBC: Torridon rocks show signs of previously unknown ice age

    ‘Evidence of a previously unknown ice age that occurred millions of years ago has been discovered in the north west Highlands, scientists say.

    University of Aberdeen geologists have found features in rocks in Torridon caused by pebbles falling from melting icebergs to the bottom of lakes.

    The rocks date to a “relatively calm” period in the Earth’s evolution dubbed the “boring billion”.

    The geologists said it was the first evidence of glaciation at this time.

    The boring billion took place from 1,800 to 800 million years ago.
    . . .
    The glaciation came at a time when Scotland was located at the same latitude as South Africa.’