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 Technology.org.
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.
via Tallbloke’s Talkshop
January 6, 2020 at 01:30PM
Iowa Climate Science Education 