An illustration of the Snowball Earth with some open water about the equator and a newly proposed patch of ocean at mid-latitudes
Huyue Song

In the course of a period of intense cold millions of years ago, practically all of the Earth might have been covered in glaciers. Identified as the “Snowball Earth,” this time frame reduce off oceans from the sun’s light and produced circumstances far much less hospitable than these of the final Ice Age that ended some ten,000 years ago. But now, a new study published final week in the journal Nature Communications is altering the concept of how the planet looked for the duration of this frigid era.

Rather than getting practically completely blanketed in glaciers, the study posits that Earth might have had sections that have been wetter than previously believed. By analyzing prehistoric sediment, scientists recommend that open oceans have been present considerably north of the equator for the duration of the Snowball Earth, and some organisms could have survived inside them.

“The important discovering of this study is that open-water—ice-free—conditions existed in mid-latitude oceanic regions for the duration of the waning stage of the Marinoan Ice Age,” Huyue Song, initially author of the study and a geobiologist at China University of Geosciences, tells Reuters’ Will Dunham.

The Marinoan Ice Age, which spanned 635 to 654 million years ago, was one particular of two “snowball events” to take spot for the duration of the appropriately named Cryogenian Period. Had the ocean’s surface been globally frozen more than, it would have restricted oxygen and nutrients from reaching the depths and produced it challenging for some organisms to persist, per the paper.

But some scientists think that specific life types did survive: Fossils from this period indicate that tiny organisms such as algae, which will need sunlight and open water, lived each prior to and just after the Snowball Earth. “You have to envision some sort of refuge exactly where these algae can survive,” Shuhai Xiao, a co-author of the study and geobiologist at Virginia Tech, tells Science’s Adam Mann.

To discover how life may well have eked out an existence for the duration of such frozen circumstances, the researchers analyzed a prehistoric layer of black shale, a form of sediment wealthy in organic matter, that would have been beneath the ocean for the duration of the Marinoan Ice Age, according to the Agence France-Presse (AFP). The shale came from Shennongjia National Forest in south China.

In the Marinoan sediment, the group identified fossils of algae, as nicely as nitrogen compounds that recommend the waters have been oxygenated, writes Science. This shows that life could have existed underwater at the time, they say.

Some previous climate investigation had recommended that locations at low latitudes—just five to 15 degrees, or probably 20 to 30 degrees, away from the equator—were not frozen for components of the Snowball Earth period, per the paper. But the shale in the new study may well have resided in between 30 and 40 degrees north of the equator in the ocean, which means that open water could have existed at considerably larger latitudes than previously believed.

“Until now, ice-totally free places had been identified only in peri-equatorial regions,” Song tells the AFP. But “patchy, ice-totally free places might have existed considerably additional extensively.”

Nevertheless, Paul Hoffman, a Harvard University geologist who contributed to the Snowball Earth theory and did not participate in the new study, is much less convinced by the findings. He tells Science that he thinks it is additional most likely the fossilized algae lived in pools atop glaciers, alternatively of in open waters.

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