Chuck Bednar for redOrbit.com – @BednarChuck
During a drastic shift in climate known as “Snowball Earth,” even places close to the planet’s warmer equatorial regions would have experienced Arctic-like temperatures, according to new research published this week in the Proceedings of the National Academy of Sciences.
The study authors analyzed the oxygen isotopes of rocks that had been exposed to the meltwater of ancient glaciers. They found that a global deep-freeze occurred 2.4 billion years ago, and that the annual mean temperatures were roughly -40 degrees Fahrenheit.
Everything was frozen
The researchers examined the oxygen isotopic composition of Proterozoic rocks that had been hydrothermally altered by ancient meteoric waters, some of which originated from glaciers that existed on “Snowball Earth.” They explained that this analysis gave them new insight into the climate and the hydrology during this stage in the planet’s history.
According to Discovery News, the data they collected indicates that the planet’s oceans became frozen into a sheet of ice and glaciers that were 1,000 feet thick. Those conclusions contradict existing theories that claim that there were open patches of unfrozen water that existed in the equatorial regions during the first of at least two “Snowball Earth” events.
“These events are fascinating. We had times where we really had a completely frozen Earth. If you go now to tropical regions and you imagine thick glaciers and all the oceans frozen, it’s crazy I think, but it appears to be that this has happened,” Daniel Herwartz, a geoscientist with the University of Gottingen in Germany and one the authors, told the website.
We think that Elsa from Frozen would have flipped out.
What did the deep freeze mean for life on Earth?
Climatologists and other experts have been at odds about whether or not some of the planet’s oceans would have remained at least partially liquefied during this period, and previous studies have been reliant upon climate models, not actual data and observations. The new study changes that by searching for a third oxygen isotope in rocks that were once near the equator.
The researchers examined 700-million-year-old rocks from China and 2.4-billion-year-old rocks from northwestern Russia, which would have been close to the equator at the time. They learned that Chinese rocks were exposed to water temperatures close to modern-day southern Greenland, but that the older samples had been subjected to far colder conditions.
“This low temperature would actually require that the whole Earth was completely frozen in and that we really had most of the oceans under hundreds-of-meter-thick ice,” Herwartz told the website. He and his colleagues believe that their research should shed new light on how life on Earth was affected by this extreme cold – specifically, whether or not it was still able to exist via photosynthesis or if it was limited to areas such as those near hydrothermal vents.
“Life on Earth originated and spread in shallow, light-filled, ice-free environments. Organisms in these environments evolved over billions of years, so glaciations, as long as they may be, are temporary interruptions to our biosphere, which is powered largely by photosynthesis,” added MIT geobiologist Tanja Bosak.
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