[Rockhounds] What turned Earth into a giant snowball 700 million years ago?

[Kreigh Tomaszewski]

Australian geologists have used plate tectonic modeling to determine what
most likely caused an extreme ice-age climate in Earth's history, more than
700 million years ago.

The study, published in *Geology*
<https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51669.1/633748/Duration-of-Sturtian-Snowball-Earth-glaciation>,
helps our understanding of the functioning of the Earth's built-in
thermostat that prevents the Earth from getting stuck in overheating mode.
It also shows how sensitive global climate is to atmospheric carbon
concentration.

"Imagine the Earth almost completely frozen over," said the study's lead
author, ARC Future Fellow Dr. Adriana Dutkiewicz. "That's just what
happened about 700 million years ago; the planet was blanketed in ice from
poles to equator and temperatures plunged. However, just what caused this
has been an open question.

"We now think we have cracked the mystery: historically low volcanic carbon
dioxide emissions, aided by weathering of a large pile of volcanic rocks in
what is now Canada; a process that absorbs atmospheric carbon dioxide."

The project was inspired by the glacial debris left by the ancient
glaciation from this period that can be spectacularly observed in the
Flinders Ranges in South Australia.

A recent geological field trip to the Ranges, led by co-author Professor
Alan Collins from the University of Adelaide, prompted the team to use the
University of Sydney EarthByte <https://www.earthbyte.org/> computer models
to investigate the cause and the exceptionally long duration of this ice
age.

https://phys.org/news/2024-02-earth-giant-snowball-million-years.html