Unraveling the Mystery of the Snowball Earth

The Snowball Earth was when our planet experienced an extreme icehouse environment. The entire Earth, from the poles to the equator, was enveloped in ice, and temperatures plummeted drastically. However, the cause behind this drastic climate shift has long been debated and is a mystery among geologists.

A recent study by the University of Sydney, led by ARC Future Fellow Dr Adriana Dutkiewicz, offers a compelling answer to this climatic conundrum. According to the survey, the Snowball Earth phenomenon resulted from historically low volcanic carbon dioxide emissions. This was coupled with the weathering of a large pile of volcanic rocks, a process that absorbs atmospheric carbon dioxide.

"Historically low volcanic carbon dioxide emissions, aided by weathering of a large pile of volcanic rocks, were responsible for the Snowball Earth phenomenon" - Dr Adriana Dutkiewicz.

Unveiling the Mechanism of Snowball Earth

To arrive at this conclusion, the researchers at the University of Sydney applied plate tectonic modeling. They studied the evolution of continents and ocean basins following the breakup of the ancient supercontinent Rodinia.

Using advanced computer models, they were able to calculate the CO2 degassing of submarine volcanoes along mid-ocean ridges. The results revealed that the start of the Sturtian ice age, a part of the broader Snowball Earth phenomenon, precisely correlates with an all-time low in volcanic CO2 emissions. Furthermore, the CO2 outflux remained relatively low for the entire duration of the ice age.

Implications of the Study

Dr Dutkiewicz stated that there were no multicellular animals or land plants at the time of the Snowball Earth. The greenhouse gas concentration of the atmosphere was almost entirely dictated by CO2 outgassing from volcanoes and silicate rock weathering processes, which consume CO2. As a result, the atmospheric CO2 declined to a threshold that triggered glaciation, estimated to be below 200 parts per million, less than half of today's level.

This study not only presents a plausible explanation for the Snowball Earth phenomenon but also underscores the sensitivity of global climate to atmospheric carbon concentration. The findings provide a stark reminder of the delicate balance that sustains life on Earth and the potential implications of disrupting this balance.