Over 700 million years ago, Earth was a frozen wasteland. Ice stretched from pole to equator, and temperatures plummeted so low that entire oceans may have been covered in thick ice sheets.
This extreme period, known as the Sturtian glaciation, remains one of the most baffling climate events in Earth’s history.
How did our planet get trapped in such an enduring deep freeze?
For decades, scientists have debated the cause of this prolonged ice age, but new research has finally uncovered the answer—a drastic drop in volcanic carbon dioxide (CO2) emissions.
The study, published in the journal Geology, reveals that tectonic shifts and reduced volcanic activity triggered the Sturtian glaciation and kept Earth frozen for an astonishing 57 million years.
How Volcanic CO2 (Or Lack of It) Froze the Earth
Volcanic eruptions are usually associated with warming the planet, but this time, the opposite happened.
According to a research team in Australia, led by Dr. Adriana Dutkiewicz, CO2 emissions from mid-ocean ridges reached a historic low around 717 million years ago.
This greenhouse gas plays a vital role in trapping heat, and when volcanic activity slowed, less CO2 was released into the atmosphere.
The result? Earth lost one of its primary heat-trapping mechanisms, triggering a catastrophic cooling event.
Dr. Dutkiewicz explains:
“Imagine Earth almost entirely frozen, locked in ice from pole to equator. That’s exactly what happened, but the reason behind it was a mystery—until now.”
The Unexpected Role of a Supercontinent
There’s another twist to the story.
Around this time, the supercontinent Rodinia was breaking apart, exposing vast areas of fresh rock to the atmosphere.
This triggered a process known as silicate weathering, which absorbs CO2 and locks it into minerals.
The Franklin large igneous province (LIP), a massive volcanic region in what is now Canada, underwent rapid weathering, removing even more CO2 from the air.
For years, scientists suspected that volcanic eruptions contributed to cooling by releasing sulfur aerosols that reflect sunlight.
While this may have played a role, the new study suggests that the real culprit was the long-term reduction in CO2 emissions, which kept temperatures too low for millions of years.
How Earth Stayed Frozen for 57 Million Years
Most ice ages in Earth’s history lasted only a few million years.
But the Sturtian glaciation persisted for nearly 60 million years—far longer than any other known ice age.
Scientists now believe this was due to a runaway ice-albedo effect.
Here’s how it works:
- As Earth cooled, more ice formed, reflecting even more sunlight back into space.
- This caused temperatures to drop even further, expanding the ice sheets.
- As the ice continued to grow, it created a feedback loop that locked the planet in a frozen state.
Numerical climate models suggest that once CO2 levels fell below 200 parts per million (ppm)—less than half of today’s levels—the ice-albedo effect became unstoppable. Earth remained a hostile, frozen world for tens of millions of years, with almost no chance of thawing.
What Finally Ended the Ice Age?
If Earth was so deeply frozen, how did it ever escape?
The answer lies in volcanic activity.
Eventually, after millions of years, volcanoes became more active again, pumping CO2 back into the atmosphere.
This gradual increase in greenhouse gases eventually warmed the planet enough to melt the ice sheets, ending the Sturtian glaciation around 660 million years ago.
Professor Dietmar Müller, a co-author of the study, sums it up:
“Geology ruled climate at this time. The prolonged ice age lines up perfectly with a period of extremely low volcanic CO2 outgassing, showing that tectonic forces played a dominant role in shaping Earth’s climate.”
Could This Happen Again?
The findings from this study don’t just explain Earth’s past—they could also offer a glimpse into the future. \
Dr. Dutkiewicz warns that our planet is currently on a trajectory of lower volcanic CO2 emissions due to slowing plate tectonics.
Could this mean Earth is heading for another deep freeze in the distant future?
Possibly—but there’s a catch. Geological processes unfold over millions of years, while human activity is altering the climate in just centuries.
The burning of fossil fuels is rapidly increasing CO2 levels, counteracting any natural cooling trend that might occur due to tectonic shifts.
Why Understanding the Past Matters for the Future
Studying ancient ice ages like the Sturtian glaciation helps scientists predict how CO2 levels, tectonics, and climate interact.
It reinforces an important lesson: while natural forces have shaped Earth’s climate over millions of years, human-induced changes are happening at an unprecedented rate.
Understanding these complex interactions will be critical as scientists refine climate models and explore solutions for the modern climate crisis.
The Sturtian glaciation is a stark reminder of how small shifts in Earth’s natural systems can lead to dramatic and long-lasting consequences—something that should not be ignored as we navigate the future of our warming planet.
