Brains
A new study by Earth scientists at the Harvard John A. Paulson School of Engineering and Applied Sciences is offering a fascinating new explanation for one of Earth’s greatest climate mysteries: how our planet remained locked in a deep freeze for an astonishing 56 million years during the ancient Sturtian glaciation. To put that into perspective, modern humans have existed for only about 300,000 years. Dinosaurs would not appear for another 400 million years after this event.
The Sturtian glaciation unfolded during the Cryogenian Period, roughly 717 to 660 million years ago, at a time when Earth may have resembled a giant frozen snowball drifting through space. And while we technically still live in an “ice age” today —defined scientifically as any long period with permanent polar ice caps — the world during the Sturtian glaciation was something entirely different. Ice may have extended from the poles all the way to the equator, covering oceans and continents alike in what scientists call a “Snowball Earth.”
The research is published in Proceedings of the National Academy of Sciences and led by graduate student Charlotte Minsky. The research was advised by co-author Robin Wordsworth, the Gordon McKay Professor of Environmental Science and Engineering and Professor of Earth and Planetary Sciences, and David T. Johnston and Andrew H. Knoll. Minsky is currently a PhD candidate studying planetary climate evolution in Robin Wordsworth’s group at Harvard.
This age of Earth’s geological time period has raised questions about how life was able to continue to survive during this time, and why it lasted longer than standard climate models have predicted. The Harvard University researchers say that the Earth may not have been in a constant state of “Snowball Earth”, but instead, had gone through periods of fluctuation between being ice-covered and ice-free states.
The research team used a coupled model of the ancient climate and the global carbon cycle. The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere, according to the National Oceanic and Atmospheric Administration. The Earth and its atmosphere form a closed environment; the amount of carbon in this system does not change. Where the carbon is located in the atmosphere or on Earth is constantly in flux.
Carbon is the foundation of all life on Earth, required to form complex molecules like proteins and DNA. This element is also found in our atmosphere in the form of carbon dioxide (CO2). Carbon helps to regulate the Earth’s temperature, makes all life possible, is a key ingredient in the food that sustains us, and provides a major source of energy to fuel our global economy.
Minsky and the research team explain that there were volcanic eruptions that happened just before the Sturtian glaciation in the volcanic region of the Franklin Large Igneous Province (FLIP) in northern Canada. The intense weathering of basalt from the eruptions drew down atmospheric carbon dioxide enough to trigger multiple global glaciations. This glacial onset with one of the largest magmatic episodes in the geological record, the Franklin large igneous province. The FLIP is a massive Neoproterozoic volcanic province that covers over 420,000 square miles (1.1 million km²).
What the team is suggesting is that there were periods of warming and cooling during this time, and it was not just one continuous ice age. As carbon dioxide was released into the atmosphere by the volcanic eruptions, it caused the climate to warm. This would cause the ice to melt, and the basalt would be exposed again and then pull the carbon dioxide out of the atmosphere and cause the planet to cool again. This repeating cycle of carbon dioxide-driven freezing and thawing could naturally sustain the freezing and thawing cycles over tens of millions of years. In short, the weathering of the basalt in the Franklin igneous province would have caused Earth to enter a limit cycle regime, alternating between Snowball and hothouse states during that period.
It may be a surprise to some, but rocks, especially limestone and basalt, can pull carbon out of the atmosphere and counter global warming. In fact, that is why Sunrock Industries and Lithos Carbon from North Carolina have partnered together for a carbon removal project to combat global warming.
The partnership calls the program “enhanced rock weathering technology,” and it involves finding a new use for the rock dust from Sunrock Industries’ Butner basalt mine. Until now, the dust was considered a waste product and was discarded near the mine until the pile stood about 120 feet tall. The dust is now being removed and spread onto farms.
“What makes this partnership particularly exciting is that we’re turning what was once considered excess quarry material into a powerful tool for climate action,” Culpepper said. “The first trucks of Butner rock fines began delivering to local properties in late October 2022, initiating carbon dioxide removal immediately. With growing demand for permanent carbon removal, we see this as a scalable new use for our high-quality basalt,” Alex Culpepper, vice president of corporate business development at Sunrock Industries, wrote in a press release.
The fine basalt rock contains minerals that remove the carbon dioxide in the air and is spread across farmland. The rock particles interact with moisture and atmospheric carbon to initiate mineral weathering. That’s an accelerated version of a natural process Earth has used for billions of years to manage carbon levels, according to the press release.
This Harvard study resolves several longstanding paradoxes, the most important of which was explaining how this period lasted so long. The study also explained the sedimentary patterns from that time period and explained how atmospheric oxygen levels could have remained stable despite extreme climate upheavals. This is important because it explains how life survived during this period of Earth’s history. This scenario resolves the duration problem, is allowable given the currently observed patterns of sedimentation, and predicts syn-Sturtian oxygen stability, according to the research.
