Volcanoes may have trapped Earth in a 56-million-year ice age, according to a new study that challenges conventional climate models. The research, led by Charlotte Minsky, a graduate student at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), suggests that volcanic activity played a crucial role in the Sturtian glaciation, a 56-million-year-old ice age that defied existing equations. This finding has significant implications for our understanding of Earth's climate history and the potential habitability of other rocky planets.
The Sturtian Glaciation: A Mystery Unveiled
The Sturtian glaciation, named after ancient glacial deposits in Australia, occurred during the Cryogenian period, approximately 717 to 660 million years ago. This period is known as 'Snowball Earth,' a time when the planet experienced a prolonged and intense ice age. The standard climate models, however, struggled to explain this extended glaciation, which lasted 14 times longer than the shorter Marinoan glaciation.
Minsky and her team focused on the Franklin Large Igneous Province, a vast volcanic feature in Canada, to explain this discrepancy. They proposed that volcanic eruptions around 717 million years ago, in what is now the high Arctic, released massive amounts of lava and fresh basalt, which had a profound impact on the atmosphere.
Carbon Dioxide Removal and the Ice Age
The key to this puzzle lies in the ability of fresh basalt to remove carbon dioxide from the atmosphere. When exposed to rain and air, basalt reacts with atmospheric carbon dioxide, leading to the leaching of minerals into rivers and oceans. This process, known as basalt weathering, acts as a powerful long-term climate thermostat.
The team's earlier work, published in 2025, demonstrated that the chemistry of cooling basalt could pull enough carbon dioxide from the atmosphere to trigger a global freeze. This single freeze, however, did not account for the 56-million-year Sturtian glaciation. Minsky's model introduces a cyclical process.
Cyclical Ice Ages and the Franklin Field
Minsky's simulation suggests that as the ice retreated, fresh basalt from the Franklin field, only partly weathered, became exposed again. This restart of the chemical process led to the pull-down of carbon dioxide, triggering another freeze. These cycles, according to the team, repeated multiple times across the Sturtian's 56-million-year span.
This cyclical pattern helps explain the glacial advance and retreat patterns observed in sedimentary deposits found on every continent. Each warm interval would have left behind ordinary marine sediments, while ice-covered stretches would pile up new glacial debris.
Implications for Life and Climate
The study has significant implications for understanding the persistence of aerobic life during the Cryogenian period. Shorter freezes separated by ice-free intervals allow plants and microbes to recharge the atmosphere with oxygen, preventing its depletion. This finding aligns with the fossil record, which shows oxygen-breathing life persisting throughout the Cryogenian.
Beyond Earth: Volcanic Influence on Other Planets
The implications of this research extend far beyond Earth. With the discovery of rocky planets in habitable orbits and the common occurrence of massive volcanic events on other rocky worlds, similar volcanic activity could have driven repeated cycles of freezing on these planets.
This study challenges the assumption of stable habitability, suggesting that it may be far less stable than previously thought. The findings highlight the potential influence of volcanic activity on the climate and habitability of distant worlds, opening up new avenues for exploration in astrobiology and planetary science.
