Scientists have uncovered new evidence linking salt to Earth’s extreme freezing event millions of years ago, while ancient water trapped in salt formations offers insights into ocean history. The findings, drawn from two studies, reveal how salt’s physical properties may have amplified global cooling and preserved clues about ancient atmospheric conditions.
Salt’s Role in Earth’s Deep Freeze
Between 720 and 635 million years ago, Earth experienced a period known as Snowball Earth, when ice covered nearly the entire planet, even the tropics. A study led by researchers at The Arctic University of Norway suggests that salt played a critical role in this extreme freeze. As ocean water froze, salt crystallized on ice surfaces, creating “salt mirrors” that reflected more sunlight than snow or pure ice. This feedback loop, known as ice-albedo, intensified cooling, locking the planet in a deep freeze.
The researchers’ numerical models show that salt acted as an acceleration button for global freezing. More salt on ice surfaces led to more ice formation, which in turn reflected more sunlight, creating a self-reinforcing cycle. This mechanism may explain why Snowball Earth lasted for millions of years, with ice extending far beyond the poles. The study, published in Climate of the Past, highlights how small physical processes can dramatically alter planetary climate systems.
Snowball Earth froze hard. Salt may explain why
Earth Froze More Than Once
The Snowball Earth was not a one-time event. During the Neoproterozoic era, several similar, though less extreme, episodes of global cooling occurred. These periods represent dramatic climatic shifts that likely influenced the evolution of early life. Salt performs many vital functions in nature, including regulating water density, driving ocean circulation, and dictating how heat moves through the seas. All these factors directly influence the global climate system.
Ancient Water in Salt Reveals Ocean Secrets
Meanwhile, a separate study analyzing 150-million-year-old water trapped in salt formations has provided insights into Earth’s ancient oceans. Geochemists Mebrahtu Weldeghebriel of Princeton University and Binghamton University, and Tim Lowenstein of Binghamton University, examined lithium levels in marine halite (rock salt) to reconstruct past atmospheric and oceanic conditions. Their findings, published in a new study, reveal a direct link between ocean chemistry and atmospheric changes over time.
There is a close link between ocean chemistry and atmospheric chemistry, said Mebrahtu Weldeghebriel, one of the study’s authors. Whatever changes happen in the ocean also reflect what’s happening in the atmosphere.
The research shows that tectonic activity influenced lithium levels in seawater, which in turn affected global carbon dioxide levels and climate shifts. This connection helps explain how Earth’s geological and atmospheric systems have evolved together over eons.
150 million year old water trapped in salt contains
The study analyzed 639 samples of marine halite from 65 halite crystals dating back 150 million years. The presence of lithium was critical because it indicates hydrothermal activity. As tectonic plate activity declined, there was a global drop in lithium levels. Instead, it was replaced by a rise in magnesium and calcium. The reduction in activity would also have meant less carbon dioxide being released into the atmosphere, which could have been a factor in the temperature drop leading to the ice age.
Implications for Climate Science and Earth’s History
Both studies underscore the interconnectedness of Earth’s systems. The Snowball Earth research highlights how salt’s reflective properties could have triggered a runaway cooling effect, while the ancient water analysis demonstrates how geological processes shape atmospheric conditions. These findings challenge previous assumptions about the sensitivity of Earth’s climate to minor physical changes.
For modern climate science, the studies emphasize the importance of incorporating nuanced processes like salt-ice interactions into climate models. Understanding these ancient mechanisms could improve predictions about future climate shifts. As Tim Lowenstein, another study author, noted, Everything is connected.
This principle, revealed through salt’s dual role in freezing and preserving ancient water, offers a deeper perspective on Earth’s climatic resilience and complexity.
The research also raises questions about how similar processes might influence other planets. If salt can drive extreme climate changes on Earth, could it play a similar role on icy moons or exoplanets? For now, the findings remain rooted in Earth’s distant past, but their implications for climate science and planetary understanding are profound.
