Chemical reactions on the ocean floor have emerged as the decisive factor in why a global ice age lasted 56 million years, and a subsequent ice age ended in just 4 million years.
The results overturn the long-held assumption that volcanic carbon alone sets the clock for Earth’s most extreme climate conditions.
Compare the two ice ages
Rocks more than 600 million years old record two global freezes that lasted dramatically different periods of time.
By tracking how carbon moves between the ocean and the atmosphere, Trent B. Thomas of the University of Washingtonwisconsin) demonstrated that intensified seafloor weathering can keep greenhouse gases low enough to extend deep freeze conditions for tens of millions of years.
In his simulations, volcanic carbon emissions remained in the same range during both episodes, but only the scenario with accelerated seafloor reactions recreated a prolonged ice age.
The imbalance points from the sky to the ocean floor, raising the need to understand how the ocean floor came to have such enormous control over Earth’s climate clock.
why does the earth remain frozen
Geologists refer to this global deep freeze as Snowball Earth. eventA time when ice spread almost all over the earth, reaching near the equator.
“For such a dramatic difference, something must be very different in the carbon systems between the two snowball Earth events,” said Dr. Trent B. Thomas, a planetary scientist at the University of California.
Volcanoes emit carbon dioxide and provide stabilization. feedback Warm, moist continents accelerate the destruction of rocks, and colder periods slow down rock destruction.
As the ice spreads, its bright surface reflects sunlight back into space, glacier You can continue moving forward even if the onshore thermostat stops.
carbon trapped in the ocean floor
With the continents locked under ice, the destruction of land rocks slowed to a crawl, but seawater still migrated through cracks in the oceanic crust.
That process is called Weathering on the ocean floorseawater reacts with rocks on the ocean floor and captures carbon as minerals.
The release of dissolved ions from these reactions caused carbon-containing minerals to precipitate, allowing the ocean to trap more carbon while lowering atmospheric CO₂ levels.
Although this process plays only a minor role today, Thomas’ model shows that it could become a major carbon sink during global ice sheets lasting millions of years.
Thousands of simulations
To test this idea, a team at the University of California ran 10,000 simulations of the ocean, air, and rocks during a global deep freeze.
the other side studycarbon input from the Earth’s interior remained stable while ocean floor reactions sped up and slowed down.
Only one setting maintained freezing for an extended period of time. Seafloor weathering was approximately 25 to 53 times faster than today, far exceeding the values of short-term freezing.
Their tests kept carbon release rates within modern uncertainties, so most of the timing power of the results was on the ocean floor.
Acidic ocean accelerates reactions
During ice ages, high levels of carbon dioxide made seawater more acidic, causing rocks on the ocean floor to dissolve faster wherever water could reach them.
With rivers blocked by ice, far less mud reached the deep ocean, leaving the old crust exposed to circulating seawater.
Less sediment means less sealing of seafloor cracks, allowing more water to flow and react.
These conditions could make the ocean floor a major carbon sink when the continents freeze and stand still.
Cracks in the rock control the flow
The texture of the rock was important because seawater can only react where it can enter and move into the Earth’s crust.
Scientists call it openness porositya section of rock consisting of connected open spaces.
Near hot underwater vents, certain minerals can solidify in cracks, blocking water flow and slowing reactions.
The more open the Earth’s crust is, the longer it remains reactive, so changes in porosity determine whether the Earth remains frozen for years.
Duration of ice in sulfate form
Ocean chemistry may have controlled the porosity of the Earth’s crust by the amount of sulfate, a sulfur compound dissolved in seawater, available near the vents.
When sulfates are abundant, minerals tend to form in the hot Earth’s crust, plugging cracks and limiting contact between water and rocks.
The paper’s geochemical evidence pointed out that sulfate was almost absent during the long ice age and then recovered before the short ice age.
If this timing holds, small fluctuations in seawater chemistry could determine whether the snowball ends quickly or lasts.
Chemistry trapped in global ice
Low sulfate concentrations and open pores can lead to increased seafloor weathering and the formation of loops that retard thawing.
With fewer minerals to clog, the pores in the Earth’s crust remain open, allowing more seawater to circulate through the rock and sustain reactions.
Long-lasting ice can reduce oxygen in the ocean, keeping sulfate concentrations low.
“This is just meant to start a conversation,” Thomas said after explaining how it was done. marine chemistry It has the potential to control ocean floor reactions.
Ocean chemistry shapes the planet
The planet’s climate may depend more on the chemistry of the ocean floor than scientists had assumed, especially if the surface becomes hostile to the destruction of normal rocks.
In a world covered in ice, greenhouse gas Ice can rise slowly over many years, but chemical reactions on the ocean floor can determine when it retreats.
Even without a full-fledged snowball, the rate at which carbon leaves the atmosphere can change if the ocean cools or if cracks in the ocean floor remain open.
Because modern climate challenges involve faster changes and living ecosystems, this research is primarily about reshaping our thinking at deeper points in time rather than short-term predictions.
A new explanation links periods of ancient global freezing to chemical reactions on the ocean floor that continue to pull carbon from the atmosphere.
Future studies will need rock evidence and geochemical records to determine whether seafloor porosity has indeed changed as predicted by the models.
The research will be published in a journal geology.
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