Scientists have for long tried to predict when Earth’s next ice age might arrive. Early estimates suggested it could happen about 11,000 years from now. But the latest research says human-caused global warming has changed the equation, making those predictions far less certain.
Significantly, the Earth’s climate has been quite stable over the past 11,000 years, facilitating evolution of human civilization.
Before the past 11,000 years an ice age on the planet lasted for tens of thousands of years. Over millions of years the Earth experienced a series of ice ages followed by relatively short periods of warmer temperatures.
To understand what might happen next, scientists look to the distant past. For much of Earth’s history, the planet’s temperature has been balanced by the slow breakdown of certain rocks called silicate rocks.
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A report in Science Daily explains that when rainwater absorbs carbon dioxide (CO₂) from the air and falls on these rocks, it slowly wears them down. This process releases carbon and calcium, which wash into the oceans and form materials like shells and limestone. Over millions of years, these materials lock carbon away on the seafloor, helping keep Earth’s temperature in check.
“When the planet gets warmer, rocks break down faster and absorb more CO₂, which helps cool the Earth again,” explains researcher Dominik Hülse.
Recently, studies, documentaries and science fiction movies have also renewed interest if, and when might the next ice age happen, and how the climate change might impact what happens in the future.
Adding to the curiosity is the fact that the planet’s history isn’t all smooth sailing.
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At times, Earth froze completely, turning into what scientists call a “Snowball Earth.” The usual rock-weathering process alone couldn’t explain these extreme deep freezes — something else had to be at play.
A key part of the mystery lies in the oceans. When CO₂ levels rise and the planet warms, more nutrients like phosphorus wash into the sea. These nutrients trigger huge algae blooms — rapid growths of tiny, plant-like organisms that live in water.
Algae play a vital role in Earth’s ecosystems. They make their own food from sunlight, produce much of the planet’s oxygen, help purify water, and form the base of the ocean food chain. Importantly, when algae perish, they sink to the seafloor, carrying the carbon they absorbed with them.
But in warmer conditions, this process can spiral out of control. Fast-growing algae use up oxygen in the water. With less oxygen available, phosphorus that would normally stay buried gets recycled back into the water — feeding even more algae. This feedback loop—more nutrients, more algae, less oxygen—can trap vast amounts of carbon in ocean sediments. Over time, that can lead to dramatic global cooling.
To study these interactions, Hülse and his colleague Andy Ridgwell developed an advanced computer model that simulates Earth’s climate system in detail. Their model revealed that instead of gradually returning to balance after warming, the planet can sometimes “overshoot” and cool far below its original temperature — even enough to trigger an ice age.
Their findings suggest that in Earth’s distant past, when the atmosphere contained much less oxygen, this nutrient feedback loop was even stronger. It may have been powerful enough to cause some of the severe ice ages that marked early geological history.
Today, humans are releasing CO₂ at an unprecedented rate, pushing global temperatures upward. According to Hülse and Ridgwell’s model, Earth could again experience a long-term cooling “overshoot” in the far future — but it would be far milder than before. That’s because today’s higher oxygen levels weaken the feedback loop that once sent the planet into deep freeze.
Still, that’s little comfort for the present.
As Ridgwell points out per Science Daily report, “At the end of the day, does it really matter much if the start of the next ice age is 50, 100, or 200 thousand years into the future? We need to focus now on limiting ongoing warming. The Earth’s natural cooling won’t happen fast enough to save us.”
Huma Nisar is Associate Editor at Views and News. She also writes opinion articles on health, society and diet.
