According to a new Science study, global warming may paradoxically push Earth towards a future Ice Age. This is not because the Earth will cool directly but rather by creating a chain reaction in the deep oceans.
Dominik Hulse, Andy Ridgwell and other researchers developed an advanced model of the Earth’s system to determine how long-term climate thermostats respond to large amounts of carbon dioxide in the atmosphere. The researchers’ findings suggest an unanticipated possibility. If warming is extreme enough, this could activate chemical and biological feedback cycles that cause runaway cooling.
Scientists believed that the Earth’s main climate stabilizer was slow weathering silicate rock for decades. Weathering removes CO2 naturally as temperatures increase, and over thousands of years, this balance is restored. The new study shows that an additional thermostat, organic carbon burial in oceans, can overpower this system.
The model Science suggests that a high concentration of CO2 will initially warm the earth, leading to increased rainfall, erosion and phosphorus being transported from the land into the sea. This influx of nutrients supercharges the marine life and boosts biological productivity around the world. More organic material sinks and decomposes on the ocean floor as more life forms. This slowly strips oxygen away from the deep sea.
As oxygen levels drop, the seafloor releases phosphorus into the water. This process increases productivity. This sets in motion a self-reinforcing cycle: More nutrients, increased growth, and more carbon stored in the sediments. The level of CO2 is also rapidly decreasing.
CO2 levels eventually drop below their starting point in the simulations. Initial warming turns into a global cooling. Earth’s temperature average could drop by 6 degrees Celsius depending on the oxygen level. This is a larger shift than between the current climate and that of the last Ice Age.
The authors noted that “overcooling” is more pronounced at intermediate oxygenation levels of oceans and atmospheres. This provides a linkage between the major oxygenation transitions during the Precambrian period and extreme Earth cooling events.
It also highlights an ironic twist. The same microbial forces that helped form Earth’s atmospheric could also destabilize the atmosphere. The biological feedback can push the Earth past the breaking point by outpacing slower rock weathering.
Scientists may have underestimated the fragility of planetary stability if multiple climate regulators collide and overpower one another.
The study’s central message, even though it focuses on geological times beyond human influence, is that climate systems are capable of acting in non-linear, unexpected ways. The right conditions could cause extreme warming to create its own icy breakdown, proving that Earth’s future is far more complex than a world steadily heating up.
