Cycle Feedback may also explain the extreme glaciations of early Earth: Earth’s natural “self-correction” will not be fast enough to halt the consequences of ongoing warming.
A new study suggests that the Earth may be overreacting to global warming, and that this could eventually lead to a new Ice Age.
For a long time, scientists believed that the planet’s main climate self-regulation mechanism was the weathering of silicates. In this natural process, rain absorbs carbon dioxide (CO₂) from the atmosphere and, when it falls on rocks, it causes chemical reactions that release minerals and transport carbon and calcium to the oceans. These elements end up forming shells and reefs, and are then deposited at the bottom of the sea, where carbon is stored for millions of years. When the planet warms, rocks wear down faster and absorb more CO₂, which helps cool the Earth again.
However, there are periods in geological history when the planet was almost completely covered by ice — phenomena that the wear of rocks alone cannot justify, explains .
This is where the September 25th investigation in Science comes in, pointing to another decisive factor: the way carbon is stored at the bottom of the ocean.
As atmospheric CO₂ and temperatures increase, more nutrients — especially phosphorus — reach the oceans, feeding the algae growth that capture carbon through photosynthesis. When these algae die, they settle on the seabed, taking the carbon with them.
But this process creates a cycle feedback. In a warmer ocean with greater algal blooms, oxygen levels decrease, which prevents phosphorus from being stored in sediments and causes it to return to the water. The result is an intensification of the growth of algal populations, which consumes even more oxygen and promotes the burial of large amounts of carbon — leading to a global cooling.
The computational model developed by the authors of the new study shows that this balance is not gradual: the Earth system may end up “overcompensating” for warming and cooling beyond the initial point, triggering a Ice Age that can last hundreds of thousands of years.
According to researchers, this type of dynamics could explain the extreme glaciations of the early Earth, when the atmosphere contained less oxygen and nutrient cycles were more intense.
The authors reinforce the need to limit CO₂ emissions, as the Earth’s natural “self-correction” will not be fast enough to halt the consequences of ongoing warming.
