Recent research suggests that our planet may react to rising carbon dioxide (CO2) levels in a surprising way. Instead of facing a delay, the next ice age could arrive right on schedule. This shift is linked to a newly discovered “thermostat” that could efficiently store carbon in the ocean, potentially reversing human emissions within 100,000 years.
Scientists previously thought that natural processes would take much longer—around 500,000 to a million years—to manage excess CO2. The research was detailed in a study published in Science.
Andy Ridgwell, a geology professor at the University of California, Riverside, explains that if both the old and new thermostats work together, the ice age may start sooner than anticipated. However, this doesn’t mean we’ll be safe from climate change’s impacts in the near future. Dominik Hülse, a researcher at the University of Bremen, points out that we are still at risk for the next 1,000 years.
Earth has unique ways of regulating its climate over geological timescales. The process called silicate weathering captures CO2 from the atmosphere via rain. Once the CO2 interacts with silicate rocks, it eventually forms limestone on the ocean floor, locking away carbon for millions of years. Strikingly, this feedback system is activated by increased rainfall, which is more common when temperatures rise.
But what about extreme climate events? Silicate weathering doesn’t account for every fluctuation we observe, such as dramatic ice ages or the planet’s total freeze during “snowball Earth” events. Hülse notes that if silicate weathering were the sole regulator, these extreme conditions would be less likely.
There’s also an emerging idea of a second thermostat linked to phosphorus. Hülse’s research showed that after volcanic eruptions, significant amounts of organic carbon are buried in ocean sediments. This points to a relationship between atmospheric CO2 levels and how carbon is stored in the ocean.
Phosphorus is released into the ocean from weathered rocks and becomes a crucial nutrient for phytoplankton. When these tiny organisms die, they carry organic carbon to the seafloor. This cycle leads to more phytoplankton blooms, which in turn absorb more CO2 from the air, effectively cooling the planet.
Interestingly, while warmer oceans allow for more nutrient recycling, they also hold less oxygen. This can lead to phosphorus being released back into the ocean instead of being deposited. Yet, this process makes the oceans more productive over time, continuing to draw down CO2 even as they release phosphorus.
Experts suggest that this second thermostat could correct for climate changes faster than we think. Previous studies indicated that human emissions might push the next ice age back by tens of thousands of years. However, if this organic carbon thermostat is as effective as the research suggests, we might see the return of CO2 to normal levels much sooner.
Ultimately, while there’s still much to learn about these natural mechanisms, they could reshape our understanding of climate change and its effects on our planet over time.
