Studies reevaluate reverse weathering process, shifts understanding of global climate

Two new publications remap the understanding of reverse weathering in the scientific community. The Dauphin Island Sea Lab’s Senior Marine Scientist, Dr. Jeffrey Krause, played a key role in both projects, which include several collaborating institutions. 

Reverse weathering is one of the ocean’s most important yet least understood geochemical processes.  During this natural process, dissolved minerals and chemicals combine to form new clay minerals in seafloor sediments.  These reactions greatly influence the marine silicon cycle and Earth’s climate because they take dissolved elements, like lithium, iron, and manganese, into newly forming minerals. 

Silicon is Earth’s second most abundant element in the Earth’s crust and a vital nutrient for many marine organisms such as diatoms. They are a type of microscopic algae that form the base of the ocean food web. When these organisms die, their glass-like shells settle onto the seafloor, where silica continues to transform over time.

For decades, scientists believed reverse weathering was too slow to influence any environmental change on shorter time scales. However, these new studies reveal both the speed at which the process can occur and the biological drivers involved. 

In a laboratory setting, researchers recreated seafloor conditions in [one study](https://www.science.org/doi/10.1126/sciadv.adt3374) to determine the recipe and rates at which authigenic clays can form from biogenic silica, the glass-like material produced by diatoms. What they found is that authigenic clay minerals, which are minerals that form in place within a sediment, can develop in as little as forty days from biogenic silica produced by marine diatoms. Previous estimates suggested that this transformation would take generations. 

“It was just so quick, we were stunned to see how fast this can happen in the laboratory environment,” Krause said. 

This discovery sheds new light on how ocean chemistry regulates carbon dioxide, the ocean’s acidity, and the global climate, as the ocean plays a central role in controlling Earth’s temperature and atmospheric balance. Since carbon dioxide is a significant greenhouse gas, even small variations in how the ocean absorbs or releases it can affect climate stability.  

In the [second study](https://www.nature.com/articles/s43247-025-02941-7), scientists used radioactive silicon tracers and sediment samples from the Mississippi River Plume and the Congo Deep Sea Fan to demonstrate that microorganisms enhanced silica uptake and the formation of sediment rates by a factor of three and a half compared to environments without microbial activity.  

Within days, microbes were able to dissolve existing silica and reform it into new mineral phases, a process that the scientists initially thought would take much longer. Dr. Krause and colleagues found that over half of the reprecipitated silica in marine sediments was the result of microbial activity, while only about a quarter formed through the nonliving reactions. 

These findings expand long-standing assumptions that microbes influence silicon cycling primarily in the water column or in extreme environments, such as hydrothermal vents. 

Together, these two papers represent a significant shift in understanding how reverse weathering is both biologically mediated and occurs much faster than classic models predicted, with important implications for global carbon cycling and the stability of the Earth’s climate system. 

These discoveries show that ocean sediments can influence carbon and nutrient cycles at a faster rate, which directly affects how the ocean can store carbon dioxide. 

For the future, the studies set the path for upcoming advances. Dr. Krause is currently leading two National Science Foundation-funded projects, in collaboration with Dr. Michalopoulos and Dr. Brandi Kiel Reese, to examine the mechanisms of microbially mediated reverse weathering. The work aims to resolve any questions about how life shapes mineral formation, nutrient cycles, and the ocean’s ability to regulate atmospheric carbon dioxide in the long term.

## Publications

*Simin Zhao et al., Rapid transformation of biogenic silica to authigenic clay: Mechanisms and geochemical constraints.Sci. Adv.11,eadt3374. https://doi.org/10.1126/sciadv.adt3374*

*Michalopoulos, P., Krause, J.W., Pickering, R.A. et al. Rapid microbial activity in marine sediments significantly enhances silica cycling rates compared to abiotic processes. Commun Earth Environ 6, 982. https://doi.org/10.1038/s43247-025-02941-7*