A groundbreaking new study in Earth sciences is reshaping how scientists understand the complex relationship between weathering processes on land and the ocean floor, revealing that these natural mechanisms are intricately connected and together play a critical role in regulating atmospheric carbon dioxide. Traditionally studied as separate entities, weathering reactions—from towering mountain ranges through river sediments down to the ocean depths—constitute a dynamic continuum that governs the long-term sequestration or release of CO2, a key greenhouse gas influencing global climate. This holistic perspective is forcing researchers to rethink how Earth’s silicate weathering functions as a planetary thermostat, with broad implications for climate mitigation strategies.
Weathering is fundamentally a chemical and physical process where rocks break down through interactions with water, atmospheric gases, and biological activity. Silicate minerals, abundant in the Earth’s crust, react with dissolved CO2 and water to form bicarbonates and carbonate ions. These ions eventually precipitate as calcium carbonate, either accumulating in soil systems or settling in ocean basins, effectively locking away carbon from the atmosphere for geological timescales. Until recently, the terrestrial and marine aspects of this carbon sink were assessed in isolation, obscuring the full complexity of carbon flux within the Earth system.
The new research, published in the prestigious journal Nature Geoscience, provides compelling evidence linking marine weathering processes on the seafloor directly to the intensity of chemical weathering occurring on land. This interconnection is crucial because sediments delivered from continents to the ocean are not chemically inert—they continue to undergo transformations that can either enhance or negate the initial carbon sequestration initiated on land. This realization demands a paradigm shift in how weathering is conceptualized; it is not merely a terrestrial phenomenon but rather a seamless, planet-wide continuum influencing carbon dynamics.
One of the most significant discoveries addresses the phenomenon of “reverse weathering” occurring in marine sediments. Unlike conventional weathering which consumes atmospheric CO2, reverse weathering reactions can release CO2 back into the water column, and potentially the atmosphere, by breaking down carbonates formed during upstream processes. This counterintuitive mechanism highlights a potential feedback loop that could diminish or even neutralize net carbon removal achieved by natural or human-accelerated weathering. The fine balance between these forward and reverse processes remains poorly constrained, emphasizing the urgency for further targeted research.
Enhanced weathering technologies, proposed as climate intervention measures to accelerate silicate rock weathering and capture carbon dioxide, become far more complex in light of these findings. Accelerated rock weathering on land, while initially sequestering CO2, risks transporting reactive sediments to the ocean where reverse weathering might undermine carbon removal efforts. Researchers caution that the full lifecycle of weathering and sediment transport must be accounted for to accurately estimate the net climate benefit of these geoengineering approaches, underscoring the gap in our understanding of Earth’s carbon cycle intricacies.
Jeremy Rugenstein, an associate professor at Colorado State University and co-author of this study, explains, “If weathered material reaches the ocean and participates in reverse weathering reactions, the CO2 removal achieved on land might be canceled out. The extent of this reversal is a major unknown, representing a significant risk for enhanced weathering as a carbon removal strategy.” This nuanced view challenges the optimistic outlook on deploying enhanced weathering at scale without comprehensive oceanic sediment studies.
The study integrates geological, chemical, and oceanographic data, utilizing a multidisciplinary approach to map the pathways of carbon as it journeys through weathering reactions from mountainous terrains to deep marine environments. Employing isotope geochemistry and sediment analysis, the research sheds light on previously unrecognized processes modulating carbon fluxes at the land-ocean interface. This integrated perspective opens new frontiers in Earth system science by coupling terrestrial and marine biogeochemical cycles more explicitly than ever before.
Understanding weathering as a continuum is especially relevant in the context of climate change. As global temperatures rise and precipitation patterns shift, weathering rates on land are expected to change, influencing the amount and composition of sediments transported to the ocean. Any alteration in these dynamics could have a feedback effect on atmospheric CO2 levels, either mitigating or exacerbating climate change. Therefore, incorporating the continuum model into predictive climate models will enhance accuracy and improve policy-making for carbon management strategies.
Ocean floor weathering processes also have the added complexity of being influenced by physical oceanography, such as currents, sediment deposition, and biological activity. The interactions between mineral dissolution, sediment compaction, and microbial mediation in marine sediments contribute to the geochemical transformations that dictate carbon storage versus release. These multifaceted processes highlight the interdisciplinary challenges facing researchers attempting to quantify the net effect of weathering on the global carbon budget.
The implications of this comprehensive weathering continuum extend beyond academic curiosity. Carbon capture and sequestration technologies receive significant attention as parts of global efforts to curb carbon emissions. However, technologies predicated on accelerating natural processes must be vetted against the full ecological and geochemical lifecycle to avoid unintended consequences. This study urges caution and rigorous environmental assessment before large-scale deployment of enhanced weathering and other geoengineering techniques aimed at climate mitigation.
Further research is urgently needed to elucidate the quantitative role of reverse weathering and to better understand the temporal scales over which weathered sediments evolve chemically after leaving terrestrial environments. Site-specific studies across diverse geological settings, combined with advanced modeling efforts, will be essential to disentangle the competing processes. Strengthening collaboration between geochemists, oceanographers, and climate scientists will be pivotal for advancing this burgeoning field.
In summary, the Earth’s silicate weathering continuum presents a fundamentally new framework for interpreting the carbon cycle, revealing a delicate equilibrium between carbon uptake on land and potential release in the ocean. Recognizing the Earth system as an interconnected whole rather than disjointed compartments heralds a new era in geoscience research, with vital ramifications for climate science and carbon management policies. As our planet faces unprecedented climate challenges, deepening our understanding of these natural feedback mechanisms becomes not only a scientific pursuit but a cornerstone for sustainable future stewardship.
Subject of Research: Earth’s silicate weathering processes and their role in the global carbon cycle
Article Title: Earth’s silicate weathering continuum
News Publication Date: 7-Aug-2025
Web References:
References: DOI 10.1038/s41561-025-01743-y
Image Credits: Gerrit Trapp-Müller et al.
Keywords: Weathering, Geology, Sedimentology, Erosion, Physical geology, Sediment, Sedimentary rocks, Carbon flux, Carbon cycle, Biogeochemical cycles, Carbon, Carbon dioxide, Carbon capture, Carbon sequestration, Carbon emissions, Carbon sinks, Atmosphere, Sea floor, Earth systems science, Earth surface, Ocean physics, Chemical processes, Geological engineering
