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- Title
EONS: A New Biogeochemical Model of Earth's Oxygen, Carbon, Phosphorus, and Nitrogen Systems From the Archean to the Present.
- Authors
Horne, J. E.; Goldblatt, C.
- Abstract
We present Earth's Oxygenation and Natural Systematics (EONS): a new, fully coupled biogeochemical model of the atmosphere, ocean, and their interactions with the geosphere, which can reproduce major features of Earth's evolution following the origin of life to the present day. The model, consisting of 257 unique fluxes between 96 unique chemical reservoirs, includes an interactive biosphere, cycles of carbon, nitrogen, phosphorus, and oxygen, and climate. A nominal model run initialized in the Eoarchean resolves emergent surface oxygenation, nutrient limitations, and climate feedbacks. The modeled atmosphere oxygenates in stepwise fashion over the course of the Proterozoic; a nearly billion year lag after the evolution of photosynthesis at 3.5 Ga is followed by a great oxidation event at 2.4 Ga, which appears to be caused by the gradual buildup of organic matter on the continents imposing nutrient limitation on the biosphere by removing key nutrients from the ocean system. The simple climate system shows significant temperature shifts punctuate the oxygenation process, implying that major biological transitions possibly destabilized Earth's climate. This work demonstrates that forward modeling the entirety of Earth's history with relatively few imposed boundary forcings is feasible, that the Earth system is not at steady state, and that our understanding of coupled C‐N‐P‐O cycling as it functions today can explain much of the Earth's evolution. Plain Language Summary: The Earth is an interconnected system of biological, geological, and atmosphere‐ocean chemical systems responding to and influencing one another. We have developed a new model of our planet's chemical evolution, Earth's Oxygenation and Natural Systematics (EONS); this first of its kind model encompasses the entire lifetime of Earth's biosphere and major evolutionary developments therein, including the emergence of oxygen producing organisms and the colonization of continents by plants. Our basic (nominal) model run, starting 4 billion years ago and allowing biogeochemical systems to dynamically evolve until the modern day, agrees with geochemical evidence for rising atmospheric oxygen in magnitude and timing. It successfully reproduces atmosphere‐ocean chemistry and geologic systems in the modern context. Model output implies that the delay in oxygen's rise after the evolution of photosynthesis is caused by gradual burial of organic matter onto continents, depriving biological systems of key nutrients. Results also suggest that developments in the biosphere significantly disrupted Earth's climate. This model is a significant step forward in using coupled systematics to describe Earth's long‐term evolution. This work demonstrates that our planet is an immensely intertwined web of chemical relationships in a constant state of change, but one that can be fundamentally disentangled and understood. Key Points: The first fully coupled evolutionary C‐N‐O‐P box model spanning all major eons produces a surface oxygenation curve consistent with proxiesThe biosphere is a primary driver of Earth system evolution; increasing organic carbon burial and nutrient sequestration delay oxygen's riseThe chemical composition of the atmosphere‐ocean is never in steady state, due to the long timescales of geological and stellar evolution
- Subjects
GREAT Oxidation Event; OXYGENATION (Chemistry); ARCHAEAN; BIOLOGICAL systems; EARTH (Planet); CONTINENTS
- Publication
Geochemistry, Geophysics, Geosystems: G3, 2024, Vol 25, Issue 4, p1
- ISSN
1525-2027
- Publication type
Article
- DOI
10.1029/2023GC011252