Modelling the long-term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day

Mills, Benjamin J. W.; Krause, Alexander J.; Scotese, Christopher R.; Hill, Daniel J.; Shields, Graham; Lenton, Timothy M.

doi:10.1016/j.gr.2018.12.001

Cited by 128 publications

(118 citation statements)

References 112 publications

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“…The model is set up for the late Permian by reducing the solar constant to that of 250 Ma, and increasing the background tectonic CO 2 degassing rate to 1.5 times the present day (D = 1.5), in line with estimates for the Late Permian 41 . To obtain the observed pre-event ocean-atmosphere δ 13 C composition of 3.5‰, we set the rate of land-derived organic carbon burial to 20% higher than present day, and adjust the composition of the weathered carbonate reservoir to 3‰.…”

Section: Resultsmentioning

confidence: 99%

Permo–Triassic boundary carbon and mercury cycling linked to terrestrial ecosystem collapse

et al. 2020

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Records suggest that the Permo-Triassic mass extinction (PTME) involved one of the most severe terrestrial ecosystem collapses of the Phanerozoic. However, it has proved difficult to constrain the extent of the primary productivity loss on land, hindering our understanding of the effects on global biogeochemistry. We build a new biogeochemical model that couples the global Hg and C cycles to evaluate the distinct terrestrial contribution to atmosphereocean biogeochemistry separated from coeval volcanic fluxes. We show that the large shortlived Hg spike, and nadirs in δ 202 Hg and δ 13 C values at the marine PTME are best explained by a sudden, massive pulse of terrestrial biomass oxidation, while volcanism remains an adequate explanation for the longer-term geochemical changes. Our modelling shows that a massive collapse of terrestrial ecosystems linked to volcanism-driven environmental change triggered significant biogeochemical changes, and cascaded organic matter, nutrients, Hg and other organically-bound species into the marine system.

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Section: Resultsmentioning

confidence: 99%

Permo–Triassic boundary carbon and mercury cycling linked to terrestrial ecosystem collapse

et al. 2020

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“…This suggests first-order estimates of carbon flux at arcs could be made for the Neoproterozoic and Palaeozoic using only calculations of plate boundary length and convergence rate, analogous to arguments made for episodic zircon age spectra . This formulation could provide important constraints for modeling of palaeoclimate and biogeochemical processes during these times (Lenton et al, 2018;Mills et al, 2019).…”

Section: Dynamic Drivers Of Carbon and Serpentinite In Ocean Basinsmentioning

confidence: 99%

Tectonic Controls on Carbon and Serpentinite Storage in Subducted Upper Oceanic Lithosphere for the Past 320 Ma

2019

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The subduction of upper oceanic lithosphere acts as a primary driver of Earth's deep carbon and water cycles, providing a key transportation mechanism between surface systems and the deep Earth. Carbon and water are stored and transported in altered oceanic lithosphere. In this study, we present mass estimates of the subducted carbon and serpentinite flux from 320 to 0 Ma. Flux estimates are calculated using a fullplate tectonic reconstruction to build a descriptive model of oceanic lithosphere at points along mid-ocean ridges. These points then track the kinematic evolution of the lithosphere until subduction. To address uncertainties of modeled spreading rates in synthetic ocean basins, we consider the preserved recent (83-0 Ma) spreading history of the Pacific Ocean to be representative of the Panthalassa Ocean. This analysis suggests present-day subducting upper oceanic lithosphere contains 10-39 Mt/a of carbon and 900-3500 Mt/a of serpentinite (∼150-450 Mt/a of water). The highest rates of carbon delivery to trenches (20-100 Mt/a) occurred during the Early Cretaceous, as upper oceanic lithosphere subducted during this period formed in times of warm bottom water and the Cretaceous period experienced high seafloor production and consumption rates. Additionally, there are several episodes of high serpentinite delivery to trenches over the last 100 Ma, driven by extensive serpentinization of mantle peridotites exposed at slow spreading ridges. We propose variations in subduction regimes act as the principal control on the subduction of carbon stored in upper oceanic lithosphere, as since 320 Ma the volume of stored carbon across all ocean basins varies by less than an order of magnitude. For pre-Pangea times (<300 Ma), this suggests estimates of seafloor consumption represent a reasonable first-order approximation of carbon delivery. Serpentinite and associated water flux at subduction zones appear to be primarily controlled by the spreading regime at mid-ocean ridges. This is apparent during times of supercontinent breakup where slow spreading ridges produce highly serpentinized crust, and is observed in the present-day Atlantic, Arctic and Indian oceans, where our model suggests upper oceanic lithosphere is up to ∼100 times more enriched in serpentinite than the Panthalassa and Pacific oceans.

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“…Sea surface temperature from Mills et al . ( 37 ) (red and blue, updated GEOCARBSULF and COPSE models) and Trotter et al . ( 38 ) (orange).…”

Section: Resultsmentioning

confidence: 98%

Quantifying ecospace utilization and ecosystem engineering during the early Phanerozoic—The role of bioturbation and bioerosion

et al. 2020

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The Cambrian explosion (CE) and the great Ordovician biodiversification event (GOBE) are the two most important radiations in Paleozoic oceans. We quantify the role of bioturbation and bioerosion in ecospace utilization and ecosystem engineering using information from 1367 stratigraphic units. An increase in all diversity metrics is demonstrated for the Ediacaran-Cambrian transition, followed by a decrease in most values during the middle to late Cambrian, and by a more modest increase during the Ordovician. A marked increase in ichnodiversity and ichnodisparity of bioturbation is shown during the CE and of bioerosion during the GOBE. Innovations took place first in offshore settings and later expanded into marginal-marine, nearshore, deep-water, and carbonate environments. This study highlights the importance of the CE, despite its Ediacaran roots. Differences in infaunalization in offshore and shelf paleoenvironments favor the hypothesis of early Cambrian wedge-shaped oxygen minimum zones instead of a horizontally stratified ocean.

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Modelling the long-term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day

Cited by 128 publications

References 112 publications

Permo–Triassic boundary carbon and mercury cycling linked to terrestrial ecosystem collapse

Permo–Triassic boundary carbon and mercury cycling linked to terrestrial ecosystem collapse

Tectonic Controls on Carbon and Serpentinite Storage in Subducted Upper Oceanic Lithosphere for the Past 320 Ma

Quantifying ecospace utilization and ecosystem engineering during the early Phanerozoic—The role of bioturbation and bioerosion

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