scholarly journals Synchronization of the astronomical time scales in the Early Toarcian: A link between anoxia, carbon-cycle perturbation, mass extinction and volcanism

2018 ◽  
Vol 493 ◽  
pp. 1-11 ◽  
Author(s):  
Fatima-Zahra Ait-Itto ◽  
Mathieu Martinez ◽  
Gregory D. Price ◽  
Abdellah Ait Addi
Keyword(s):  
Carbon Cycle ◽  
Time Scales ◽  
Mass Extinction ◽  
Astronomical Time

Time-scale dependence of climate-carbon cycle feedbacks for weak perturbations in CMIP5 models

2021 ◽  
Author(s):  
Guilherme Torres Mendonça ◽  
Julia Pongratz ◽  
Christian Reick
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Time Scales ◽  
Radiative Forcing ◽  
Global Carbon Cycle ◽  
Atmospheric Co2 ◽  
Ice Age ◽  
Cmip5 Models ◽  
Global Carbon ◽  
Different Time Scales

<p>The increase in atmospheric CO2 driven by anthropogenic emissions is the main radiative forcing causing climate change. But this increase is not only a result from emissions, but also from changes in the global carbon cycle. These changes arise from feedbacks between climate and the carbon cycle that drive CO2 into or out of the atmosphere in addition to the emissions, thereby either accelerating or buffering climate change. Therefore, understanding the contribution of these feedbacks to the global response of the carbon cycle is crucial in advancing climate research. Currently, this contribution is quantified by the α-β-γ framework (Friedlingstein et al., 2003). But this quantification is only valid for a particular perturbation scenario and time period. In contrast, a recently proposed generalization (Rubino et al., 2016) of this framework for weak perturbations quantifies this contribution for all scenarios and at different time scales. </p><p>Thereby, this generalization provides a systematic framework to investigate the response of the global carbon cycle in terms of the climate-carbon cycle feedbacks. In the present work we employ this framework to study these feedbacks and the airborne fraction in different CMIP5 models. We demonstrate (1) that this generalization of the α-β-γ framework consistently describes the linear dynamics of the carbon cycle in the MPI-ESM; and (2) how by this framework the climate-carbon cycle feedbacks and airborne fraction are quantified at different time scales in CMIP5 models. Our analysis shows that, independently of the perturbation scenario, (1) the net climate-carbon cycle feedback is negative at all time scales; (2) the airborne fraction generally decreases for increasing time scales; and (3) the land biogeochemical feedback dominates the model spread in the airborne fraction at all time scales. This last result therefore emphasizes the need to improve our understanding of this particular feedback.</p><p><strong>References:</strong></p><p>P. Friedlingstein, J.-L. Dufresne, P. Cox, and P. Rayner. How positive is the feedback between climate change and the carbon cycle? Tellus B, 55(2):692–700, 2003.</p><p>M. Rubino, D. Etheridge, C. Trudinger, C. Allison, P. Rayner, I. Enting, R. Mulvaney, L. Steele, R. Langenfelds, W. Sturges, et al. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake. Nature Geoscience, 9(9):691–694, 2016.</p>

scholarly journals Decoupled taxonomic and ecological recoveries from the Permo-Triassic extinction

2018 ◽  
Vol 4 (10) ◽  
pp. eaat5091 ◽  
Author(s):  
Haijun Song ◽  
Paul B. Wignall ◽  
Alexander M. Dunhill
Keyword(s):  
Time Scales ◽  
Carrying Capacity ◽  
Mass Extinction ◽  
Marine Species ◽  
Taxonomic Diversity ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Top Down ◽  
Structure Building

The Permian-Triassic mass extinction was the worst crisis faced by life; it killed >90% of marine species in less than 0.1 million years (Ma). However, knowledge of its macroecological impact over prolonged time scales is limited. We show that marine ecosystems dominated by non-motile animals shifted to ones dominated by nektonic groups after the extinction. In Triassic oceans, animals at high trophic levels recovered faster than those at lower levels. The top-down rebuilding of marine ecosystems was still underway in the latest Triassic, ~50 Ma after the extinction, and contrasts with the ~5-Ma recovery required for taxonomic diversity. The decoupling between taxonomic and ecological recoveries suggests that a process of vacant niche filling before reaching the maximum environmental carrying capacity is independent of ecosystem structure building.

scholarly journals Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact

2019 ◽  
Vol 116 (45) ◽  
pp. 22500-22504 ◽  
Author(s):  
Michael J. Henehan ◽  
Andy Ridgwell ◽  
Ellen Thomas ◽  
Shuang Zhang ◽  
Laia Alegret ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Ocean Acidification ◽  
Carbon Isotope ◽  
Primary Productivity ◽  
Deep Sea ◽  
Mass Extinction ◽  
System Modeling ◽  
Earth System ◽  
Ph Gradients ◽  
Chicxulub Impact

Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.

A new Rhaetian δ13Corg record: Carbon cycle disturbances, volcanism, End-Triassic mass Extinction (ETE)

2018 ◽  
Vol 178 ◽  
pp. 92-104 ◽  
Author(s):  
Mariachiara Zaffani ◽  
Flavio Jadoul ◽  
Manuel Rigo
Keyword(s):  
Carbon Cycle ◽  
Mass Extinction

scholarly journals Characteristic disruptions of an excitable carbon cycle

2019 ◽  
Vol 116 (30) ◽  
pp. 14813-14822 ◽  
Author(s):  
Daniel H. Rothman
Keyword(s):  
Mathematical Model ◽  
Carbon Cycle ◽  
Mass Extinction ◽  
Rate Of Change ◽  
Stable Steady State ◽  
Mass Extinctions ◽  
Carbon Mass ◽  
History Of ◽  
External Sources ◽  
Major Disruption

The history of the carbon cycle is punctuated by enigmatic transient changes in the ocean’s store of carbon. Mass extinction is always accompanied by such a disruption, but most disruptions are relatively benign. The less calamitous group exhibits a characteristic rate of change whereas greater surges accompany mass extinctions. To better understand these observations, I formulate and analyze a mathematical model that suggests that disruptions are initiated by perturbation of a permanently stable steady state beyond a threshold. The ensuing excitation exhibits the characteristic surge of real disruptions. In this view, the magnitude and timescale of the disruption are properties of the carbon cycle itself rather than its perturbation. Surges associated with mass extinction, however, require additional inputs from external sources such as massive volcanism. Surges are excited when CO2 enters the oceans at a flux that exceeds a threshold. The threshold depends on the duration of the injection. For injections lasting a time ti≳10,000 y in the modern carbon cycle, the threshold flux is constant; for smaller ti, the threshold scales like ti−1. Consequently the unusually strong but geologically brief duration of modern anthropogenic oceanic CO2 uptake is roughly equivalent, in terms of its potential to excite a major disruption, to relatively weak but longer-lived perturbations associated with massive volcanism in the geologic past.

scholarly journals Sensitivity of atmospheric CO<sub>2</sub> and climate to explosive volcanic eruptions

2011 ◽  
Vol 8 (8) ◽  
pp. 2317-2339 ◽  
Author(s):  
T. L. Frölicher ◽  
F. Joos ◽  
C. C. Raible
Keyword(s):  
Global Warming ◽  
Carbon Cycle ◽  
Surface Temperature ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Time Scales ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Atmospheric Co2 ◽  
Explosive Volcanic Eruptions

Abstract. Impacts of low-latitude, explosive volcanic eruptions on climate and the carbon cycle are quantified by forcing a comprehensive, fully coupled carbon cycle-climate model with pulse-like stratospheric aerosol optical depth changes. The model represents the radiative and dynamical response of the climate system to volcanic eruptions and simulates a decrease of global and regional atmospheric surface temperature, regionally distinct changes in precipitation, a positive phase of the North Atlantic Oscillation, and a decrease in atmospheric CO2 after volcanic eruptions. The volcanic-induced cooling reduces overturning rates in tropical soils, which dominates over reduced litter input due to soil moisture decrease, resulting in higher land carbon inventories for several decades. The perturbation in the ocean carbon inventory changes sign from an initial weak carbon sink to a carbon source. Positive carbon and negative temperature anomalies in subsurface waters last up to several decades. The multi-decadal decrease in atmospheric CO2 yields a small additional radiative forcing that amplifies the cooling and perturbs the Earth System on longer time scales than the atmospheric residence time of volcanic aerosols. In addition, century-scale global warming simulations with and without volcanic eruptions over the historical period show that the ocean integrates volcanic radiative cooling and responds for different physical and biogeochemical parameters such as steric sea level or dissolved oxygen. Results from a suite of sensitivity simulations with different magnitudes of stratospheric aerosol optical depth changes and from global warming simulations show that the carbon cycle-climate sensitivity γ, expressed as change in atmospheric CO2 per unit change in global mean surface temperature, depends on the magnitude and temporal evolution of the perturbation, and time scale of interest. On decadal time scales, modeled γ is several times larger for a Pinatubo-like eruption than for the industrial period and for a high emission, 21st century scenario.

The significance of multiple causes and coincidence in the geological record: from clam clusters to Cretaceous catastrophe

2001 ◽  
Vol 38 (2) ◽  
pp. 271-292 ◽  
Author(s):  
Cameron J Tsujita
Keyword(s):  
Time Scales ◽  
Mass Extinction ◽  
Flood Basalt ◽  
Global Scale ◽  
Causal Mechanism ◽  
Great Expectations ◽  
Geological Record ◽  
Wide Range ◽  
Planktotrophic Larvae ◽  
Mass Extinction Event

Specific causes of unusual events recorded in the geological record are commonly difficult to distinguish and isolate; in some instances, event strata contain features that cannot be explained by a single causal mechanism. Unicausal hypotheses, when applied to complex problems, can lead to the misidentification, misinterpretation, and force-fitting of observations ("great expectations syndrome"). The close timing or temporal overlap of significant events, although statistically improbable on short time scales, becomes possible on long time scales. Event coincidence may occur on a wide range of scales, from local to global. On the local scale, a multiple-event interpretation is offered for both the concentration and clustering of bivalves at specific levels within the Upper Cretaceous Bearpaw Formation of southern Alberta. For this example, the relative timing of fluctuations in benthic substrate texture, oxygen concentration, abundance of planktotrophic larvae, and degree of sea-floor scouring was crucial to the formation and preservation of shell concentrations. On the sharply contrasted global scale, the implications of multiple events warrant much closer consideration than they have received hitherto in terms of major proposed causes for the Cretaceous–Tertiary (K–T) mass-extinction event: bolide impact, sea-level change, climatic change, and flood-basalt volcanism. By considering the predictable effects of these synchronous factors, both individually and in combination, a multiple-cause explanation of the K–T mass extinction emerges as entirely plausible. Certainly it needs to be considered in all future investigations of this important issue.

scholarly journals Sensitivity of atmospheric CO<sub>2</sub> and climate to explosive volcanic eruptions

2011 ◽  
Vol 8 (2) ◽  
pp. 2957-3007 ◽  
Author(s):  
T. L. Frölicher ◽  
F. Joos ◽  
C. C. Raible
Keyword(s):  
Global Warming ◽  
Carbon Cycle ◽  
Surface Temperature ◽  
Time Scales ◽  
Radiative Forcing ◽  
Volcanic Eruptions ◽  
Atmospheric Co2 ◽  
Dynamical Response ◽  
Steric Sea Level ◽  
Explosive Volcanic Eruptions

Abstract. Impacts of low-latitude, explosive volcanic eruptions on climate and the carbon cycle are quantified by forcing a comprehensive, fully coupled carbon cycle-climate model with pulse-like stratospheric sulfur release. The model represents the radiative and dynamical response of the climate system to volcanic eruptions and simulates a decrease of global and regional atmospheric surface temperature, regionally distinct changes in precipitation, a positive phase of the North Atlantic Oscillation, and a decrease in atmospheric CO2 after volcanic eruptions. The volcanic-induced cooling reduces overturning rates in tropical soils, which dominates over reduced litter input due to soil moisture decrease, resulting in higher land carbon inventories for several decades. The perturbation in the ocean carbon inventory changes sign from an initially weak carbon sink to a carbon source. Positive carbon and negative temperature anomalies in subsurface waters last up to several decades. The multi-decadal decrease in atmospheric CO2 yields an additional radiative forcing that amplifies the cooling and perturbs the Earth System on much longer time scales than the atmospheric residence time of volcanic aerosols. In addition, century-scale global warming simulations with and without volcanic eruptions over the historical period show that the ocean integrates volcanic radiative cooling and responds for different physical and biogeochemical parameters such as steric sea level or dissolved oxygen. Results from a suite of sensitivity simulations with different amounts of sulfur released and from global warming simulations show that the carbon cycle-climate sensitivity γ, expressed as change in atmospheric CO2 per unit change in global mean surface temperature, depends on the perturbation. On decadal time scales, modeled γ is several times larger for a Pinatubo-like eruption than for the industrial period and for a high emission, 21st century scenario.

Ecosystem change and carbon cycle perturbation preceded the end-Triassic mass extinction

2021 ◽  
Vol 576 ◽  
pp. 117180
Author(s):  
Ekaterina Larina ◽  
David J. Bottjer ◽  
Frank A. Corsetti ◽  
Alyson M. Thibodeau ◽  
William M. Berelson ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Mass Extinction ◽  
Ecosystem Change

scholarly journals Carbon cycle dynamics following the end-Triassic mass extinction: Constraints from pairedδ13Ccarbandδ13Corgrecords

2012 ◽  
Vol 13 (9) ◽  
Author(s):  
Aviv Bachan ◽  
Bas van de Schootbrugge ◽  
Jens Fiebig ◽  
Christopher A. McRoberts ◽  
Gloria Ciarapica ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Mass Extinction
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