•Simulation of impacts of end-Triassic volcanism with an Earth System Model.•Cooling-warming sequences caused by pulsed volcanic sulfur and carbon emissions.•High climatic variability, representing ...stress for ecosystems like coral reefs.
Throughout the history of complex life, Earth's climate and biogeochemical cycles have been perturbed by Large Igneous Province (LIP) volcanism, with several LIP episodes correlating with major mass extinction events. Yet many aspects of the interplay between geological, climatic and ecological processes in the Earth System during these times of global upheaval remain poorly understood. This study focuses on the Central Atlantic Magmatic Province and the associated extinction event in the latest Triassic, about 201 million years ago. Although climate and carbon cycle models successfully reproduce aspects of the end-Triassic environmental changes, many questions regarding the causal and temporal relations behind them remain unresolved. Here, we report an effort to model and quantify the dynamic response of the Earth System to short pulses of volcanogenic volatile emissions for an ensemble of emission scenarios. For the first time in the context of the end-Triassic events, this is done with a coupled climate model and under consideration of both carbon and sulfur emissions. Tested are pulses with ∼1−6 kyr duration during which 2500−7500GtC are emitted and 0−500GtS form stratospheric sulfate aerosols. The simultaneous emission of carbon and sulfur during one pulse of volcanic activity causes climatic fluctuations on annual to millennial timescales: A sequence of transient global cooling and subsequent sustained warming, overprinted with high interannual variability. The simulated maximum global warming ranges from +1.8 to +4.4°C, while the amplitude of cooling is considerably higher in the upper range of the tested sulfur emission scenarios. The magnitude of temperature change varies regionally, being lowest in the Tethys realm. Changes in steric sea level (∼1−3 m) and ocean overturning strength, a surface ocean pH decrease (∼0.2−0.4) and a drop of the carbonate saturation especially in the Tethys are also obtained from the simulations during each emission pulse. By evaluating the simulated temperature changes against thermal tolerance limits of stony corals in a simplified manner, we find that these are not clearly transgressed on a global scale in the simulated warming scenarios. However, the climatic variability potentially introduced by the volcanic forcing would have represented significant stress for marine organisms. This study represents a significant step towards integrating multiple volcanic forcing mechanisms and environmental response processes in space and time to yield a more complete picture of impacts of CAMP volcanism and LIPs in general.
The hydrological change plays a vital role in regulating Earth's surface systems. However, understanding past hydrological variations on land is hindered by difficulties in dating and correlating ...continental strata, and the perceived incompleteness of terrestrial sedimentary successions. Here, we calibrate the astronomical time scale of an Upper Triassic lake sediment succession at St. Audrie's Bay (UK) using recently proposed statistical tuning approaches. A novel statistical completeness evaluation confirms that an optimal correlation of the astronomically calibrated Upper Triassic magnetostratigraphy can be determined between St. Audrie's Bay and well-studied reference sections in the Newark Basin (USA) and Jameson Land Basin (Greenland). Reconstructed lake level changes at St. Audrie's Bay were in-phase with those in the Newark Basin (deposited at a similar tropical paleolatitude), but in anti-phase with those in the high-latitude Jameson Land Basin – a pattern also supported by paleoclimate modeling. A ∼1.8 million-year cyclicity paced hydrological changes in these basins, and represents the fingerprint of chaotic behavior of the Solar System.
•Upper Triassic in St. Audrie's Bay is largely complete at 405-kyr scale.•New statistical approach evaluates the completeness of the sedimentary records.•1.8 Myr cyclicity demonstrates the chaotic behavior of the Solar System.•Sedimentary records and climate modeling depict hydrological response to orbital forcing.
Orbital cyclicity is a fundamental pacemaker of Earth's climate system. The Newark–Hartford Basin (NHB) lake sediment record of eastern North America contains compelling geologic expressions of this ...cyclicity, reflecting variations of climatic conditions in tropical Pangea during the Late Triassic and earliest Jurassic (~233 to 199 Ma). Climate modeling enables a deeper mechanistic understanding of Earth system modulation during this unique greenhouse and supercontinent period. We link major features of the NHB record to the combined climatic effects of orbital forcing, paleogeographic changes, and atmospheric pCO2 variations. An ensemble of transient, orbitally driven climate simulations is assessed for nine time slices, three atmospheric pCO2 values, and two paleogeographic reconstructions. Climatic transitions from tropical humid to more seasonal and ultimately semiarid are associated with tectonic drift of the NHB from ~5 ∘N to 20 ∘N. The modeled orbital modulation of the precipitation–evaporation balance is most pronounced during the 220 to 200 Ma interval, whereas it is limited by weak seasonality and increasing aridity before and after this interval. Lower pCO2 at around 205 Ma contributes to drier climates and could have led to the observed damping of sediment cyclicity. Eccentricity-modulated precession dominates the orbitally driven climate response in the NHB region. High obliquity further amplifies summer precipitation through the seasonal shifts in the tropical rainfall belt. Regions with other proxy records are also assessed, providing guidance toward an integrated picture of global astronomical climate forcing in the Late Triassic and ultimately of other periods in Earth history.
Reconstructing the climate of the past requires archives that bear proxy information on temperature, precipitation, or atmospheric composition, for example. In this study we use contour marks as ...potential water level marks in mud sediments to reconstruct local evaporation rates at the Bromacker lagerstaette site in the Early Permian. The measured values indicate a daily evaporation of 1.5–3.75 mm with a median value of 2.25 mm/day. The calculated evaporation rates are compared with modern ones to estimating moisture, precipitation and seasonal climate. For evaluating reconstructed precipitation and evapotranspiration rates, values simulated by global climate models and calculated from geochemical datasets are furthermore incorporated. For the first time, quantitative data and models elucidate the climate of the Tambach Formation and Bromacker lagerstaette against the background of the pivotal transition from the Carboniferous Ice House to the Permian Hothouse climate. Our results suggest a strongly seasonal climate with wet summers and dry winters in a mountainous region based on unexpectedly low temperatures (10.9–15.0 °C) considering the palaeo-location of the site in the tropical belt during the Early Permian. According to the modern vegetation model by Holdridge a moist forest biome is suggested for the Bromacker lagerstaette.
•Palaeoclimatic assessment of an internationally important lagerstaette.•First quantitative analysis of water level marks as proxies of palaeoevaporation.•Synthesis of proxy data and modelling for the reconstruction of Early Permian climate in Central Europe (Pangaea).
The Mesozoic era (∼252 to 66 million years ago) was a key interval in Earth's evolution toward its modern state, witnessing the breakup of the supercontinent Pangaea and significant biotic ...innovations like the early evolution of mammals. Plate tectonic dynamics drove a fundamental climatic transition from the early Mesozoic supercontinent toward the Late Cretaceous fragmented continental configuration. Here, key aspects of Mesozoic long‐term environmental changes are assessed in a climate model ensemble framework. We analyze so far the most extended ensemble of equilibrium climate states simulated for evolving Mesozoic boundary conditions covering the period from 255 to 60 Ma in 5 Myr timesteps. Global mean temperatures are generally found to be elevated above the present and exhibit a baseline warming trend driven by rising sea levels and increasing solar luminosity. Warm (Triassic and mid‐Cretaceous) and cool (Jurassic and end‐Cretaceous) anomalies result from pCO2 changes indicated by different reconstructions. Seasonal and zonal temperature contrasts as well as continental aridity show an overall decrease from the Late Triassic‐Early Jurassic to the Late Cretaceous. Meridional temperature gradients are reduced at higher global temperatures and less land area in the high latitudes. With systematic sensitivity experiments, the influence of paleogeography, sea level, vegetation patterns, pCO2, solar luminosity, and orbital configuration on these trends is investigated. For example, long‐term seasonality trends are driven by paleogeography, but orbital cycles could have had similar‐scale effects on shorter timescales. Global mean temperatures, continental humidity, and meridional temperature gradients are, however, also strongly affected by pCO2.
Key Points
We assess global long‐term climate trends through the Mesozoic era with an ensemble of climate model simulations
Varying carbon dioxide levels cause anomalies around an overall warming trend due to changing paleogeography and increasing insolation
Seasonal and zonal temperature contrasts as well as aridity decrease with time, while meridional gradients vary with paleogeography
Orbital cyclicity is a fundamental pacemaker of Earth’s climate system. The Newark–Hartford Basin (NHB) lake sediment record of eastern North America contains compelling geologic expressions of this ...cyclicity, reflecting variations of climatic conditions in tropical Pangea during the Late Triassic and earliest Jurassic (~233 to 199 Ma). Climate modeling enables a deeper mechanistic understanding of Earth system modulation during this unique greenhouse and supercontinent period. We link major features of the NHB record to the combined climatic effects of orbital forcing, paleogeographic changes, and atmospheric
p
CO
2
variations. An ensemble of transient, orbitally driven climate simulations is assessed for nine time slices, three atmospheric
p
CO
2
values, and two paleogeographic reconstructions. Climatic transitions from tropical humid to more seasonal and ultimately semiarid are associated with tectonic drift of the NHB from
~
5
°
N
to
20
°
N
. The modeled orbital modulation of the precipitation–evaporation balance is most pronounced during the 220 to 200 Ma interval, whereas it is limited by weak seasonality and increasing aridity before and after this interval. Lower
p
CO
2
at around 205 Ma contributes to drier climates and could have led to the observed damping of sediment cyclicity. Eccentricity-modulated precession dominates the orbitally driven climate response in the NHB region. High obliquity further amplifies summer precipitation through the seasonal shifts in the tropical rainfall belt. Regions with other proxy records are also assessed, providing guidance toward an integrated picture of global astronomical climate forcing in the Late Triassic and ultimately of other periods in Earth history.
Orbital cyclicity is a fundamental pacemaker of Earth's climate system. The Newark-Hartford Basin (NHB) lake sediment record of eastern North America contains compelling geologic expressions of this ...cyclicity, reflecting variations of climatic conditions in tropical Pangea during the Late Triassic and earliest Jurassic (~233 to 199 Ma). Climate modeling enables a deeper mechanistic understanding of Earth system modulation during this unique greenhouse and supercontinent period. We link major features of the NHB record to the combined climatic effects of orbital forcing, paleogeographic changes, and atmospheric
COFormula: see text variations. An ensemble of transient, orbitally driven climate simulations is assessed for nine time slices, three atmospheric
COFormula: see text values, and two paleogeographic reconstructions. Climatic transitions from tropical humid to more seasonal and ultimately semiarid are associated with tectonic drift of the NHB from Formula: see text to Formula: see text. The modeled orbital modulation of the precipitation-evaporation balance is most pronounced during the 220 to 200 Ma interval, whereas it is limited by weak seasonality and increasing aridity before and after this interval. Lower
COFormula: see text at around 205 Ma contributes to drier climates and could have led to the observed damping of sediment cyclicity. Eccentricity-modulated precession dominates the orbitally driven climate response in the NHB region. High obliquity further amplifies summer precipitation through the seasonal shifts in the tropical rainfall belt. Regions with other proxy records are also assessed, providing guidance toward an integrated picture of global astronomical climate forcing in the Late Triassic and ultimately of other periods in Earth history.
Orbital cyclicity is a fundamental pacemaker of Earth's climate system. The Newark-Hartford Basin (NHB) lake sediment record of eastern North America contains compelling geologic expressions of this ...cyclicity, reflecting variations of climatic conditions in tropical Pangea during the Late Triassic and earliest Jurassic (~233 to 199 Ma). Climate modeling enables a deeper mechanistic understanding of Earth system modulation during this unique greenhouse and supercontinent period. We link major features of the NHB record to the combined climatic effects of orbital forcing, paleogeographic changes, and atmospheric pCOFormula: see text variations. An ensemble of transient, orbitally driven climate simulations is assessed for nine time slices, three atmospheric pCOFormula: see text values, and two paleogeographic reconstructions. Climatic transitions from tropical humid to more seasonal and ultimately semiarid are associated with tectonic drift of the NHB from Formula: see text to Formula: see text. The modeled orbital modulation of the precipitation-evaporation balance is most pronounced during the 220 to 200 Ma interval, whereas it is limited by weak seasonality and increasing aridity before and after this interval. Lower pCOFormula: see text at around 205 Ma contributes to drier climates and could have led to the observed damping of sediment cyclicity. Eccentricity-modulated precession dominates the orbitally driven climate response in the NHB region. High obliquity further amplifies summer precipitation through the seasonal shifts in the tropical rainfall belt. Regions with other proxy records are also assessed, providing guidance toward an integrated picture of global astronomical climate forcing in the Late Triassic and ultimately of other periods in Earth history.
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