Deep marine anoxia of the southern Panthalassa during the Permian-Triassic – global impacts of the Siberian Traps

2021 ◽  
Author(s):  
Stephen Grasby ◽  
David Bond ◽  
Paul Wignall ◽  
Runsheng Yin ◽  
Lorna Strachan ◽  
...  
Keyword(s):  
Global Warming ◽  
Ocean Circulation ◽  
Surface Waters ◽  
Mass Extinction ◽  
Bottom Water ◽  
Deep Ocean ◽  
Marine Life ◽  
Siberian Traps ◽  
Southern Latitude ◽  
Global Impacts

<p>The deep-water record of marine anoxia across the Permo-Triassic mass extinction (PTME) is highly controversial; both the length of time and severity of anoxic conditions are uncertain. Panthalassa Ocean circulation models show varying results, ranging from a well-ventilated deep ocean to rapidly developing northern, but not southern, latitude anoxia in response to Siberian Traps driven global warming. To address this uncertainty we examined a southern paleo-latitude pelagic record. Trace metal and pyrite framboid data show bottom water euxinc conditions developed in the southern Panthalassa Ocean at the PTME, coincident with enhanced volcanic activity indicated by Hg geochemistry. While a global deep-ocean euxinic event at the PTME placed extraordinary stress on marine life, southern surface waters appear to have recovered more quickly as radiolarian populations return several million years before they do in northern Panthalassa.</p>

scholarly journals Transient Permian-Triassic euxinia in the southern Panthalassa deep ocean

Geology ◽  
2021 ◽  
Author(s):  
S.E. Grasby ◽  
D.P.G. Bond ◽  
P.B. Wignall ◽  
R. Yin ◽  
L.J. Strachan ◽  
...  
Keyword(s):  
Global Warming ◽  
Ocean Circulation ◽  
Surface Waters ◽  
Mass Extinction ◽  
Bottom Water ◽  
Deep Ocean ◽  
Global Ocean ◽  
Marine Life ◽  
Siberian Traps ◽  
Southern Latitude

Both the duration and severity of deep-water anoxic conditions across the Permian-Triassic mass extinction (PTME) are controversial. Panthalassa Ocean circulation models yield varying results, ranging from a well-ventilated deep ocean to rapidly developing northern-latitude, but not southern-latitude, anoxia in response to Siberian Traps–driven global warming. To address this uncertainty, we examined a southern-paleolatitude pelagic record. Trace metal and pyrite framboid data suggest bottom-water euxinic conditions developed in the southern Panthalassa Ocean at the PTME, coincident with enhanced volcanic activity indicated by Hg geochemistry. While a global ocean euxinic event at the PTME placed extraordinary stress on marine life, southern surface waters appear to have recovered more quickly as radiolarian populations returned several million years before they did in northern Panthalassa.

scholarly journals Long-term response of oceanic carbon uptake to global warming via physical and biological pumps

2018 ◽  
Vol 15 (13) ◽  
pp. 4163-4180 ◽  
Author(s):  
Akitomo Yamamoto ◽  
Ayako Abe-Ouchi ◽  
Yasuhiro Yamanaka
Keyword(s):  
Global Warming ◽  
Ocean Circulation ◽  
General Circulation ◽  
Deep Ocean ◽  
Biogeochemical Model ◽  
Carbon Uptake ◽  
Co2 Uptake ◽  
Biological Pumps ◽  
Circulation Change ◽  
Oceanic Carbon

Abstract. Global warming is expected to significantly decrease oceanic carbon uptake and therefore increase atmospheric CO2 and global warming. The primary reasons given in previous studies for such changes in the oceanic carbon uptake are the solubility reduction due to seawater warming and changes in the ocean circulation and biological pump. However, the quantitative contributions of different processes to the overall reduction in ocean uptake are still unclear. In this study, we investigated multi-millennium responses of oceanic carbon uptake to global warming and quantified the contributions of the physical and biological pumps to these responses using an atmosphere–ocean general circulation model and a biogeochemical model. We found that global warming reduced oceanic CO2 uptake by 13 % (30 %) in the first 140 years (after 2000 model years), consistent with previous studies. Our sensitivity experiments showed that this reduction is primarily driven by changes in the organic matter cycle via ocean circulation change and solubility change due to seawater warming. These results differ from most previous studies, in which circulation changes and solubility change from seawater warming are the dominant processes. The weakening of biological production and carbon export induced by circulation change and lower nutrient supply, diminishes the vertical DIC gradient and substantially reduces the CO2 uptake. The weaker deep-ocean circulation decreases the downward transport of CO2 from the surface to the deep ocean, leading to a drop in CO2 uptake in high-latitude regions. Conversely, weaker equatorial upwelling reduces the upward transport of natural CO2 and therefore enhances the CO2 uptake in low-latitude regions. Because these effects cancel each other out, circulation change plays only a small direct role in the reduction of CO2 uptake due to global warming but a large indirect role through nutrient transport and biological processes.

scholarly journals Does the sensitivity of Southern Ocean circulation depend upon bathymetric details?

2014 ◽  
Vol 372 (2019) ◽  
pp. 20130050 ◽  
Author(s):  
Andrew McC. Hogg ◽  
David R. Munday
Keyword(s):  
Southern Ocean ◽  
Wind Stress ◽  
Ocean Circulation ◽  
Bottom Water ◽  
Deep Ocean ◽  
Ocean Eddies ◽  
Oceanic Response ◽  
Water Formation ◽  
Circumpolar Current ◽  
Bottom Water Formation

The response of the major ocean currents to changes in wind stress forcing is investigated with a series of idealized, but eddy-permitting, model simulations. Previously, ostensibly similar models have shown considerable variation in the oceanic response to changing wind stress forcing. Here, it is shown that a major reason for these differences in model sensitivity is subtle modification of the idealized bathymetry. The key bathymetric parameter is the extent to which the strong eddy field generated in the circumpolar current can interact with the bottom water formation process. The addition of an embayment, which insulates bottom water formation from meridional eddy fluxes, acts to stabilize the deep ocean density and enhances the sensitivity of the circumpolar current. The degree of interaction between Southern Ocean eddies and Antarctic shelf processes may thereby control the sensitivity of the Southern Ocean to change.

scholarly journals Phytoplankton community disruption caused by latest Cretaceous global warming

2019 ◽  
Author(s):  
Johan Vellekoop ◽  
Lineke Woelders ◽  
Appy Sluijs ◽  
Kenneth G. Miller ◽  
Robert P. Speijer
Keyword(s):  
Global Warming ◽  
New Jersey ◽  
Surface Waters ◽  
Mass Extinction ◽  
Phytoplankton Community ◽  
Sea Surface ◽  
Benthic Ecosystems ◽  
Chicxulub Impact ◽  
Marine Community

Abstract. Phytoplankton responses to a ~ 350 kiloyear long phase of gradual late Maastrichtian (latest-Cretaceous) global warming starting at ~ 66.4 Ma can provide valuable insights into the long-term influences of global change on marine ecosystems. Here we perform micropaleontological analyses on three cores from the New Jersey paleoshelf, to assess the response of phytoplankton using cyst-forming dinoflagellates and benthic ecosystems using benthic foraminifera. Our records show that this Latest Maastrichtian Warming Event (LMWE), characterized by a 4.0 ± 1.3 ⁰C warming of sea-surface waters on the New Jersey paleoshelf, resulted in a succession of nearly monospecific dinoflagellate cyst assemblages, dominated by the species Palynodinium grallator. This response, likely triggered by the combination of warmer and seasonally thermally-stratified seas, appears to have been more intense at offshore sites than at nearshore sites. The LMWE, and related dinoflagellate response, is associated with an impoverished benthic ecosystem. A wider geographic survey of literature data reveals that the dominance of P. grallator is a marker for the LMWE throughout the northern mid-latitudes. While the dinocyst assemblage returned to a stable, normal marine community in the last tens of thousands of years of the Maastrichtian, benthic foraminiferal diversity remained slightly suppressed. Increased ecosystem stress during the latest Maastrichtian potentially primed global ecosystems for the subsequent mass extinction following the K-Pg boundary Chicxulub impact.

scholarly journals Long-term response of oceanic carbon uptake to global warming via physical and biological pumps

2017 ◽  
Author(s):  
Akitomo Yamamoto ◽  
Ayako Abe-Ouchi ◽  
Yasuhiro Yamanaka
Keyword(s):  
Global Warming ◽  
Ocean Circulation ◽  
General Circulation ◽  
Deep Ocean ◽  
Biogeochemical Model ◽  
Carbon Uptake ◽  
Co2 Uptake ◽  
Biological Pump ◽  
Circulation Change ◽  
Oceanic Carbon

Abstract. Global warming is expected to significantly decrease oceanic carbon uptake and therefore accelerate an increase in atmospheric CO2 and global warming. The primary reasons in previous studies for the change in the oceanic carbon uptake are the solubility reduction due to seawater warming and changes in the ocean circulation and biological pump. However, quantifications of the contributions from different processes to the overall reduction in ocean uptake are still unclear. Herein, we investigate multimillennium response of oceanic carbon uptake to global warming and quantify the contributions of the physical and biological pump to the response using an atmosphere–ocean general circulation model and a biogeochemical model. We found that global warming reduced oceanic CO2 uptake by 13 % (30 %) in the first 140 years (at year 2000), which is consistent with previous studies. Sensitivity studies show that changes in the biological pump via ocean circulation change and solubility change due to seawater warming are dominant processes in the uptake reduction. These results are contrary to most previous studies wherein circulation changes and solubility change from seawater warming are the dominant processes. The weakening of biological production and carbon export induced by lower nutrient supply diminishes the vertical gradient of DIC substantially reducing the CO2 uptake. The weaker deep-ocean circulation decreases the downward transport of CO2 from the surface to the deep ocean, leading to a drop in the CO2 uptake in high-latitude regions. Conversely, weaker equatorial upwelling reduces the upward transport of natural CO2 and therefore enhances the CO2 uptake in low-latitude regions. Because these effects cancel each other, the circulation change becomes a second-order process. Our results suggest that the biological pump plays a significant role in the future oceanic carbon uptake through natural carbon cycle.

scholarly journals Phytoplankton community disruption caused by latest Cretaceous global warming

2019 ◽  
Vol 16 (21) ◽  
pp. 4201-4210 ◽  
Author(s):  
Johan Vellekoop ◽  
Lineke Woelders ◽  
Appy Sluijs ◽  
Kenneth G. Miller ◽  
Robert P. Speijer
Keyword(s):  
Global Warming ◽  
New Jersey ◽  
Surface Waters ◽  
Mass Extinction ◽  
Phytoplankton Community ◽  
Sea Surface ◽  
Benthic Ecosystems ◽  
Chicxulub Impact ◽  
Marine Community

Abstract. Phytoplankton responses to a ∼350 kyr (kiloyear) long phase of gradual late Maastrichtian (latest Cretaceous) global warming starting at ∼66.4 Ma can provide valuable insights into the long-term influences of global change on marine ecosystems. Here we perform micropaleontological analyses on three cores from the New Jersey paleoshelf to assess the response of phytoplankton using cyst-forming dinoflagellates and benthic ecosystems using benthic foraminifera. Our records show that this latest Maastrichtian warming event (LMWE), characterized by a 4.0±1.3 ∘C warming of sea surface waters on the New Jersey paleoshelf, resulted in a succession of nearly monospecific dinoflagellate-cyst assemblages, dominated by the species Palynodinium grallator. This response, likely triggered by the combination of warmer and seasonally thermally stratified seas, appears to have been more intense at offshore sites than at nearshore sites. The LMWE, and related dinoflagellate response, is associated with an impoverished benthic ecosystem. A wider geographic survey of literature data reveals that the dominance of P. grallator is a marker for the LMWE throughout the northern midlatitudes. While the dinocyst assemblage returned to a stable, normal marine community in the last tens of thousands of years of the Maastrichtian, benthic foraminiferal diversity appears to have remained slightly suppressed. Increased ecosystem stress during the latest Maastrichtian potentially primed global ecosystems for the subsequent mass extinction following the Cretaceous Paleogene (K–Pg) boundary Chicxulub impact.

scholarly journals Digitalized Earth's most severe sea-level regression and extinction

2021 ◽  
Author(s):  
Mingxing Dong
Keyword(s):  
Global Warming ◽  
Sea Level ◽  
Mass Extinction ◽  
Upper Permian ◽  
Nw China ◽  
Siberian Traps ◽  
The Past ◽  
The World ◽  
Permian Mass Extinction ◽  
Bayan Har

Abstract End-Permian mass extinction is the largest bio-crises in the past 542 million years in Earth's history. Despite half a century of study, what caused the catastrophe remains equivocal. Fossil collections in the study area of Bayan Har, NW China, suggest a continuous Permian sequence, whereas most mid-to-upper Permian strata were missing. By correlating the Permian sequence reconstructed from reworked carbonate clasts with the measured Permian section, we corroborate a sea-level fall of at least 354 m caused by plume-induced uplift, resulted in the erosion of the last 15-Myr Permian carbonate strata, from Uppermost Permian to the fusulinid zone. The marine regression and resultant erosion occurred not only in China but also in Canadian Arctica[1], Oman[2], Canadian Rockies[3], Norway[3], North America[3] all over the world. New sections and digitalized sea-level regression demonstrate that the period of extinction falls within the hiatus, a break in deposition between the uppermost Permian carbonate strata and the clasts reworked from Permian platforms, representing a duration of sea-level drop 354 m. Carbonate clasts, Siberian Traps volcanism, global warming, anoxia, and ocean acidification are all post-extinction geological events. Why did the extinction occur during the falling stage? We will never know because we can't study a hiatus unrepresented by strata unless we associate the extinction with the sea-level drop.

scholarly journals Variations in intermediate and deep ocean circulation in the subtropical northwestern Pacific from 26 ka to present based on a new calibration for Mg/Ca in benthic foraminifera

2014 ◽  
Vol 10 (2) ◽  
pp. 1265-1303 ◽  
Author(s):  
Y. Kubota ◽  
K. Kimoto ◽  
T. Itaki ◽  
Y. Yokoyama ◽  
Y. Miyairi ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Benthic Foraminifera ◽  
North Pacific ◽  
Bottom Water ◽  
Deep Ocean ◽  
Northwestern Pacific ◽  
Okinawa Island ◽  
The North ◽  
Deep Ocean Circulation ◽  
The North Pacific

Abstract. To understand variations in intermediate and deep ocean circulation in the North Pacific, bottom water temperatures (BWT), carbon isotopes (δ13C) of benthic foraminifera, and oxygen isotopes (δ18O) of seawater at a water depth of 1166 m were reconstructed from 26 ka to present. A new regional Mg/Ca calibration for the benthic foraminifera Cibicidoides wuellerstorfi was established to convert the benthic Mg/Ca value to BWT, based on twenty-six surface sediment samples and a core top sample retrieved around Okinawa Island. In addition, core GH08-2004, retrieved from 1166 m water depth east of Okinawa Island, was used to reconstruct water properties from 26 ka to present. During the Last Glacial Maximum (LGM), from 24 to 18 ka, BWT appeared to be relatively constant at approximately 2 °C, which is ~1.5–2 °C lower than today. One of the prominent features of our BWT records was a millennial-scale variation in BWT during the last deglaciation, with BWT higher during Heinrich event 1 (H1; ~17 ka) and the Younger Dryas (YD; ~12 ka) and lower during the Bølling/Allerød (B/A; ~14 ka). The record of seawater δ18O in core GH08-2004 exhibited a rapid increase in association with the rapid warming of BWT at 17 ka, likely due to the reduced precipitation in the North Pacific in response to less moisture transport from the equatorial Atlantic as a result of the collapse of the Atlantic Meridional Overturning Circulation. During the interval from 17 to 15 ka, the bottom water temperature tended to decrease in association with a decrease in the carbon isotope values of C. wuellerstorfi, likely as a result of increased upwelling of the older water mass that was stored in the abyssal Pacific during the glacial time. The timing of the increased upwelling coincided with the deglacial atmospheric CO2 rise initiated at ~17 ka, and suggested that the increased upwelling in the subtropical northwestern Pacific from 17 to 15 ka contributed to the carbon release from the Pacific into the atmosphere.

Anthropogenic modification of the oceans

2011 ◽  
Vol 369 (1938) ◽  
pp. 887-908 ◽  
Author(s):  
Toby Tyrrell
Keyword(s):  
Global Warming ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ocean Circulation ◽  
Human Activities ◽  
Sea Water ◽  
Deep Ocean ◽  
Considerable Reduction ◽  
Surface Ocean ◽  
And Sea Level

Human activities are altering the ocean in many different ways. The surface ocean is warming and, as a result, it is becoming more stratified and sea level is rising. There is no clear evidence yet of a slowing in ocean circulation, although this is predicted for the future. As anthropogenic CO 2 permeates into the ocean, it is making sea water more acidic, to the detriment of surface corals and probably many other calcifiers. Once acidification reaches the deep ocean, it will become more corrosive to CaCO 3 , leading to a considerable reduction in the amount of CaCO 3 accumulating on the deep seafloor. There will be a several thousand-year-long interruption to CaCO 3 sedimentation at many points on the seafloor. A curious feedback in the ocean, carbonate compensation, makes it more likely that global warming and sea-level rise will continue for many millennia after CO 2 emissions cease.

On the impact of sea ice in a global ocean circulation model

1997 ◽  
Vol 25 ◽  
pp. 111-115 ◽  
Author(s):  
Achim Stössel
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Deep Ocean ◽  
Global Ocean ◽  
Convective Activity ◽  
The Impact

This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.

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