scholarly journals Salinity changes and anoxia resulting from enhanced runoff during the late Permian global warming and mass extinction event

2017 ◽  
Author(s):  
Elsbeth E. van Soelen ◽  
Richard J. Twitchett ◽  
Wolfram M. Kürschner
Keyword(s):  
Global Warming ◽  
Soil Erosion ◽  
Environmental Changes ◽  
Sea Water ◽  
Hydrological Cycle ◽  
Terrestrial Ecosystem ◽  
Late Permian ◽  
Terrestrial Environment ◽  
Shallow Marine ◽  
Extinction Event

Abstract. The Late Permian biotic crisis had a major impact on marine and terrestrial environments. Rising CO2 levels following Siberian Trap volcanic activity were likely responsible for expanding marine anoxia and elevated water temperatures. This study focusses on one of the stratigraphically most expanded Permian-Triassic records known, from Jameson land, east Greenland. High resolution sampling allows for a detailed reconstruction of the changing environmental conditions during the extinction event and the development of anoxic water conditions. Since very little is known about how salinity was affected during the extinction event, we especially focus on the aquatic palynomorphs and infer changes in salinity from changes in the assemblage and morphology. The extinction event, here defined by a peak in spore/pollen, indicating disturbance and vegetation destruction in the terrestrial environment, postdates a negative excursion in the total organic carbon, but predates the development of anoxia in the basin. Based on the newest estimations for sedimentation rates, the marine and terrestrial ecosystem collapse took between 1.6 to 8 kyrs, a much shorter interval than previously estimated. The palynofacies and palynomorph records show that the environmental changes can be explained by enhanced runoff, increased primary productivity and water column stratification. A lowering in salinity is supported by changes in the acritarch morphology. The length of the processes of the acritarchs becomes shorter during the extinction event and we propose that these changes are evidence for a reduction in salinity in the shallow marine setting of the study site. This inference is supported by changes in acritarch distribution, which suggest a change in palaeoenvironment from open marine conditions before the start of the extinction event to more near-shore conditions during and after the crisis. In a period of sea-level rise, such a reduction in salinity can only be explained by increased runoff. High amounts of both terrestrial and marine organic fragments in the first anoxic layers suggest that high runoff, increased nutrient availability, possibly in combination with soil erosion, are responsible for the development of anoxia in the basin. Enhanced runoff could result from changes in the hydrological cycle during the late Permian extinction event, which is a likely consequence of global warming. In addition, vegetation destruction and soil erosion may also have resulted in enhanced runoff. Salinity stratification could potentially explain the development of anoxia in other shallow marine sites. The input of fresh water and related changes in coastal salinity could also have implications for the interpretation of oxygen isotope records and sea water temperature reconstructions in some sites.

scholarly journals Salinity changes and anoxia resulting from enhanced run-off during the late Permian global warming and mass extinction event

2018 ◽  
Vol 14 (4) ◽  
pp. 441-453 ◽  
Author(s):  
Elsbeth E. van Soelen ◽  
Richard J. Twitchett ◽  
Wolfram M. Kürschner
Keyword(s):  
Global Warming ◽  
Soil Erosion ◽  
Environmental Changes ◽  
Hydrological Cycle ◽  
Seawater Temperature ◽  
Late Permian ◽  
Terrestrial Environment ◽  
Shallow Marine ◽  
Run Off ◽  
Extinction Event

Abstract. The late Permian biotic crisis had a major impact on marine and terrestrial environments. Rising CO2 levels following Siberian Trap volcanic activity were likely responsible for expanding marine anoxia and elevated water temperatures. This study focuses on one of the stratigraphically most expanded Permian–Triassic records known, from Jameson Land, East Greenland. High-resolution sampling allows for a detailed reconstruction of the changing environmental conditions during the extinction event and the development of anoxic water conditions. Since very little is known about how salinity was affected during the extinction event, we especially focus on the aquatic palynomorphs and infer changes in salinity from changes in the assemblage and morphology. The start of the extinction event, here defined by a peak in spore : pollen, indicating disturbance and vegetation destruction in the terrestrial environment, postdates a negative excursion in the total organic carbon, but predates the development of anoxia in the basin. Based on the newest estimations for sedimentation rates, the marine and terrestrial ecosystem collapse took between 1.6 and 8 kyr, a much shorter interval than previously estimated. The palynofacies and palynomorph records show that the environmental changes can be explained by enhanced run-off and increased primary productivity and water column stratification. A lowering in salinity is supported by changes in the acritarch morphology. The length of the processes of the acritarchs becomes shorter during the extinction event and we propose that these changes are evidence for a reduction in salinity in the shallow marine setting of the study site. This inference is supported by changes in acritarch distribution, which suggest a change in palaeoenvironment from open marine conditions before the start of the extinction event to more nearshore conditions during and after the crisis. In a period of sea-level rise, such a reduction in salinity can only be explained by increased run-off. High amounts of both terrestrial and marine organic fragments in the first anoxic layers suggest that high run-off, increased nutrient availability, possibly in combination with soil erosion, are responsible for the development of anoxia in the basin. Enhanced run-off could result from changes in the hydrological cycle during the late Permian extinction event, which is a likely consequence of global warming. In addition, vegetation destruction and soil erosion may also have resulted in enhanced run-off. Salinity stratification could potentially explain the development of anoxia in other shallow marine sites. The input of freshwater and related changes in coastal salinity could also have implications for the interpretation of oxygen isotope records and seawater temperature reconstructions at some sites.

Stratigraphic and sedimentological aspects of the worldwide distribution of Apectodinium in Paleocene/Eocene Thermal Maximum deposits

2021 ◽  
pp. SP511-2020-46
Author(s):  
Christopher N. Denison
Keyword(s):  
Global Warming ◽  
Sea Level ◽  
Environmental Changes ◽  
Calcareous Nannofossil ◽  
Shallow Marine ◽  
Worldwide Distribution ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Taxonomic Changes ◽  
Data Gap

AbstractThe Paleocene/Eocene Thermal Maximum (PETM) is characterized by pronounced global warming and associated environmental changes. In the more-or-less two decades since prior regional syntheses of Apectodinium distribution at the PETM, extensive biological and geochemical datasets have elucidated the effect of rising world temperatures on climate and the biome. A Carbon Isotope Excursion (CIE) that marks the Paleocene/Eocene Boundary (PEB) is associated with an acme of marine dinocysts of the genus Apectodinium in many locations. Distinctive foraminiferal and calcareous nannofossil populations may also be present.For this up-dated, dinocyst-oriented view of the PETM, data from worldwide locations have been evaluated with an emphasis on stratigraphic and sedimentological context. What has emerged is that a change in lithology is common, often to a distinctive siltstone or claystone unit, which contrasts with underlying and overlying lithotypes. This change, present in shallow marine/coastal settings and in deepwater turbidite deposits, is attributed to radical modifications of precipitation and erosional processes. An abrupt boundary carries the implication that some time (of unknowable duration) is potentially missing, which then requires caution in the interpretation of the pacing of events in relation to that boundary. In most instances an ‘abrupt’ or ‘rapid’ CIE onset can be attributed to a data gap at a hiatus, particularly in shallow shelf settings where transgression resulted from sea-level rise associated with the PETM. Truly gradational lower boundaries of the PETM interval are quite unusual, and if present, are poorly known so far. Gradational upper boundaries are more common, but erosional upper boundaries have been reported.Taxonomic changes have been made to clarify identification issues that have adversely impacted some biostratigraphic interpretations. Apectodinium hyperacanthum has been retained in Wetzeliella, its original genus. The majority of specimens previously assigned to Apectodinium hyperacanthum or Wetzeliella (Apectodinium) hyperacanthum have been re-assigned to an informal species, Apectodinium sp. 1. Dracodinium astra has been retained in its original genus as Wetzeliella astra, and is emended.

Water and Food in Developing Countries in the Next Century

1998 ◽  
Author(s):  
M. Yudelman
Keyword(s):  
Global Warming ◽  
Fresh Water ◽  
Sea Water ◽  
Hydrological Cycle ◽  
Saline Water ◽  
Weight Of Evidence ◽  
Agricultural System ◽  
Polar Regions ◽  
The Difference ◽  
The Persian Gulf

The world’s supply of water is fixed. It is estimated that 97% of the world’s water exists in the oceans, 2.2% exists as ice and snow, mostly in the polar regions, and only about 0.7% of the total supply is the freshwater that sustains mankind, including the global agricultural system. This quantity of freshwater — around 40,500 km3 — which is the difference between precipitation and evapotranspiration, is continuously replenished by nature’s hydrological cycle. Most climatologists and hydrologists agree that there is no natural process short of climate change, especially global warming, that can increase the world’s rainfall and so the supply of freshwater. The greater the warming, the larger the expected increase in precipitation. One “simple level of analysis” suggests that global warming of 30° C could well lead to a 10% increase in evaporation and an average increase in precipitation of 10%. The biggest increases would be at high latitudes, smaller increases would occur close to the equator (Gleick, 1992). The weight of evidence suggests that this is unlikely to happen within the next several decades (Rosenzweig, 1994). It is an open question, though, as to what might happen in the second half of the next century. There are some manmade processes that can increase the supply of fresh water. One of the most important of these is the conversion of saline water from the ocean into fresh water by removing salt through desalinization or by filtration. Thus far, however, the processes that have been developed are highly energy intensive and costly; the plants presently in operation are mostly in the oil-rich, water-poor nations of the Persian Gulf. It is estimated that there are more than 11,000 desalting plants operating worldwide, but together they produce less than 0.2% of the world’s total fresh water (Postel, 1991). The costs of desalting sea water range currently from about $0.80 to $1.60 m-3, and costs of treating brackish water are about $0.30 m -3, well above the costs of fresh water used for irrigation (Wolf, 1996).

scholarly journals Regions of intensification of extreme snowfall under future warming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lennart Quante ◽  
Sven N. Willner ◽  
Robin Middelanis ◽  
Anders Levermann
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Observational Data ◽  
Climate Models ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Models ◽  
Average Intensity ◽  
High Latitudes ◽  
Future Warming

AbstractDue to climate change the frequency and character of precipitation are changing as the hydrological cycle intensifies. With regards to snowfall, global warming has two opposing influences; increasing humidity enables intense snowfall, whereas higher temperatures decrease the likelihood of snowfall. Here we show an intensification of extreme snowfall across large areas of the Northern Hemisphere under future warming. This is robust across an ensemble of global climate models when they are bias-corrected with observational data. While mean daily snowfall decreases, both the 99th and the 99.9th percentiles of daily snowfall increase in many regions in the next decades, especially for Northern America and Asia. Additionally, the average intensity of snowfall events exceeding these percentiles as experienced historically increases in many regions. This is likely to pose a challenge to municipalities in mid to high latitudes. Overall, extreme snowfall events are likely to become an increasingly important impact of climate change in the next decades, even if they will become rarer, but not necessarily less intense, in the second half of the century.

Diatoms in Saline Lakes Paleoclimate and Paleoecology Interpretations

2007 ◽  
Vol 13 ◽  
pp. 149-168 ◽  
Author(s):  
Erik J. Ekdahl
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Global Climate Change ◽  
Water Conservation ◽  
Environmental Changes ◽  
Global Climate ◽  
Light Availability ◽  
Ionic Concentration ◽  
Mitigation Strategies ◽  
Environmental Response

Average global temperatures are predicted to rise over the next century and changes in precipitation, humidity, and drought frequency will likely accompany this global warming. Understanding associated changes in continental precipitation and temperature patterns in response to global change is an important component of long-range environmental planning. For example, agricultural management plans that account for decreased precipitation over time will be less susceptible to the effects of drought through implementation of water conservation techniques.A detailed understanding of environmental response to past climate change is key to understanding environmental changes associated with global climate change. To this end, diatoms are sensitive to a variety of limnologic parameters, including nutrient concentration, light availability, and the ionic concentration and composition of the waters that they live in (e.g. salinity). Diatoms from numerous environments have been used to reconstruct paleosalinity levels, which in turn have been used as a proxy records for regional and local paleoprecipitation. Long-term records of salinity or paleoprecipitation are valuable in reconstructing Quaternary paleoclimate, and are important in terms of developing mitigation strategies for future global climate change. High-resolution paleoclimate records are also important in groundtruthing global climate simulations, especially in regions where the consequences of global warming may be severe.

Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes

2021 ◽  
Author(s):  
Arbia Jouini
Keyword(s):  
Mass Extinction ◽  
Environmental Changes ◽  
Sea Water ◽  
Sulfur Isotopes ◽  
Deep Understanding ◽  
Sulfur Cycle ◽  
Mass Extinctions ◽  
Deccan Volcanism ◽  
Organic Carbon Burial ◽  
Early Paleocene

<p><strong>Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes</strong></p><p> </p><p>Arbia JOUINI<sup>1*</sup>, Guillaume PARIS<sup>1</sup>, Guillaume CARO<sup>1</sup>, Annachiara BARTOLINI<sup>2</sup></p><p><sup>1 </sup>Centre de Recherches Pétrographiques et Géochimiques, CRPG-CNRS, UMR7358, ,15 rue Notre Dame des Pauvres, BP20, 54501Vandoeuvre-lès-Nancy, France, email:[email protected]</p><p><sup>2</sup> Muséum National D’Histoire Naturelle, Département Origines & Evolution, CR2P MNHN, CNRS, Sorbonne Université, 8 rue Buffon CP38, 75005 Paris, France</p><p> </p><p>The Cretaceous–Paleogene (KPg) mass extinction event 66 million years ago witnessed one of the ‘Big Five’ mass extinctions of the Phanerozoic. Two major catastrophic events, the Chicxulub asteroid impact and the Deccan trap eruptions, were involved in complex climatic and environmental changes that culminated in the mass extinction including oceanic biogenic carbonate crisis, sea water chemistry and ocean oxygen level changes. Deep understanding of the coeval sulfur biogeochemical cycle may help to better constrain and quantify these parameters.</p><p>Here we present the first stratigraphic high resolution isotopic compositions of carbonate associated sulfate (CAS) based on monospecific planktic and benthic foraminifers' samples during the Maastrichtian-Danian transition from IODP pacific site 1209C. Primary δ34SCAS data suggests that there was a major perturbation of sulfur cycle around the KPg transition with rapid fluctuations (100-200kyr) of about 2-4‰ (±0.54‰, 2SD) during the late Maastrichtian followed by a negative excursion in δ34SCAS of 2-3‰ during the early Paleocene.</p><p>An increase in oxygen levels associated with a decline in organic carbon burial, related to a collapse in primary productivity, may have led to the early Paleocene δ34SCAS negative shift via a significant drop in microbial sulfate reduction. Alternatively, Deccan volcanism could also have played a role and impacted the sulfur cycle via direct input of isotopically light sulfur to the ocean. A revised correlation between δ34SCAS data reported in this study and a precise dating of the Deccan volcanism phases would allow us to explore this hypothesis.</p><p>Keywords : KPg boundary, Sulphur cycle, cycle du calcium, Planktic and benthic foraminifera</p><p> </p>

Sign in / Sign up

Export Citation Format

Share Document