The University of Sydney, Australia (May 2022) - How plate tectonics has maintained Earth's 'Goldilocks' climate

Title:

How plate tectonics has maintained Earth's 'Goldilocks' climate 

 

Published:

The University of Sydney, 26 May 2022

https://www.sydney.edu.au/news-opinion/news/2022/05/26/how-plate-tectonics-have-maintained-earth-s--goldilocks--climate.html

 

From the article:

Not hothouse, nor icehouse: when tectonic plates move at a moderate speed - not too fast or slow - Earth remains habitable, new University of Sydney research finds.

 

ALSO SEE

 

Müller, R.D., Mather, B., Dutkiewicz, A. et al. Evolution of Earth’s tectonic carbon conveyor belt. Nature 605, 629–639 (2022). https://doi.org/10.1038/s41586-022-04420-x

Abstract:

Concealed deep beneath the oceans is a carbon conveyor belt, propelled by plate tectonics. Our understanding of its modern functioning is underpinned by direct observations, but its variability through time has been poorly quantified. Here we reconstruct oceanic plate carbon reservoirs and track the fate of subducted carbon using thermodynamic modelling. In the Mesozoic era, 250 to 66 million years ago, plate tectonic processes had a pivotal role in driving climate change. Triassic–Jurassic period cooling correlates with a reduction in solid Earth outgassing, whereas Cretaceous period greenhouse conditions can be linked to a doubling in outgassing, driven by high-speed plate tectonics. The associated ‘carbon subduction superflux’ into the subcontinental mantle may have sparked North American diamond formation. In the Cenozoic era, continental collisions slowed seafloor spreading, reducing tectonically driven outgassing, while deep-sea carbonate sediments emerged as the Earth’s largest carbon sink. Subduction and devolatilization of this reservoir beneath volcanic arcs led to a Cenozoic increase in carbon outgassing, surpassing mid-ocean ridges as the dominant source of carbon emissions 20 million years ago. An increase in solid Earth carbon emissions during Cenozoic cooling requires an increase in continental silicate weathering flux to draw down atmospheric carbon dioxide, challenging previous views and providing boundary conditions for future carbon cycle models.

Catastrophic Trigger That Led to Earth's Largest Mass Extinction Revealed in Fossils

Title:

Catastrophic Trigger That Led to Earth's Largest Mass Extinction Revealed in Fossils

 

Author:

David Nield

 

Published:

Science Alert, 21 October 2020

https://www.sciencealert.com/scientists-find-the-geochemical-trigger-for-the-world-s-largest-ever-mass-extinction

 

From the article:

Scientists think they've finally come closer to identifying the cause of Earth's worst mass extinction, by tracking down the geochemical trigger that may have started it all.  Known as the Great Dying, the Permian-Triassic extinction event happened around 252 million years ago. The new research is based on a study of fossil shells left behind by clam-like brachiopods in what today is the Southern Alps.

Note from blog owner:

The research was published in a scholarly publication.

Title:

Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations

Authors:

Hana Jurikova, Marcus Gutjahr, Klaus Wallmann, Sascha Flögel, Volker Liebetrau, Renato Posenato, Lucia Angiolini, Claudio Garbelli, Uwe Brand, Michael Wiedenbeck & Anton Eisenhauer 

Published:

Nature Geoscience, 19 October 2020

https://www.nature.com/articles/s41561-020-00646-4

Abstract:

The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. Combined with carbon isotope data, our results are integrated in a geochemical model that resolves the carbon cycle dynamics as well as the ocean redox conditions and nitrogen isotope turnover. We find that the initial ocean acidification was intimately linked to a large pulse of carbon degassing from the Siberian sill intrusions. We unravel the consequences of the greenhouse effect on the marine environment, and show how elevated sea surface temperatures, export production and nutrient input driven by increased rates of chemical weathering gave rise to widespread deoxygenation and sporadic sulfide poisoning of the oceans in the earliest Triassic. Our findings enable us to assemble a consistent biogeochemical reconstruction of the mechanisms that resulted in the largest Phanerozoic mass extinction.