Volcanic deposits both on land and on the seafloor are rapidly weathered, launching nutrients like phosphorus to the oceans (example revealed here is Montserrat, West Indies). Credit: Dr. Tom Gernon/University of Southampton
” Its been suggested that international cooling was driven by a boost in phosphorus input to the oceans,” states Dr. Jack Longman, lead author of the research study based at the University of Oldenburg, and previously a postdoctoral researcher at Southampton. “Phosphorus is among the crucial aspects of life, determining the rate at which tiny aquatic organisms like algae can use photosynthesis to convert co2 (CO2) into raw material.” These organisms eventually settle to the seabed and are buried, ultimately lowering levels of carbon dioxide in the environment, which then triggers cooling.
” The unresolved puzzle is why glaciation and extinction took place in 2 unique stages at this time, separated by about 10 million years,” states Dr. Tom Gernon, Associate Professor at the University of Southampton and co-author of the study. “That needs some system to pulse the supply of phosphorus, which is hard to explain.”
The team recognized that two extremely big pulses of volcanic activity around the world, taking place in parts of present-day North America and South China, corresponded very closely with the two peaks in glaciation and termination. “But intense bursts of volcanism are more generally linked to massive CO2 release, which should drive global warming, so another procedure must be accountable for sudden cooling events,” describes Dr. Gernon.
This triggered the team to think about whether a secondary process– natural breakdown or weathering of the volcanic material– may have supplied the rise in phosphorus needed to describe the glaciations.
Abrupt environment modification at the end of the Ordovician Period (~ 450-440 million years ago) triggered the 2nd largest mass termination in Earth history, including the demise of the trilobite, Selenopeltis (visualized, in Oxford University Museum of Natural History). Credit: Dr. Tom Gernon/University of Southampton
” When volcanic product is transferred in the oceans it undergoes extensive and quick chemical modification, including release of phosphorus, effectively fertilizing the oceans,” states co-author Professor Martin Palmer from the University of Southampton. “So, it is seemed practical hypothesis and definitely one worth testing.”
” This led our team to study ashes layers in much more youthful marine sediments to compare their phosphorus contents before and after they were modified by interactions with seawater,” said Dr. Hayley Manners, a lecturer in Organic Chemistry at the University of Plymouth. Geared up with this information, the team was much better positioned to understand the potential geochemical impact of comprehensive volcanic layers from massive eruptions throughout the Ordovician.
” This triggered us to establish a worldwide biogeochemical model to comprehend the ripple effects on the carbon cycle of quickly adding a rise of phosphorus leached from volcanic deposits into the ocean,” states Dr. Benjamin Mills, Associate Professor at the University of Leeds and co-author on the research study.
The team discovered that extensive blankets of volcanic material set on the seafloor throughout the Ordovician Period would have released sufficient phosphorus into the ocean to drive a chain of events, including climatic cooling, glaciation, extensive decrease in ocean oxygen levels, and mass termination.
Whilst it might be appealing to believe that seeding the oceans with phosphorus might help resolve the present environment crisis, the scientists caution that this may have more destructive consequences. “Excess nutrient overflow from sources like farming fertilizers is a major reason for marine eutrophication– where algae grow rapidly and after that decay, consuming oxygen and triggering substantial damage to ecosystems at today day,” warns Dr. Mills.
The scientists conclude that whilst on short timescales enormous volcanic eruptions can warm the environment by means of CO2 emissions, equally they can drive global cooling on multimillion-year timescales. “Our study may trigger reinvestigations of other mass terminations throughout Earth history,” concludes Dr. Longman.
Reference: “Late Ordovician environment change and extinctions driven by elevated volcanic nutrient supply” 2 December 2021, Nature Geoscience.DOI: 10.1038/ s41561-021-00855-5.
Volcanic deposits both on land and on the seafloor are quickly weathered, launching nutrients like phosphorus to the oceans (example revealed here is Montserrat, West Indies). Credit: Dr. Tom Gernon/University of Southampton
Scientists at the University of Southampton have discovered that two extreme durations of volcanism set off a duration of worldwide cooling and falling oxygen levels in the oceans, which triggered among the most extreme mass terminations in Earth history.
The scientists, working with colleagues at the University of Oldenburg, the University of Leeds, and the University of Plymouth, studied the effects of volcanic ash and lava on ocean chemistry throughout a period of severe ecological modification around 450 million years ago. Their findings are published in the journal Nature Geoscience.
This period caused extreme planetary cooling, which culminated in a glaciation and the significant Late Ordovician Mass Extinction. This termination led to the loss of about 85% of species residence in the oceans, improving the course of advancement of life on Earth.