Evolution: driven by extinctions: too much phosphorus (Evolution)

by David Turell , Monday, December 06, 2021, 19:29 (1081 days ago) @ David Turell

From volcanic activity:

https://www.sciencedaily.com/releases/2021/12/211202113215.htm

"Scientists have discovered that two intense spells of volcanic activity triggered a period of global cooling and falling oxygen levels in the oceans, which caused one of the most severe mass extinctions in Earth history - the 'Late Ordovician Mass Extinction', 450 million years ago.

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"This period brought about intense planetary cooling, which culminated in a glaciation and the major 'Late Ordovician Mass Extinction'. This extinction led to the loss of about 85% of species dwelling in the oceans, reshaping the course of evolution of life on Earth.

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"The team identified that two exceptionally large pulses of volcanic activity across the globe, occurring in parts of present-day North America and South China, coincided very closely with the two peaks in glaciation and extinction. "But intense bursts of volcanism are more typically linked to massive CO2 release, which should drive global warming, so another process must be responsible for sudden cooling events," explains Dr Gernon.

"This prompted the team to consider whether a secondary process -- natural breakdown or 'weathering' of the volcanic material -- may have provided the surge in phosphorus need to explain the glaciations.

"'When volcanic material is deposited in the oceans it undergoes rapid and profound chemical alteration, including release of phosphorus, effectively fertilizing the oceans," states co-author Professor Martin Palmer from the University of Southampton. "So, it is seemed viable hypothesis and certainly one worth testing."

"This prompted the team to consider whether a secondary process -- natural breakdown or 'weathering' of the volcanic material -- may have provided the surge in phosphorus need to explain the glaciations.

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"'This prompted us to develop a global biogeochemical model to understand the knock-on effects on the carbon cycle of rapidly adding a surge of phosphorus leached from volcanic deposits into the ocean," says Dr Benjamin Mills, Associate Professor at the University of Leeds and co-author on the study.

"The team discovered that widespread blankets of volcanic material laid down on the seafloor during the Ordovician Period would have released sufficient phosphorus into the ocean to drive a chain of events, including climatic cooling, glaciation, widespread reduction in ocean oxygen levels, and mass extinction.

"Whilst it might be tempting to think that seeding the oceans with phosphorus may help solve the current climate crisis, the scientists caution that this may have more damaging consequences. "Excess nutrient runoff from sources like agricultural fertilisers is a major cause of marine eutrophication -- where algae grow rapidly and then decay, consuming oxygen and causing substantial damage to ecosystems at the present day," cautions Dr Mills."

Comment: Life and inorganic systems are intertwined as this study shows. Changes in the amount of living matter can alter the climate and cause extinctions which change the course of evolution. These systems are in a delicate balance, without which we wouldn't be here. The huge bush of life is simply a part of those required systems, something dhw doesn't understand when he asks why God didn't simply produce humans instead of all that really happened.