Volcanoes to Blame for Largest Global Warming Event in 66 Million Years

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The mysterious cause of the largest natural global warming event in the last 66 million years is no more with research led by the University of Southampton that found volcanoes were to blame and they have been metaphorically caught ‘red handed’.

The Palaeocene-Eocene Thermal Maximum (PETM) was an event in the Earth’s history where the atmospheric CO2 more than doubled in less than 25,000 years, a mere blink of an eye in the geological timeline. The PETM caused the Earth to increase in temperature by 5 degrees due to a sudden injection of CO2 into the atmosphere, it was this injection that had stumped scientists, until now.

By using the world-leading geochemical facilities located at the University of Southampton, scientists investigated the chemical makeup of microscopic shells from tiny marine plankton that lived millions of years ago. This allowed them to calculate the composition of the Earth’s atmosphere around the time of the PETM.

Credit: Gavin Foster

Professor Andy Ridgwell from the University of California summed up the results with:

Ocean pH tells us about the amount of carbon absorbed by ancient seawater, […] the results point to the large-scale volcanism associated with the opening of the North Atlantic as the primary driver of the PETM.

The study, which has been published in Nature, has shown that the PETM coincided with the creation of ‘flood basalts’, the consequence of a series of major eruptions. It was these eruptions which caused more than 12,000 petagrams (12,000,000,000,000 tonnes) of carbon to enter the atmosphere, more than 30 times that of all the fossil fuels that have been burned by human kind. The Earth’s mantle has more than enough carbon to be able to release such amounts, and this final link of volcanic eruptions has provided the mechanism of how this carbon was transferred from the magma into the air.

It’s worth noting that these sort of studies have very real applications to modern day investigations into climate change.

Dr Philip Sexton from the Open University commented:

…one unexpected result of our study was that enhanced organic matter burial was important in ultimately drawing down the released carbon out of the atmosphere and ocean and thereby accelerating the recovery of the Earth system. This shows the value of studying these ancient warming events as they provide really valuable insights into how Earth behaves when its climate system and carbon cycle are dramatically perturbed.”

With this final comment being vital, this study could help pave the way for a solution for our Earth in regards to modern day climate change. However, with today’s human-made carbon emissions occurring at 20 times the rate of that in the PETM, time is already starting to run out…

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