The turning factors of world warming brought about the Paleocene-Eocene thermal most – watts with that?

Guest contribution by Eric Worrall

According to one study, the Paleocene-Eocene thermal maximum, an extreme increase in global warming 55 million years ago, was not caused solely by volcanism and geological upheaval.

“Tipping points” in the earth system triggered rapid climate change 55 million years ago, as research shows

from University of Exeter

Scientists have gained fascinating new insight into the causes of one of the fastest and most dramatic cases of climate change in Earth’s history.

A research team led by Dr. Sev Kender of the University of Exeter has made a major breakthrough in the cause of the Paleocene-Eocene Thermal Maximum (PETM) – an extreme global warming event that has lasted about 150,000 years in significant temperature increases.

Although previous studies suggested that volcanic activity contributed to the huge CO2 emissions that caused rapid climate change, the trigger for the event is less clear.

In the new study, shortly before and at the start of the PETM, the researchers identified elevated levels of mercury in samples from sediment cores in the North Sea, which could be caused by extensive volcanic activity.

Crucially, examining the rock samples also showed that there was a marked decrease in mercury levels in the early stages of PETM – suggesting that at least one other carbon reservoir was emitting significant greenhouse gases when the phenomenon was occurring.

Research points to the existence of tipping points in the Earth system that could trigger the release of additional carbon stores that could drive Earth’s climate to unprecedented high temperatures.

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The abstract of the study;

Paleocene / Eocene carbon feedback triggered by volcanic activity

Sev Kender, Kara Bogus, Gunver K. Pedersen, Karen Dybkjær, Tamsin A. Mather, Erica Mariani, Andy Ridgwell, James B. Riding, Thomas Wagner, Stephen P. Hesselbo & Melanie J. Leng


The Paleocene-Eocene Thermal Maximum (PETM) was a time of geologically rapid carbon release and global warming ~ 56 million years ago. Although modeling, outcrops, and proxy records suggest that volcanic carbon was released, it has not yet been possible to identify the PETM trigger or whether multiple carbon reservoirs were involved. Here we report increased levels of mercury compared to organic carbon – a proxy for volcanism – just in front of and within the early PETM from two North Sea sediment cores, meaning that pulsed volcanism from the North Atlantic Eruptive Province likely provided the trigger and subsequently increased levels of CO2 maintained. However, the onset of PETM coincides with a mercury low, suggesting that at least one other carbon reservoir has released significant greenhouse gases in response to the initial warming. Our results support the existence of “kipping points” in the earth system, which trigger the release of additional carbon stores and can drive the earth’s climate into a hotter state.

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To be fair, the authors of this study, unlike some studies in the main part of their paper, warn in advance that it is difficult to draw conclusions from events that occurred during the Paleocene-Eocene thermal maximum and that are relevant to modern times.

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