Ancient Fish Thrives During PETM Extreme Global Warming – Huge Fall Because of That?

Guest essay by Eric Worrall

The Paleocene-Eocene Thermal Maximum (PETM), a period of extremely rapid global warming that occurred 10 million years after the extinction of the dinosaurs, is thought to be an ocean disaster. Instead, even mild-climate fish treat the warmth like a tropical buffet.

Ancient fish thrived in times of rapid global warming

Teeth and scales preserved in marine sediments suggest that fish thrived during one of the Earth’s fastest warming periods.

Via Elyse DeFranco December 14, 2021

About 55 million years ago, Earth’s climate experienced a period of rapid and intense warming, both on land and at sea. Temperatures have risen by more than 5°C, and even the seas of the Arctic have turned tropical. Recreate this warm era, Paleocene-Eocene Thermal Maximum (PETM), providing a glimpse into the possible future of the Earth. “One of the best tools we have for understanding how [ocean] the feedback system is to look at past instances of global change,” Elizabeth Sibert, a paleontologist and paleontologist at the Yale Institute for Atmospheric Research.

By examining fossil evidence from PETM preserved in marine sediment cores, Sibert and her colleagues sought to understand how fish might respond to warming oceans. Contrary to the predictions of many models, they found that fish actually proliferated more when the temperature increased. Sibert and her team will present search on December 14 at the AGU Fall 2021 Meeting.

…

Sibert and her team examined sediment records in three different cores collected by Marine drilling program. Drilling sites span the tropics of the north central Pacific, eastern equatorial Pacific and Atlantic oceans. The researchers filtered microscopic fish scales and teeth from different depths of sediment cores, counting and classifying them to get a window into past ocean life in the PETM.

“This is the first time we have an idea of ​​what the mid-to-higher tropics have been doing during this warming event,” said the team member. Richard Norris, a paleontologist at the Scripps Institution of Oceanography. “Previously, most of the PETM studies were based on single-celled plankton or micro-plankton.”

The results paint a consistent picture of the past across all three samples: Fish becomes more abundant as the temperature rises, then decreases again as warming subsides. More, The different types of fish did not change much during this temperature. “It was really surprising,” said Norris. “You would think that when things warmed up, you could get a really different community of fish.”

…

Still, Sibert recommends caution when comparing fish results in PETM and what could happen this century — and beyond. “The rate of warming… can have distinct and dramatic effects on marine ecosystems,” she notes.

…

Read more: https://eos.org/articles/ancient-fish-thrived-during-a-period-of-rapid-global-warming

Summary of the study;

PP23A-02 – Enhanced oceanic fish production and community resilience across Paleocene-Eocene heat peaks

abstract

Elizabeth C Sibert Yale University
Douglas W Tomczik Scripps Institute of Oceanography
Daniel Gaskell Yale University
Gregory L. Britten Massachusetts Institute of Technology
Richard D Norris Scripps Institute of Oceanography

Marine ecosystem models predict that anthropogenic warming will likely lead to reduced marine fish production in the coming centuries, although the magnitude of this effect is very limited. In contrast, early Paleogene research (62-48 Ma) has suggested that periods of warmer climates are associated with long-term increases in high-ocean fish production. The historical response of fish communities to rapid-scale warming events close to anthropogenic warming rates remains unknown. The Paleocene-Eocene Thermal Maximum (PETM) is a transient and rapid period of global warming about 56 million years ago (Ma) and is partially analogous to modern climate change. To examine how fish populations responded to rapid ocean warming in the past, we compiled a profile of fish diversity and abundance on PETM, using microscopic fish teeth and scales. Isolated ichthyoliths are preserved in three deep-sea sediment cores: Site Drilling Program (ODP) Site 1209 in the North Pacific, ODP Site 1220 in the Equatorial Pacific and ODP Site 1260 in the North Equator Atlantic. We see that, Contrary to future projections, ichthyolith accumulation rates (IARs) from all sites showed a significant increase in fish production coinciding with the early stages of PETM, before returning to levels before PETM when hyperthermia conditions weaken. Furthermore, the morphological and compositional diversity of PETM ichthyolith aggregates remained virtually constant throughout the course of the event, with no evidence of excursion or disaster bias. These findings suggest that fish species may be more resilient to global climate change than previously thought. Furthermore, the temperature sensitivity of fish production over the rapid warming of PETM can be quantitatively compared with the temperature sensitivity of fish production during the Early Paleogene, providing a means to evaluate Questioning the sensitivity of fish populations to changes in ocean temperature throughout the Earth’s past and on different time scales.

Read more: https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/934149

Well done to the authors for having the courage to report and present their findings.

I enjoyed being at the AGU meeting where Elizabeth and other authors presented their research, her proof that all models of global warming of the warning biome were carefully designed. Theirs could be completely wrong.