Nearly all dinosaurs and about 3/4 of Earth’s plant and animal species were killed about 66 million years ago during a mass extinction event.
The extinction event is associated with the impact of the Chicxulub asteroid near modern-day Merida, Mexico. However, recent research finds there was a global increase in mercury and warming before the extinction event.
The asteroid impact was significant enough to mark a new geologic time period. The Cretaceous–Paleogene (K–Pg) extinction event led to the extinction of three-quarters of plant and animal species on Earth. The asteroid impact caused an “impact winter,” where enough dust and particulates are thrown into the atmosphere that photosynthesis is severely diminished. The near halting of photosynthesis and rapid acidification of the oceans were major factors leading to widespread extinction.
This global increase is associated with the massive volcanic eruptions of the Deccan Traps in western India. The scale of the Deccan Traps eruption is hard to comprehend. The eruption covered 200,000 square miles with lava over a mile thick (6,600 feet). That’s larger than the state of California covered in over a mile thick of lava.
The eruption of the Deccan Traps began before the impact of the Chicxulub asteroid and now with the use of geochemical isotopic analysis on mollusk shells from around the world scientists have pinpointed the eruptions to a global increase in mercury and warming from the release of carbon dioxide.
The research was conducted by a team from the University of Michigan and is scheduled for publication on Dec.16 in the journal Nature Communications.
The team found the first occurrence that ties global warming and mercury increase from the same samples across the globe. The mercury levels were aligned with mercury levels from a present-day mercury pollution site in Virginia’s Shenandoah Valley.
Environmental limits would advise no fishing or eating fish from waters with the equivalent mercury levels that were seen 66 million years ago. On top of that, these mercury levels lasted for up to thousands of years and across the globe.
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