Dinosaur-Killing Meteorite Caused Acidification That Led to Mass Extinction

Fossils from 66 million years ago have pointed to a potential link between mass extinction of marine life and ocean acidification.

A study published yesterday by the National Academy of Sciences revealed how the collapse of marine species occurred following a meteorite’s impact that wiped out the dinosaurs. The meteorite increased carbon levels in the atmosphere and altered the chemistry of the Earth’s oceans over time.

Researchers studied marine animals with shells, known as foraminifera, to determine how a spike in carbon levels increased ocean acidification.

Their findings argued that the disappearance of the organisms occurred after pH levels dropped 0.25 unit between 100 and 1,000 years after the meteorite hit. Acidification then intensified.

One of the study’s authors, Ellen Thomas, a senior research scientist in Yale University’s geology and geophysics department, noted how increased ocean acidity raised the risk for extinction of marine organisms with shells.

“If we have more acidic oceans, then on the one hand, it is more difficult, it takes more energy for organisms to make a calcium carbonate shell,” Thomas said.

As chemical changes occur when salt water reacts with carbon dioxide, the pH level falls and ocean acidity levels rise.

NOAA reported that following the Industrial Revolution, the pH levels in oceans dropped by 0.11 unit. That translates to a 30% hike in acidity levels.

NOAA launched its Ocean Acidification Program in 2011 as part of a larger effort to monitor, research and educate the public on the impacts of the changing chemistry of the oceans.

The program has funded multiple research projects along the Gulf of Mexico, in coral ecosystems and in the Southeast.

Emily Osborne, a University Corporation for Atmospheric Research visiting scientist with the NOAA Ocean Acidification Program, explained how the study’s findings coincided with NOAA’s modern-day research on ocean acidification.

“Model projections suggest that if business-as-usual scenarios continue into the future, we might see pH decline on the scale that was observed in this study as a result of that [meteorite] impact,” Osborne said.

Ocean acidification is reversible, but Thomas pointed out that changes in chemistry cannot be altered for thousands of years.

“They are reversible on time scales that are so long that humans are not really interested in that,” Thomas said. “We’re talking reversible on time scales of 10,000 to 100,000 years.”

Published in conjunction with E&E News and Scientific American

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