Volcanic eruptions did not lead to the extinction of the dinosaurs, suggests a new study demonstrating that Earth’s oceans are capable of absorbing large amounts of carbon dioxide—provided it is released gradually over an extremely long time.
Scientists have long argued over the cause of the Cretaceous-Palaeogene extinction event, during which three-quarters of all plant and animal species, including the dinosaurs, went extinct roughly 65 million years ago.
Scientists at Yale and in the United Kingdom say they may have a more definitive answer.
“One way that has been suggested that volcanism could have caused extinction is by ocean acidification, where the ocean absorbs CO2 and becomes more acidic as a result, just as it is doing today with fossil fuel-derived CO2,” said Michael Henehan, a postdoctoral associate at Yale and lead author of a study appearing April 25 in the journal Philosophical Transactions of the Royal Society B.
Most researchers favor the idea that a catastrophic, sudden mechanism such as an asteroid hit triggered the mass die-off, while others say a gradual rise in CO2 emissions from volcanoes in what is now India may have been the cause.
“What we wanted to do was gather all the evidence that’s been collected from ocean sediments from this time and add a few new records of our own, and consider what evidence there is for ocean acidification at this time,” Henehan said.
Henehan and his colleagues analyzed sediments from the deep sea, looking for signs of dissolution that would indicate more acidic oceans. The researchers found that the onset of volcanism did cause a brief ocean acidification event. Critically, though, the pH drop caused by CO2 release was effectively neutralized well before the mass extinction event.
“Combining this with temperature observations that others have made about this time, we think there is a conclusive case that although Deccan volcanism caused a short-lived global warming event and some ocean acidification, the effects were cancelled out by natural carbon cycling processes long before the mass extinction that killed the dinosaurs,” Henehan said.
The study also has implications for understanding modern climate change, the researchers noted. They said it adds to an increasing body of work that suggests restricting CO2 release to much slower and lower levels over thousands of years can allow the oceans to adapt and avoid the worst possible consequences of ocean acidification.
“However, if you cause big disturbances over rapid timescales, closer to the timescales of current human, post-industrial CO2 release, you can produce not only big changes in oceanic ecosystems, but also profound and long-lasting changes in the way the ocean stores and regulates CO2,” Henehan said.
The researchers said their work also suggests that disruption of marine ecosystems can have profound effects on Earth’s climate.
“The direct effects of an asteroid impact, like massive tsunamis or widespread fires, would have lasted only for a relatively short time,” said co-author Donald Penman, a postdoctoral associate at Yale.
‘C’ Division League Football tournament set for February
KATHMANDU— The Martyrs Memorial ‘C’ Division League Football Championship is set to take place in the third week of February 2019.
On Thursday the meeting held between the representatives of All Nepal Football Association (ANFA) and ‘C’ Division clubs at ANFA Complex in Satdobato, Lalitpur set the date for the tournament, shared ANFA Spokesperson Kiran Rai.
League Director Sanjeeb Mishra said, “The ANFA and Club’s representatives have agreed to conduct the competition in the final week of February (second week of Falgun). We will finalize the specific date for the tournament in near future”.
Eleven ‘C’ Division clubs will take part in the Division League.Follow @gorkhapost