An analysis of prehistoric fossil shells in the Antarctic is lending further credence to a scientific theory that suggests a mass dinosaur extinction 66 million years ago is linked to a 鈥渙ne-two punch鈥� of climate change and an asteroid impact.
Two University of Michigan researchers and a colleague from the University of Florida were able to decipher the Antarctic ocean temperatures from the time period when the dinosaurs disappeared.
They found two 鈥渁brupt鈥� warming surges that coincide with previously documented extinction periods near the end of the Cretaceous Period.
The 鈥渕ass extinction鈥� that occurred between the end of the Cretaceous Period and the start of the Paleogene Period annihilated non-avian dinosaurs and approximately three-quarters of Earth鈥檚 plant and animal species.
While there are multiple theories on what led to the mass extinction of that time period, the new record of prehistoric Antarctic ocean temperatures provides 鈥渟trong support鈥� for the 鈥減ress-pulse extinction mechanism,鈥� which suggests that the 鈥減ress鈥� of the climate change prompted by massive volcanic action in India, followed by a 鈥渃atastrophic pulse鈥� of the asteroid impact on the Yucatan Peninsula in Mexico was to blame.
鈥淭his new temperature record provides a direct link between the volcanism and impact events and the extinction pulses 鈥� that link being climate change,鈥� said Sierra Petersen, a postdoctoral researcher in the University of Michigan鈥檚 environmental sciences department.
After analyzing 鈥�29 remarkably well-preserved鈥� fossil shells collected from Seymour Island in the Antarctic, the researchers were able to determine the temperature of the water they were living in. They found that ocean temperatures in the Antarctic jumped approximately 8 degrees Celcius due to carbon dioxide released in the volcanic eruption.
The sudden and large surge in temperature caused "huge stress" on marine and terrestrial ecosystems, said Andrea Dutton, a professor of geological studies at the University of Florida, who co-authored the report. The second, smaller spike about 150,000 years later "really wiped things out," she told CTV News Channel.
鈥淪o it was this one-two punch between these two things rather than just one thing that caused the mass extinction.鈥�
The devastating effects of the rise in temperature were more severe at higher latitudes, a phenomenon known as polar amplification.
鈥淭his has a lesson for us as we carry into the future that these climate change impacts may be felt to a greater degree at high latitudes.鈥�
The research team did not set out to change the minds of climate change deniers, said Dutton.
鈥淏ut it鈥檚 another piece of the puzzle. It鈥檚 an exciting piece of evidence that we hope will offer a lot of pause for thought.鈥�
The researchers' paper was published in the journal Nature Communications and is titled 鈥淓nd-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change.鈥�
