Asteroid impact made the Earth uninhabitable for dinosaurs
A research team from UCL, Imperial College London and the University of Bristol has shown that only the asteroid impact could have created conditions that were unfavourable for dinosaurs across the globe. In the study, they also show that the massive volcanism could also have helped life recover from the asteroid strike in the long term. The asteroid strike would have released particles and gases high into the atmosphere, blocking out the Sun for years and causing permanent winters. Volcanic eruptions also produce particles and gases with Sun-blocking effects, and around the time of the mass extinction there were tens of thousands of years of eruptions at the Deccan Traps, in present-day India.
To determine which factor, the asteroid or the volcanism, had more climate-changing power, researchers have traditionally used geological markers of climate and powerful mathematical models. In the new paper, the team combined these methods with information about what kinds of environmental factors, such as rainfall and temperature, dinosaur species needed to thrive.
They were then able to map where these conditions would still exist in a world after either an asteroid strike or massive volcanism. They found that only the asteroid strike wiped out all potential dinosaur habitats, while volcanism left some viable regions around the equator.
Although volcanoes release Sun-blocking gases and particles, they also release carbon dioxide, a greenhouse gas. In the short term after an eruption, the Sun-blockers have a larger effect, causing a ‘volcanic winter’. However, in the longer term these particles and gases drop out of the atmosphere, while carbon dioxide stays around and builds up, warming the planet. After the initial drastic global winter caused by the asteroid, the team’s model suggests that in the longer term, volcanic warming could have helped restore many habitats, helping new life that evolved after the disaster to thrive.
(Content Courtesy: https://www.ucl.ac.uk/news/2020/jun/asteroid-impact-not-volcanoes-made-earth-uninhabitable-dinosaurs)