The reign of dinosaurs could have possibly continued if the asteroid that crashed into Earth 66 million years ago had hit the planet elsewhere and not into the Yucatán Peninsula in Mexico, a new study has suggested.
The study, authored by Kunio Kaiho and Naga Oshima, was published in the journal Scientific Reports on Nov. 9. The researchers, from Japan’s Tohoku University in Sendai and the Meteorological Research Institute in Tsukuba, calculated that the asteroid had little more than a one-in-10 chance of triggering a mass extinction when it collided with Earth.
The collision, which resulted in the formation of the Chicxulub crater and wiped out close to 75 percent of animal life on Earth in what is known as the Cretaceous-Paleogene or K-Pg extinction event, was an exceptionally unlikely shot.
If the asteroid had crashed into any other part of the planet, like in the middle of most continents or the ocean, the giant reptiles could have survived annihilation. Only 13 percent of the planet’s surface had the necessary ingredients to turn the asteroid collision into a mass extinction event, according to the study.
Scientists, in general, estimate that the asteroid strike would have released energy a billion times more than the combined power of the atom bombs that destructed Hiroshima and Nagasaki in 1945.
The massive energy produced during the collision had a combustible impact on the huge reservoirs of hydrocarbons and crude oil stored beneath a shallow sea in the Yucatán Peninsula, the authors said.
The combustion would have churned out ample amounts of soot and sulfur into the stratosphere to blot out the sun, triggering a chain of events that would collapse entire ecosystems and destroy three-quarters of Earth’s inhabitants.
Conditions For Mass Extinction
The researchers used global climate model calculations to simulate the amount of soot that asteroid impacts would have generated depending on the amount of hydrocarbon and sulfur in rocks. They also estimated how these different impact scenarios would affect climate.
According to their study, to cause a mass extinction there should be a 10–16 °C drop in global mean surface air temperature on land, an 8–10 °C cooling in the global mean surface air temperature, and the ejection of 1,500 teragrams of soot, which corresponds to 350 teragrams (350 million metric tons) of soot in the stratosphere. This much soot can easily fill 150 fully roofed baseball arenas.
The researchers' impact simulations showed that when the asteroid hit areas high in hydrocarbon, the impact generated enough soot and cooled the planet enough to cause mass extinction.
A 'Rare Case'
"The Chicxulub impact occurred in a hydrocarbon-rich, sulfate-dominated area," the researchers confirmed, adding that is "a rare case of mass extinction being caused at such an impact site." How is this so?
The scientists said that 87 percent of Earth’s surface - areas like most of present-day Africa, China, India, and the Amazon - would not have had high-enough concentrations of hydrocarbons to have such a fateful impact on dinosaurs if the asteroid had collided there.
If, however, the asteroid had crashed into marine coastal areas rich in algae, such as the present-day eastern coast of North America, the Middle East, and Siberia, then the collision would have had the same effect on dinosaurs as the one that created the Chicxulub crater.
Currently, the researchers are also studying the level of climate change that could have been caused by huge volcanic eruptions, which would have had a bearing on other mass extinctions. Consequently, the research will help the team understand the process behind those extinction events.