He created a map of what the world looked like 66 million years ago and used present day measurements of sedimentary rocks and organic compounds to estimate the global distribution of hydrocarbons during that time.
Dr. Kaiho’s co-author Naga Oshima, a senior researcher at the Meteorological Research Institute in Japan, created a model that simulated asteroid impacts that ejected varying amounts of trapped soot from rock. Only areas with the highest amounts of hydrocarbons released enough soot into the stratosphere to cool the climate to catastrophic levels.
Eighty-seven percent of Earth’s surface, places like most of present day India, China, the Amazon and Africa, would not have had high enough concentrations of hydrocarbons to seal the dinosaurs’ fate. But if the asteroid had hit marine coastal areas thriving with algae, which would have included present day Siberia, the Middle East and the eastern coast of North America, the bang would have been about as devastating to the dinosaurs and life on Earth as the Chicxulub impact.
Scientists not involved with the paper criticized the underlying research.
“The idea that location, location, location is important for an impact, I think is absolutely correct,” said Sean P.S. Gulick, a marine geophysicist from the University of Texas at Austin. But he questioned the authors’ assumptions on where the soot came from and how it affected the climate.
Scientists agree that the planet was blanketed by soot after the impact, but they argue over how it got there. Dr. Gulick said the asteroid impact most likely hurled fiery debris into the sky, which then rained down and ignited firestorms around the world within hours of the crash. The wildfires, he contends, not the burning fossil fuels at the impact site, were what released immense amounts of soot into the stratosphere.
Dr. Gulick said his previous work drilling into the Chicxulub crater also showed only small amounts of hydrocarbons were present at the time of the impact.
Natalia Artemieva, a senior scientist at the Planetary Science Institute in Tucson, added that soot played a smaller role in driving global cooling than other materials following the asteroid’s impact.
Dr. Kaiho responded to the criticism by saying that his previous soot analysis indicated that it had burned at a higher temperature than what is seen in soot from forest fires and that it all most likely came from the same source, which he said were the rocks at the Chicxulub asteroid impact site.