Chicxulub Impact Caused Global Wildfires and Superheated Atmosphere, New Study Suggests

New Mechanism for Dinosaur Extinction

A recent paper in the Journal of Geophysical Research: Biogeosciences suggests a specific mechanism for the mass extinction event 66 million years ago that wiped out dinosaurs and three-quarters of Earth's species. The study indicates that the asteroid impact generated an immense dust cloud, which subsequently superheated the upper atmosphere. This atmospheric heating would have charbroiled unprotected organisms and ignited widespread wildfires across the globe.

The Alvarez Hypothesis and Chicxulub Crater

The prevailing explanation for this catastrophic event is the Alvarez hypothesis, proposed by Luis and Walter Alvarez in 1980. Their theory was based on the discovery of unusually high concentrations of iridium at the Cretaceous-Paleogene boundary, a metal more common in asteroids than on Earth. This led them to conclude that a massive asteroid or comet impact caused the extinction.

Further evidence supports this hypothesis with the identification of the Chicxulub crater in Mexico's Yucatan Peninsula as the likely impact site. Discovered in the late 1970s, the impactor that created this crater was estimated to be between 11 and 81 kilometers (7 to 50 miles) in size. The energy released by this impact was over a billion times greater than the atomic bombs dropped on Hiroshima and Nagasaki.

Impact and Environmental Consequences

The Chicxulub impact was powerful enough to melt, shock, and eject granite from deep within the Earth. It likely triggered a megatsunami and ejected vaporized rock and sulfates into the atmosphere. The new research adds to this understanding by detailing how the atmospheric effects of the dust cloud directly contributed to the widespread destruction of life through extreme heat and fires.