Study: Soot may have snuffed out the dinosaurs

TOHOKU, Japan, July 15 (UPI) -- Because there weren't enough already, scientists in Japan have offered a new theory for how dinosaurs met their demise.

Massive amounts of stratospheric soot sprayed skyward by asteroids triggered global cooling, drought and halted marine photosynthesis. The soot worked swiftly to snuff out both dinosaurs and ammonites, a group of ancient ocean mollusks.

Researchers arrived at their new theory through a combination of geologic evidence and climate modeling.

Chemical analysis suggests ancient soot recovered from both Haiti, near the impact site, and Spain, far from the impact site, was forged by the same high-energy impact -- the Chicxulub asteroid that slammed into Earth some 66 million years ago.

Using a global climate model designed by scientists at the Meteorological Research Institute, researchers calculated how much of the light-absorbing aerosol would be necessary to cause global cooling.

Scientists believe the Chicxulub impact ignited a massive swath of oil-rich land in the Yucatan Peninsula, further fueling the flow of soot into the atmosphere. It's possible as much as 60 billion tons of carbon burned in the wake of the fiery impact.

The researchers from Tohoku University published their findings in the journal Scientific Reports.

"The soot aerosols caused sufficiently colder climates at mid–high latitudes and drought with milder cooling at low latitudes on land," researchers wrote in their paper, "in addition to causing limited cessation of photosynthesis in global oceans within a few months to two years after the impact, followed by surface-water cooling in global oceans in a few years."

The team of scientists are now looking at other extinction events to better understand the succession of events that can lead to the disappearance of biodiversity.