A new study indicates that when the dinosaur-killing asteroid struck the Earth 66 million years ago, vast amounts of sulfur were hurled into the stratosphere - volumes far greater than previously imagined.
This massive cloud of sulfur-bearing gases, once airborne, blocked the Sun and cooled Earth for decades to centuries before falling as dangerous acid rain and altering the chemistry of the oceans for tens of thousands of years, the study noted.
According to study co-researcher James Witts, a lecturer at the School of Earth Sciences at the University of Bristol in the United Kingdom, "we've underestimated the amount of this sulfur that this asteroid impact created."
As a result, the climate change linked with it may have been far higher than previously anticipated.
The fact that sulfur continued to rain down on the Earth's surface for so long may help explain why it took so long for life, particularly marine life, to recover, as some of the sulfur that fell onto the land would have been washed away into the oceans, according to Witts.
The researchers' discovery was purely coincidental: "It was not something that was planned at all," Witts said.
The researchers had intended to investigate the geochemistry of ancient shells near the Brazos River in Falls County, Texas - a unique location that was submerged during the end-Cretaceous extinction, when non-avian dinosaurs perished.
It's also not far from the Chicxulub crater in Mexico's Yucatan Peninsula, which was struck by a 6-mile-wide (10-kilometer) asteroid.
The scientists took a few sediment samples at the site, something they hadn't intended on.
The researchers discovered "a very unusual signal" - the sulfur isotopes' masses showed very little fluctuations, according to Witts. When sulfur enters the atmosphere and interacts with ultraviolet (UV) light, mass changes occur.
The presence of this signal in Cretaceous marine rock indicates that there must have been a lot of sulfur in the atmosphere following the impact event, according to Witts.
Previous estimates of the sulfur aerosols entering Earth's atmosphere after the asteroid impact range from 30 to 500 gigatons; according to climate models, this sulfur would have converted to sulfate aerosols, causing 3.6 to 14.4 degrees Fahrenheit (2 to 8 degrees Celsius) cooling of the Earth's surface for several decades after the impact.
The latest discovery, however, shows that because the sulfur content was higher, the climatic change could have been far more severe.
The study was published online Monday in the journal Proceedings of the National Academy of Sciences.
