When the dinosaur-destroying asteroid collided with Earth 66 million years in the past, large quantities of sulfur – volumes greater than have been beforehand thought – have been thrown excessive above land into the stratosphere, a brand new examine finds.


As soon as airborne, this huge cloud of sulfur-bearing gases blocked the Solar and cooled Earth for many years to centuries, then fell down as deadly acid rain on Earth, altering the chemistry of the oceans for tens of 1000’s of years, which is longer than beforehand thought, the examine discovered.

The findings present that “we have underestimated the quantity of this sulfur that this asteroid influence created,” examine co-researcher James Witts, a lecturer within the Faculty of Earth Sciences on the College of Bristol within the UK, advised Dwell Science.

In consequence, “the local weather change that was related to it was a lot better maybe than we thought beforehand”.

The truth that sulfur continued pouring down on Earth’s floor for therefore lengthy could assist clarify why it took so lengthy for all times, particularly marine life, to get well, as a few of the sulfur that fell onto the land would have then washed away into the oceans, Witts stated.

Associated: What occurred when the dinosaur-killing asteroid slammed into Earth?

Unintended discovering

The researchers’ discovering was fully serendipitous. “It was not one thing that was deliberate in any respect,” Witts stated.

The group had initially deliberate to check the geochemistry of historical shells close to the Brazos River in Falls County, Texas – a novel place that was underwater in the course of the end-Cretaceous extinction, when the non-avian dinosaurs died out.


It is also not too removed from the Chicxulub crater in Mexico’s Yucatan Peninsula, the place the 6-mile-wide (10 kilometers) asteroid struck.

The researchers took a number of sediment samples on the web site, which they hadn’t deliberate on doing.

These samples have been dropped at the College of St Andrews in Scotland, the place examine co-researcher Aubrey Zerkle, a geochemist and geobiologist, analyzed the totally different sulfur isotopes, or variations of sulfur which have a special variety of neutrons of their nuclei.

The researchers discovered “a really uncommon sign” – the sulfur isotopes had surprising tiny adjustments to their lots, Witts stated. Such mass adjustments happen when sulfur enters the ambiance and interacts with ultraviolet (UV) gentle.

“That may actually solely occur in two eventualities: both in an environment that does not have any oxygen in it or when you might have a lot sulfur, it is gone actually excessive up into an oxygenated ambiance,” Witts stated.

Earth is about 4.5 billion years previous, and it has been enveloped by an oxygenated ambiance since about 2.Three billion years in the past.

“We are the first individuals to see this kind of factor in way more current instances,” a minimum of in sediments that are not on the Earth’s poles, Witts stated.


(That is as a result of volcanic eruptions launch sulfur excessive into the ambiance, which might combine with snow and find yourself in excessive concentrations in ice cores on the poles, the place there is no such thing as a different sulfur or sulfate to dilute the sign, Witts stated.)

“You do not see [this signal] in marine rocks,” he stated. “The ocean has its personal isotopic signature which completely dilutes the tiny quantity of sulfur from these volcanoes.”

The truth that this sign is current in marine rock from the Cretaceous exhibits that, “there will need to have been a heck of a variety of sulfur within the ambiance after this influence occasion,” Witts stated.

“And that, in fact, has an enormous implication for local weather change associated to the influence as a result of sulfur aerosols, we all know from fashionable volcanic eruptions, trigger cooling.”

Lots of the sulfur got here from the sulfur-rich limestone on the Yucatan Peninsula.

“If the asteroid had hit someplace else, maybe there would not have been as a lot sulfur launched into the ambiance and the local weather change that adopted won’t have been as extreme,” Witts stated. “And due to this fact the extinction occasion won’t have been so unhealthy.”


Earlier estimates of the sulfur aerosols getting into Earth’s ambiance after the asteroid influence vary from about 30 to 500 gigatons; in line with local weather fashions, this sulfur would have became sulfate aerosols, which might have precipitated 3.6 to 14.Four levels Fahrenheit (2 to eight levels Celsius) cooling of the Earth’s floor for a number of a long time after the influence.

However the brand new discovering means that as a result of the sulfur quantity was increased, the local weather change might have been much more extreme.

The examine was printed on-line Monday (March 21) within the journal Proceedings of the Nationwide Academy of Sciences.

Associated content material:

The 5 mass extinction occasions that formed the historical past of Earth

10 extraordinary dinosaur discoveries from 2021

Photographs: Dinosaur tracks reveal Australia’s ‘Jurassic Park’

This text was initially printed by Dwell Science. Learn the unique article right here.


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