AceHistoryDesk – The asteroid which wiped out the dinosaurs ejected 2,000 gigatonnes of dust into the Earth’s atmosphere and unleashed a climate catastrophe, researchers have revealed.

Ace Press News From Cutting Room Floor: Published: Oct.31; 2023: Reuters News Agency: TELEGRAM Ace Daily News Link https://t.me/+PuI36tlDsM7GpOJe

The asteroid struck Mexico’s Yucatan Peninsula 66 million years ago, erasing three-quarters of the world’s species and causing wildfires, quakes, a massive shock wave in the air and huge standing waves in the seas.

But the final blow for many species may have unfolded in the following years, as the skies were darkened by clouds of debris and temperatures plunged.

Dust from pulverised rock ejected into the atmosphere from the impact site may have choked the atmosphere and blocked plants from harnessing sunlight for life-sustaining energy in a process called photosynthesis.

Researchers ran palaeoclimate simulations based on sediment unearthed at a North Dakota palaeontological site called Tanis that preserved evidence of the post-impact conditions, including the prodigious dust fallout.

The simulations showed this fine-grained dust could have blocked photosynthesis for up to two years by rendering the atmosphere opaque to sunlight and remained in the atmosphere for 15 years, said planetary scientist Cem Berk Senel of the Royal Observatory of Belgium and Vrije Universiteit Brussel.

Their study was published in the journal Nature Geoscience.

While prior research highlighted two other factors — sulphur released after the impact and soot from the wildfires — this study indicated dust played a larger role than previously known.

‘It was cold and dark for years’ 

The dust, silicate particles measuring about 0.8–8.0 micrometres, formed a global cloud layer.

The particles were spawned from the granite and gneiss rock pulverised in the violent impact that gouged the Yucatan’s Chicxulub crater, 180 kilometres wide and 20 kilometres deep.

In the aftermath, Earth experienced a drop in surface temperatures of about 15 degrees Celsius.

“It was cold and dark for years,” Vrije Universiteit Brussel planetary scientist and study co-author Philippe Claeys said.

Earth descended into an “impact winter,” with global temperatures plummeting and primary productivity — the process land and aquatic plants and other organisms use to make food from inorganic sources — collapsing.

This caused a chain reaction of extinctions.

As plants died, herbivores starved. Carnivores were left without prey and perished. In marine realms, the demise of tiny phytoplankton caused food webs to crash.

“While the sulphur stayed about eight to nine years, soot and silicate dust resided in the atmosphere for about 15 years after the impact,” Royal Observatory of Belgium planetary scientist and study co-author Özgür Karatekin said.

“The complete recovery from the impact winter took even longer, with pre-impact temperature conditions returning only after about 20 years.”

The asteroid, estimated at 10–15km wide, brought a cataclysmic end to the Cretaceous Period.

The dinosaurs, aside from their bird descendants, were lost, as were the marine reptiles that dominated the seas and many other groups.

The big beneficiary were the mammals, who until then were bit players in the drama of life but were given the opportunity to become the main characters.

“Biotic groups that were not adapted to survive dark, cold and food-deprived conditions for almost two years would have experienced massive extinctions,” Dr Karatekin said.

“Fauna and flora that could enter a dormant phase, for example, through seeds, cysts or hibernation in burrows.

“(They) were able to adapt to a generalistic lifestyle, not dependent on one particular food source, generally survived better, like small mammals.”

Without this disaster, dinosaurs might still dominate today.

“Dinos dominated Earth and were doing just fine when the meteorite hit,” Dr Claeys said.

“Without the impact, my guess is that mammals, including us, had little chance to become the dominant organisms on this planet.”

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