Study claims dinosaur-killing asteroid cooled Earth 45 degrees

The giant space rock that wiped out the dinosaurs may have set off a chain of cataclysmic volcanic eruptions on land and undersea, claims a new study that is already dividing scientists.

About 66 million years ago, a 6-mile wide asteroid smacked into Earth, creating the Chicxulub crater in the Yucatan and sparking deadly chaos. Superhot particles rained from the air causing fires across the globe and sending temperatures higher. Then it got worse.

Clouds of particles reflected the sun’s energy away, darkening the skies and cooling Earth at least 45 degrees for several years, scientists said.

And that big hit set off earthquakes close to 100 times stronger than the biggest we’ve seen in modern times.

It was enough to kill off three-quarters of the life on Earth, especially most of the creatures and plants on land.

But there were even more reverberations, possibly deadly ones, the new study says.

New evidence suggests all that shaking triggered massive volcanic eruptions that spewed gases and particles into the air and water too.

A study in Wednesday’s journal Science Advances figures sometime after the asteroid crash, unusual and extra strong eruptions happened on the floor of the oceans, probably in what are now the Pacific and Indian oceans.

The study authors calculate that those ejected a tremendous amount of molten rock underwater — so much that on land it would cover the entire continental United States a couple hundred feet deep or so.

“We’re showing there was a lot more going on than we thought,” said University of Minnesota geophysicist Joseph Byrnes, the study’s lead author. “We’re painting a new sequence of events.”

These underwater volcanic areas — called mid-ocean ridges — often erupt, even today. But this happened on a far bigger scale.

What happened inside the underwater volcanoes is “totally analogous to a can of Coke that gets shaken. The whole thing turns into a frothy mess,” said the University of California, Berkeley geologist Paul Renne, who wasn’t part of the study but said it “illustrates how intertwined everything else is.”

The study’s authors say their work hints that the underwater eruptions helped turn the oceans more acidic and added to extinction carnage, but they said they need more research to go that extra step.

Scientists are split, sometimes heatedly, over what really triggered the worst of the extinction, the impact of the crater and its plumes of debris or other upheavals of the Earth’s crust in the wake of the collision.

A study in 2015 suggested that the collision made volcanic eruptions in India that scientists have long known about, called the Deccan traps, far more intense and deadly.

Read rest at CBS News

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    Robert Beatty

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    With the exception of some ectothermic species such as the leatherback sea turtle and crocodiles, no tetrapods weighing more than 25 kilograms (55 lb) survived (Cretaceous–Paleogene (K–Pg) extinction event) Ref: https://en.m.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event

    These are the 3 groups which would survive toxically high levels of CO2. The first two lay eggs which incubate unattended and would therefore survive while their parents would succumb. The heavy tetrapods are associated with low altitude while smaller tetrapods often reside at a higher altitude where the concentration of CO2 is lower due to its high density.

    So where did all the CO2 come from and why was it an apparently short lived event? Huge volumes of CO2 are stored in the sea as the bicarbonate ion. This ion is only stable at temperatures below 50 degrees centigrade – a temperature easily exceeded by an asteroid impact. This resulted in a volcano of CO2 erupting from the sea which will circle the globe before being reabsorbed back into the sea some days later and leaving a planet with dead carcasses littering the low lands.

    Large asteroids impacting the ocean leave little trace, but can be more devastating to air breathers that impacts on land.

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    Steve Dembo

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    So how did anything survive? Like birds, mammals, etc.? I would think there would only be insects left.

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    Gösta Andersson

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    45 degrees, is that Centigrade or Fahrenheit?

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  • Avatar

    Robert Beatty

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    Worth adding that a large asteroid impact with the ocean not only produces large emission of CO2, but also steam. The steam travels to high altitudes before settling out as clouds which also shade the planet for some time. It is hard to understate the effect a large impact with the sea would have on biological processes, and it may not necessary to invoke catastrophic fire sequences, or traumatic tectonic events to explain the biological consequences.
    Also the Deccan Traps include a KT band in the lower-middle sequence indicating that their initial eruption preceded the Chicxulub impact.
    Ocean asteroid impacts needs more study.

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