Speaker 1: Welcome to brain Stuff from how Stuff works. Hey, brain Stuff,
Speaker 1: it's Christian Seger. Picture what it must have been like
Speaker 1: for the dinosaurs just before they bought the proverbial farm.
Speaker 1: You're probably familiar with the basics of what happened. Sixty
Speaker 1: six million years ago. A massive asteroid hit Earth in
Speaker 1: Mexico's Yucatan Peninsula, which was at the time a shallow sea,
Speaker 1: and suddenly, relative to the long stretch of planetary history,
Speaker 1: there were no more dinosaurs. At least that's the sanitized
Speaker 1: version of the story. For some lucky organisms, death was quick,
Speaker 1: but others probably had to spend some time staggering around
Speaker 1: in a pitch dark nightmareland. It was probably terrible, but
Speaker 1: we don't know much about what the environmental aftermath of
Speaker 1: the asteroids impact was actually like, and that lack of
Speaker 1: precise knowledge makes it tough to know much about why
Speaker 1: some species died and others survived. A new study published
Speaker 1: in the Proceedings of the National Academy of Sciences used
Speaker 1: advanced computer modeling techniques to figure out exactly what kind
Speaker 1: of wretched hellscape drove roughly three quarters of the planet
Speaker 1: species to extinction. The researchers found that the cheek Salube
Speaker 1: asteroid that ushered in the Cretaceous Paleogene extinction most likely
Speaker 1: triggered all sorts of cataclysmic natural disasters like earthquakes, tsunamis,
Speaker 1: and volcanic eruptions, in addition to wildfires ignited by the
Speaker 1: vaporized molten rock that rained down on every corner of
Speaker 1: the planet. The team wanted to look at the long
Speaker 1: term consequences of the amount of soot they think was
Speaker 1: created and what those consequences might have meant for the
Speaker 1: animals that were left. It is not an insignificant amount
Speaker 1: of soot we're talking about here. The scientists estimate that
Speaker 1: these worldwide wildfires that started after the asteroid hit launched
Speaker 1: around fifteen billion tons or thirteen point six billion metric
Speaker 1: tons of fine soot into the atmosphere. Average temperatures on
Speaker 1: Earth's surface and at sea plummeted with a fifty degree
Speaker 1: fahrenheit or twenty eight degrees celsius drop over land and
Speaker 1: a drop of twenty degrees fahrenheit or eleven degrees celsius
Speaker 1: over the oceans for more than a year and a half.
Speaker 1: Photosynthesis would have been impossible for the terrestrial plants that
Speaker 1: weren't damaged or destroyed by the fires, and in the oceans,
Speaker 1: the phytoplankton would have been hit hard enough to tank
Speaker 1: the marine food chain for a few months, our planet's
Speaker 1: energy source was removed and a lot of animals starved.
Speaker 1: Interestingly enough, the research team's models found that a fraction
Speaker 1: of soot in the atmosphere probably would have entirely shut
Speaker 1: down photosynthesis for a year. Actually, only five billion tons
Speaker 1: or four point five billion metric tons of soot would
Speaker 1: have done the trick. They also found that as Earth
Speaker 1: sees surface and lower atmosphere below the soot level cooled,
Speaker 1: All that soot absorbed the Sun's light, heating and changing
Speaker 1: the chemistry of the upper atmosphere, destroying the ozone layer
Speaker 1: in the process. All the water in the atmosphere caused
Speaker 1: by the sudden warming eventually condensed into ice, creating a
Speaker 1: feedback loop that would very suddenly scour all the soot
Speaker 1: out of the atmosphere over the course of just a
Speaker 1: few months. Now For comparison, the lead author on this study,
Speaker 1: Charles Bairdeen, says the amount of soot created by nuclear
Speaker 1: warfare would be much less than what the planet saw
Speaker 1: during this extinction. Today's episode was written by Jescelyn she Wilds,
Speaker 1: produced by Dylan Fagan, and For more on this and
Speaker 1: other topics, please visit us at how stuff works dot
Speaker 1: com