1 00:00:02,040 --> 00:00:07,600 Speaker 1: Welcome to brain Stuff from how Stuff works. Hey, brain Stuff, 2 00:00:07,600 --> 00:00:10,119 Speaker 1: it's Christian Seger. Picture what it must have been like 3 00:00:10,240 --> 00:00:14,280 Speaker 1: for the dinosaurs just before they bought the proverbial farm. 4 00:00:14,320 --> 00:00:17,480 Speaker 1: You're probably familiar with the basics of what happened. Sixty 5 00:00:17,600 --> 00:00:21,720 Speaker 1: six million years ago. A massive asteroid hit Earth in 6 00:00:21,880 --> 00:00:25,919 Speaker 1: Mexico's Yucatan Peninsula, which was at the time a shallow sea, 7 00:00:26,079 --> 00:00:29,840 Speaker 1: and suddenly, relative to the long stretch of planetary history, 8 00:00:30,240 --> 00:00:33,640 Speaker 1: there were no more dinosaurs. At least that's the sanitized 9 00:00:33,720 --> 00:00:37,320 Speaker 1: version of the story. For some lucky organisms, death was quick, 10 00:00:37,520 --> 00:00:40,800 Speaker 1: but others probably had to spend some time staggering around 11 00:00:40,800 --> 00:00:44,720 Speaker 1: in a pitch dark nightmareland. It was probably terrible, but 12 00:00:44,800 --> 00:00:48,000 Speaker 1: we don't know much about what the environmental aftermath of 13 00:00:48,040 --> 00:00:52,000 Speaker 1: the asteroids impact was actually like, and that lack of 14 00:00:52,040 --> 00:00:55,280 Speaker 1: precise knowledge makes it tough to know much about why 15 00:00:55,400 --> 00:00:59,840 Speaker 1: some species died and others survived. A new study published 16 00:00:59,840 --> 00:01:03,400 Speaker 1: in the Proceedings of the National Academy of Sciences used 17 00:01:03,440 --> 00:01:08,039 Speaker 1: advanced computer modeling techniques to figure out exactly what kind 18 00:01:08,080 --> 00:01:12,600 Speaker 1: of wretched hellscape drove roughly three quarters of the planet 19 00:01:12,720 --> 00:01:17,240 Speaker 1: species to extinction. The researchers found that the cheek Salube 20 00:01:17,280 --> 00:01:22,600 Speaker 1: asteroid that ushered in the Cretaceous Paleogene extinction most likely 21 00:01:22,680 --> 00:01:28,640 Speaker 1: triggered all sorts of cataclysmic natural disasters like earthquakes, tsunamis, 22 00:01:28,840 --> 00:01:33,000 Speaker 1: and volcanic eruptions, in addition to wildfires ignited by the 23 00:01:33,120 --> 00:01:37,760 Speaker 1: vaporized molten rock that rained down on every corner of 24 00:01:37,800 --> 00:01:40,720 Speaker 1: the planet. The team wanted to look at the long 25 00:01:40,880 --> 00:01:44,480 Speaker 1: term consequences of the amount of soot they think was 26 00:01:44,560 --> 00:01:48,400 Speaker 1: created and what those consequences might have meant for the 27 00:01:48,440 --> 00:01:52,360 Speaker 1: animals that were left. It is not an insignificant amount 28 00:01:52,400 --> 00:01:55,440 Speaker 1: of soot we're talking about here. The scientists estimate that 29 00:01:55,520 --> 00:02:00,280 Speaker 1: these worldwide wildfires that started after the asteroid hit launched 30 00:02:00,360 --> 00:02:06,280 Speaker 1: around fifteen billion tons or thirteen point six billion metric 31 00:02:06,360 --> 00:02:11,560 Speaker 1: tons of fine soot into the atmosphere. Average temperatures on 32 00:02:11,680 --> 00:02:15,320 Speaker 1: Earth's surface and at sea plummeted with a fifty degree 33 00:02:15,360 --> 00:02:19,679 Speaker 1: fahrenheit or twenty eight degrees celsius drop over land and 34 00:02:19,800 --> 00:02:23,600 Speaker 1: a drop of twenty degrees fahrenheit or eleven degrees celsius 35 00:02:23,720 --> 00:02:27,519 Speaker 1: over the oceans for more than a year and a half. 36 00:02:27,840 --> 00:02:32,200 Speaker 1: Photosynthesis would have been impossible for the terrestrial plants that 37 00:02:32,360 --> 00:02:36,480 Speaker 1: weren't damaged or destroyed by the fires, and in the oceans, 38 00:02:36,840 --> 00:02:40,720 Speaker 1: the phytoplankton would have been hit hard enough to tank 39 00:02:40,960 --> 00:02:44,720 Speaker 1: the marine food chain for a few months, our planet's 40 00:02:44,800 --> 00:02:49,280 Speaker 1: energy source was removed and a lot of animals starved. 41 00:02:49,720 --> 00:02:53,880 Speaker 1: Interestingly enough, the research team's models found that a fraction 42 00:02:54,000 --> 00:02:57,640 Speaker 1: of soot in the atmosphere probably would have entirely shut 43 00:02:57,680 --> 00:03:03,080 Speaker 1: down photosynthesis for a year. Actually, only five billion tons 44 00:03:03,200 --> 00:03:07,400 Speaker 1: or four point five billion metric tons of soot would 45 00:03:07,440 --> 00:03:10,280 Speaker 1: have done the trick. They also found that as Earth 46 00:03:10,440 --> 00:03:15,119 Speaker 1: sees surface and lower atmosphere below the soot level cooled, 47 00:03:15,520 --> 00:03:19,960 Speaker 1: All that soot absorbed the Sun's light, heating and changing 48 00:03:19,960 --> 00:03:24,120 Speaker 1: the chemistry of the upper atmosphere, destroying the ozone layer 49 00:03:24,240 --> 00:03:28,080 Speaker 1: in the process. All the water in the atmosphere caused 50 00:03:28,120 --> 00:03:32,200 Speaker 1: by the sudden warming eventually condensed into ice, creating a 51 00:03:32,280 --> 00:03:37,000 Speaker 1: feedback loop that would very suddenly scour all the soot 52 00:03:37,160 --> 00:03:39,880 Speaker 1: out of the atmosphere over the course of just a 53 00:03:39,920 --> 00:03:44,600 Speaker 1: few months. Now For comparison, the lead author on this study, 54 00:03:44,800 --> 00:03:48,560 Speaker 1: Charles Bairdeen, says the amount of soot created by nuclear 55 00:03:48,640 --> 00:03:52,200 Speaker 1: warfare would be much less than what the planet saw 56 00:03:52,520 --> 00:04:00,320 Speaker 1: during this extinction. Today's episode was written by Jescelyn she Wilds, 57 00:04:00,320 --> 00:04:03,040 Speaker 1: produced by Dylan Fagan, and For more on this and 58 00:04:03,160 --> 00:04:06,200 Speaker 1: other topics, please visit us at how stuff works dot 59 00:04:06,240 --> 00:04:19,200 Speaker 1: com