5/3/17. Extinction of the Dinosaurs. Extinction of Dinosaurs - Causes. #40 Meteorite Impacts III - Dinosaur Extinction, Future Risk, Mitigation

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Paper Scores are posted Please check grades Web Exercise #6 LATE; was Due by 1 pm, Monday 5/1 There is a 2-point penalty for every

If you have questions about Web Exercise #6, contact Fangruo.

Thursday, May 11 th Location HERE Bring Photo ID A practice exam will NOT be posted Optional Question/Answer Session Thursday, 6 to 7 PM

Specifically, you must have a verifiable official University excuse such as three final exams in 24-hour period to schedule a conflict

If you have another final exam scheduled for the same time, then it is probably a combined section (or conflict) final exam and you must

#40 Meteorite Impacts III - Dinosaur Extinction, Future Risk, Mitigation Extinction of the Dinosaurs Dinosaurs include largest land

1 Paper Scores are posted Please check grades Web Exercise #6 LATE; was Due by 1 pm, Monday 5/1 There is a 2-point penalty for every 24-hour period the assignment is late. No Web Exercise #6 will be accepted after 1 pm on Friday, 5/5. If you have questions about Web Exercise #6, contact Fangruo. GEOL 118 Final Exam Format similar to exams 1 and 2 Covers Lectures #27 40 (Global Climate Change I - Meteorite Impacts III) 8:00 AM, Thursday, May 11 th Location HERE Bring Photo ID A practice exam will NOT be posted Optional Question/Answer Session Thursday, 6 to 7 PM in 1065 Lincoln Hall Official University of Illinois policy will be followed for requests for a conflict final exam time. Specifically, you must have a verifiable official University excuse such as three final exams in 24-hour period to schedule a conflict final exam for GEOL 118. If you have another final exam scheduled for the same time, then it is probably a combined section (or conflict) final exam and you must take a conflict exam in that course in accordance with Student Code. #40 Meteorite Impacts III - Dinosaur Extinction, Future Risk, Mitigation Extinction of the Dinosaurs Dinosaurs include largest land animals ever, lived for 160 m.y. (from 225 to ~65 m.y.a.), then extinct abruptly. Why? Argentinosaurus Extinction of Dinosaurs Dinosaurs lived/dominated for 160 million years Extinction of Dinosaurs - Causes Asteroid Impact - effects of collision with Earth by huge meteorite or comet (~10 km), ~65 million years ago; Proposed in 1979 by Luis Alvarez (Nobel physics laureate), Walter Alvarez (geologist) Then, 65 million years ago they went extinct abruptly. Why? 1

Clicker Question: Review Which is closest to the size of the meteorite that created this milewide crater in Arizona?

tremendous force released on impact (equivalent to detonation of ~10,000x entire nuclear arsenal of world at single point)

impact point, producing giant (~200 km wide) crater.

melts large part of crust along with asteroid.

2 Clicker Question: Review Which is closest to the size of the meteorite that created this milewide crater in Arizona? A) One half mile in diameter B) 30 meters (1/50 mile) Extinction of Dinosaurs - Causes Size of meteorite to create ~1 mile wide Meteor Crater, AZ only 30 meters! Effects of 10 km asteroid collision = Due to large size (millions of megatons) and high speed (80,000 km/hr = ~20 km/sec), tremendous force released on impact (equivalent to detonation of ~10,000x entire nuclear arsenal of world at single point) Effects of 10 km asteroid collision - As meteorite hits Earth, jet stream of rock and dust is sent in all directions from impact point, producing giant (~200 km wide) crater. Effects of 10 km asteroid collision - Force from collision converted to shock waves (which move into ground) and heat, which melts large part of crust along with asteroid. Shock waves reflected upward, sending molten rock skyward, igniting global fires, and sending soot into upper atmosphere. Effects of 10 km asteroid collision - Impact also sends large amounts of dust into upper atmosphere. Dust and soot in atmosphere form thick, dark cloud that blocked out Sun around globe for months, also prevented photosynthesis and caused global cooling. 2

Effects of 10 km asteroid collision - Dinosaurs and other organisms starved and froze to death.

Death of the Dinosaurs video: (PBS 23:47-27:47) https://www.youtube.com/watch?

thick) clay layer present at Mesozoic/Cenozoic boundary 1) Evidence from clay layer deposited at very end of

meteorite impact sites, tektites (glassy blebs from rock melting during impact), carbon pieces (from fires) 2)

quartz with shock lamellae tektites Clicker Question: Review What evidence do we have that a meteorite impact

A sediment layer marking the end of the Cretaceous period has high iridium concentration B.

3 Effects of 10 km asteroid collision - Dinosaurs and other organisms starved and froze to death. (Other damage can include giant sea waves, massive earthquakes, longer term acid rain and global warming) The Death of the Dinosaurs video: (PBS 23:47-27:47) 1) Evidence from clay layer deposited at very end of Mesozoic Era - Distinctive thin (several cm thick) clay layer present at Mesozoic/Cenozoic boundary 1) Evidence from clay layer deposited at very end of Mesozoic Era iridium-rich (abundant only in meteorites), metamorphosed quartz (shock lamellae) found in meteorite impact sites, tektites (glassy blebs from rock melting during impact), carbon pieces (from fires) 2) Large, buried impact crater in southeast Mexico - right size (~200 km wide), formed at right time (65 m.y.a.) quartz with shock lamellae tektites Clicker Question: Review What evidence do we have that a meteorite impact wiped out the dinosaurs (and some other species)? A. A sediment layer marking the end of the Cretaceous period has high iridium concentration B. A large crater of the right age exists C. Quartz crystals showing damage from the impact are found in sediments from that time D. All of the above Clicker Question: Opinion If a similar impact happened today, would humanity survive? A. Yes B. No 3

Dinosaur Extinction - Other Models Volcanic Eruptions - Enormous amount of Hawaiian-type volcanic eruptions at ~66 m.y.a. (2 km thick over 0.

Possibly meteorite impact triggered volcanic eruptions, which further blocked sunlight; or may have happened to coincide in time.

Impact of large meteorite is potentially catastrophic future natural disaster; collision of 10-km meteorite occurs only once in ~100 million years; 1-km meteorite can

Disaster? Recent study estimates that over 50 years, risk of dying from meteorite collision = 1 in 75,000 (similar to tornado, higher than lightning).

Asteroids: Deadly Impact video (National Geographic, 8:40-9 from #1, 0-1:20 from #2) https://www.youtube.com/watch?

v=zi ctquxbq9i Mitigation - Meteorite Impacts Meteorite collisions are only natural disaster that we can potentially PREVENT by deflecting or destroying (e.g., with nuclear bomb explosion on object), but we would need much advance warning (~10 years).

4 Dinosaur Extinction - Other Models Volcanic Eruptions - Enormous amount of Hawaiian-type volcanic eruptions at ~66 m.y.a. (2 km thick over 0.5 million km 2 area, larger than France!; volume = million km 3 ) Dinosaur Extinction - Other Models Volcanic Eruptions - eject dust into atmosphere, block sunlight. Possibly meteorite impact triggered volcanic eruptions, which further blocked sunlight; or may have happened to coincide in time. Both mechanisms (and other gradual ones) may apply. Future Meteorite Impact Disaster? Impact of large meteorite is potentially catastrophic future natural disaster; collision of 10-km meteorite occurs only once in ~100 million years; 1-km meteorite can devastate most nations (~1,000 Near Earth Objects that are 1 km), 100 m objects could level whole cities (~20,000 NEOs that are 100-1,000 m) Risk of Future Meteorite Impact Disaster? Recent study estimates that over 50 years, risk of dying from meteorite collision = 1 in 75,000 (similar to tornado, higher than lightning). Risk is ~high because event ( 1 km meteorite impact) has low probability (once in 100,000 years), but huge number of deaths (~1.5 billion). Asteroids: Deadly Impact video (National Geographic, 8:40-9 from #1, 0-1:20 from #2) ZnQ9TL_RA ctquxbq9i Mitigation - Meteorite Impacts Meteorite collisions are only natural disaster that we can potentially PREVENT by deflecting or destroying (e.g., with nuclear bomb explosion on object), but we would need much advance warning (~10 years). Mitigation - Meteorite Impacts Government programs (e.g., NASA) have built a catalog of Near- Earth Objects The table below gives a list of 6 NEO s that have the highest predicted risk of impact Their orbits are known well (but not perfectly) So we can predict times when they will pass close to earth We can also estimate the probability of an impact Our estimates will get better over time- more data Potential impacts are decades away, sizes not too large There are many other NEO s out there (some bigger, less likely) 4

Natural Disasters- Final Words to you Know a little bit about HOW THEY WORK Understand the type of risk (black swans; perfect storms) Assess the risk and its uncertainty Mitigation of risk: Costs

5 Natural Disasters- Final Words to you Know a little bit about HOW THEY WORK Understand the type of risk (black swans; perfect storms) Assess the risk and its uncertainty Mitigation of risk: Costs versus benefits Education Private-sector actions- decisions based on risk Public Sector actions- Do politicians know enough to take action? Do voters know enough? Do government officials know enough? Regulations: Cost versus benefit YOU will be the leaders of your generation 5

Causes of Extinction

Causes of Extinction Extinction the process through which a species disappears from Earth, when the birth rate is less than the death rate. When a species becomes extinct, it no longer exists, which can