Mass Extinctions

When life on earth had some very, very, very bad days

End-Permian Extinction

Credit Where Credit Is Due

© 2013 The Teaching Company 36 ½-hour lectures

Augmentation from personal library and internet resources Debate always exists in science Presenting my take on the current consensus

Astronomers Look “Up, Up and Away”

“What is its composition?” “How did it form?” “What is its physical condition?”

We have visited very few places to make direct measurements

How Do We Know What We Know?

Application of rigorous studies and experiments in the field and in laboratories on earth

Spectroscopy of elements & molecules as a function of temperature & pressure

Dynamics of earth’s landforms - tectonics, volcanism, erosion, sedimentation, etc.

Chemistry of earth resource formation Almost everything we know about the cosmos has a foundation of research done here Astrobiology is receiving increasing focus - Is there life elsewhere?

Earth is the only example with life in the universe - all we know comes from studies here Understanding life and its history on Earth will help us ‘decipher’ what we see on other worlds

Brief History of Life on Earth

4.6 bya Earth’s birth 3.5 bya photoautotrophs (stromatolites) 2.7 bya eukaryotes (cells with nuclei) 2.1 bya algae fossils 580 mya metazoans (Ediacaran) 530 mya molluscans, arthropods, echinoderms, chordate (Cambrian) 513 mya oldest conodonts (vertebrates) 430 mya jawed fishes 428 mya oldest arthropod fossil on land 425 mya nonvascular land plant 420 mya oldest vascular plant 418 mya lobe finned fish 400 mya oldest insect 370 mya pteridosperms (seed ferns) 365 mya tetrapods (amphibian) 359 mya true forests (Carboniferous) 330 mya oldest amniote (reptile) 310 mya oldest flying insect 310 mya oldest synapsid 228 mya oldest dinosaur 220 mya oldest mammal 200 mya oldest pterosaur 150 mya oldest bird 130 mya oldest placental mammal 125 mya oldest flowering plant 55 mya first true primate 4.2 mya early hominin

190,000 ya modern humans

Have You Seen Any of These Magnificent Creatures?

Extinction Rules the Earth

25 significant extinction events have been identified

Estimated 99% of all species that ever existed are extinct Estimated 10-14 million species today Over 1 billion species have existed on earth and are gone Earth has been a fantastic laboratory for new species experimentation

Extinction may be a critical ‘driver’ for evolution Extinction clears ecosystems allowing rapid diversification & radiation of new species Death provides opportunity

Therapsids/Permian Archosaurs/Triassic Dinosaurs/Jurassic-Cretaceous Mammals/Now Who?/Future

We owe our existence to extinctions

Extinction Causes

Asteroid & comet impacts Earth’s astronomical cycles Magnetic field reversals Plate tectonics Volcanism Global warming & cooling Glaciations & glacier melting Sea level rise & fall Ocean anoxia (lack of oxygen) Methane clathrate release Ocean euxinia (hydrogen sulfide release) Ocean overturn - disruption of thermo-haline circulation Nova, supernova, gamma ray burst Life

Mass Extinctions

20% or more families ‘vanish’ Extends across all ecosystems Sudden and short <1,000,000 years

Taxonomy - Classification of Life

The Big Five 17% families, 50% genera, 75% species 23% families, 48% genera, 70-75% species 57% families, 83% genera, 96% species 19% families, 50% genera, 70% species 27% families, 57% genera, 60-70% species

Permian World (299-251 million years ago)

Permian Climate

Early Permian: Still in ice age from late Carboniferous Average global temperature ~12° C (54° F), O2 ~ 30%, CO2 ~ 300ppm

Current global average temperature ~14° C (57° F) Gradual warming melted ice by middle Permian Drying & warming continued through late Permian Much of interior became arid with wet and dry seasons, cool and dry periods Carboniferous swamp forests replaced by conifers, seed ferns and drought tolerant plants Tropics were covered with swampy forests Late Permian average global temperature ~21° C (70° F), O2 ~ 17%, CO2 ~ 1800ppm Life on earth was diverse, vibrant and thriving on the land and in the seas

Permian Oceans

Permian Oceans

Permian Oceans

Eurypterids (Sea Scorpions)

Permian Reptiles

The Age of Reptiles began in the Permian. Turtles, Tortoises, Terrapins Archosaurs, Dinosaurs Lizards, Snakes, Crocodilians, Birds Pelycosaurs, Therapsids, Cynodonts, Dicynodonts Mammals

Synapsids dominated the Permian land

Permian Land

Permian Land

Permian Land Dicynodonts

herbivores

Gorgonopsians

Carnivores

The Victims

Foraminifera 97% Fusulinids 100%

Amphibians 80%

Radiolaria (plankton) 99% Reptiles 80%

Anthozoa (sea anemones, corals, etc.) 96% Tabulate & rugose corals 100%

Insects: 8-9 orders lost Only mass extinction

Bryozoans 79% Fenestrates, trepostomes & cryptosomes 100%

Forests Virtually disappeared

Brachipods 96% Orthids & productids 100%

Bivalves 59%

Gastropods (snails) 98%

Ammonites 97%

Crinoids (echinoderm) 98%

Blastoids (echinoderm) 100%

Trilobites 100%

Eurypterids 100%

Ostracods (small crustaceans) 59% Acanthodians 100%

Clue #1 - Stream Morphology

Meandering Braided

Meandering and braided streams leave differing sedimentation patterns Meandering stream channels are stabilized by vegetation At P-T boundary meandering changed to braided

∴ At P-T boundary vegetation had decreased

Clue #2 - Coal Beds

Coal is the carbonized remains of plants from vast prehistoric forests and swamps Extensive coal deposits were laid during the Carboniferous To a lesser extent coal was deposited through the Permian These coal deposits abruptly end at the P-T boundary

∴ The vigorous plant growth stopped

Clue #3 - Fungal Spore Level

Fungi are primary decomposers, reducing ‘the dead’ to carbon dioxide and water Fungal spores in sediments tell a lot about the environment at the time

Change in fungal types and significant increase in fungal spore levels at P-T boundary

∴ Significant increase in decomposing biomass

Clue #4 - Sediment 13C/12C Ratio

Clue #4 - Sediment 13C/12C Ratio

Photosynthesis in plant preferentially incorporates slightly more 12CO2 than 13CO2 Atmosphere becomes slightly depleted in 12CO2 raising 13C/12C - reflected in sediments

Significant drop in 13C/12C at P-T boundary Biogenic 12C removed by life had been returned to atmosphere

Decomposition of massive amounts of previous living biomass Massive methane release

Photosynthesis not removing 12CO2

∴ Photosynthesis has essentially ceased

Clue #5 - Japanese Radiolarian Siliceous Oozes

Radiolaria are common protozoan zooplankton that produce silica skeletons

Skeletal remains make up a large part of the cover of the ocean floor as siliceous ooze

∴ Oceans became anoxic

Siberian Flood Basalt Volcanics

Massive eruptions of basaltic lavas Form the basaltic traps

Mantle Plume Eruptions

Flood basalts Mid-oceanic ridges African rift valley Hot spot volcanoes - Iceland, Hawaii

Basaltic Lava Eruption - Kilauea

Laki (Lakagigar) in Iceland 1783-4

June 8, 1783 to February 7, 1784 (8 months) 27 kilometer long fissure with 130 craters Lava fountains 800 to 1400 m (2400 to 4200 ft) high 14 cubic kilometers of basaltic lava covering 565 square kilometers

Kilauea - 4 cubic kilometers in 30 years 304 million tons of carbon dioxide 120 million tons of sulfur dioxide 8 million tons of hydrogen fluoride Carried 15 kilometers high by the convective eruption column

Chemistry

Carbon dioxide - CO2

Greenhouse gas can raise average global temperatures Combines with water to form Carbonic Acid (weak acid) that can lower ocean pH

Lower pH can inhibit growth of animals that make CaCO3 structures Laki eruption = 0.06 ppm CO2

Sulfur dioxide - SO2

Combines with water to form Sulfuric Acid (strong acid) and aerosol Aerosol blocks sunlight causing cooling

1991 Pinatubo eruption: 0.5°C (0.9°F) global temperature reduction [1/6th Laki SO2] Inhalation of aerosol causes pulmonary distress, fluid buildup in lungs, death Very soluble in water and removed from atmosphere by rain

Resulting rain is acidic (acid rain) Acid rain damages plants - base of the food chain

Hydrogen fluoride - HF

Causes skeletal fluorosis, deformation & embrittlement Soluble in water, forming hydrofluoric acid - damaging to living tissue

Additional acid load in acid rain

Global Impact of Laki Eruption

Iceland Grass growth stunted, fish catches decreased dramatically 80% of sheep, 50% of cattle, 50% of horses died from famine and HF/SO2 poisoning Icelandic population decreased by 25% (10,000) famine and HF/SO2 poisoning

Europe Heavy SO2 haze covered much of Western Europe UK - 23,000 died from poisoning, 8,000 more from famine European death toll of 142,000

Monsoon Regions Weakened African and Indian monsoon circulation

Low Nile River flow resulted in famine killing 1/6 of Egypt’s population India - the Chalisa famine of 1783-4 resulted in 11 million deaths

North America Winter 1783-4 longest and coldest on record

4.8°C below normal Mississippi River froze as far south as New Orleans

Global death toll: 12,000,000 - deadliest eruption in historical times

One of the most climatic and socially repercussive events of the last millennium

‘Thought Experiment’

Imagine

Laki eruption big enough to raise CO2 level 100 ppm (anthropologic CO2) The eruption would be 1700 times bigger

SO2 would be 1700 times greater (10,200 times greater than Pinatubo)

For volcanic events, SO2 impact will dominate initially over CO2 It takes much longer for CO2 levels to increase to a level that will cause an effect Now imagine even bigger - MUCH BIGGER - 20 TIMES BIGGER

Laki versus Siberian Basaltic Eruptions

Laki Siberia X-factor Duration 8 Months 200,000 to 1 million years 6x105

Lava volume 14 cubic kilometers 2-4 million cubic kilometers 2x105

Lava area 565 square kilometers 4-7 million sq kilometers 1x105

Carbon dioxide 304 million tons (0.06 ppm) 55 trillion tons (10,000 ppm) 2x105

Sulfur dioxide 120 million tons 4 trillion tons 3x104

A series of multiple eruptions, not a single eruption.

Permian Extinction in a Single Chart

The Extinction (1)

Late Permian average global temperature ~21° C (70° F), O2 ~ 17%, CO2 ~ 1800ppm

Current global average temperature ~14° C (57° F) Siberian eruptions eject massive amounts of CO2, SO2, HF, etc.

Local Siberian ecosystems exterminated by local high SO2, HF, etc.

The Extinction (2)

SO2 initiates rapid global cooling and a global volcanic ‘winter’

Plants/animals conditioned to warm climate stressed/killed by colder climate Cold temperatures lower photosynthetic efficiency - plant growth reduced

Acid rain (undiluted lemon juice) causes more damage to plants Base of food chain weakened Acid run-off would begin stressing local continental shelf reef communities

The Extinction (3)

Greenhouse warming from atmospheric carbon eventually overcomes SO2 cooling

CO2 may have spiked to 7800ppm Catastrophic global warming occurs

Atmospheric temperatures rise by 10 to 30° C (18 to 54° F) Average temperatures of 26 to 46° C (79 to 115° F)

Dramatically high temperatures causes photosynthesis and food chain to collapse

Decimation of land plants and animals Equatorial region and interior of Pangea becomes dry, hot, lifeless wasteland

The Extinction (4) The huge ocean ecosystem exhibits significant chemical and temperature inertia

Negative impact lags those on land

Ocean surface temperatures rise and pH decreases (SO2, CO2)

Lower pH & higher temperatures inhibit growth of animals that make CaCO3 structures Reef communities begin to collapse Photosynthesis (phytoplankton, algae) also begins to collapse Base of the marine food chain is being destroyed Marine ecosystem begins to completely collapse

The Extinction (5)

Ocean circulation driven by temperature gradients Sinking and rising of ocean currents oxygenates the ocean depths During extinction ocean surface temperatures become so high surface waters could not cool enough to sink

Ocean circulation stopped Oceans become anoxic, suffocating animal life Anoxic conditions promote anaerobic bacterial growth Anaerobic activity produces hydrogen sulfide (H2S), creating euxinic conditions Hydrogen sulfide is very toxic, dealing the final blow to marine life

The Extinction (6)

Methanogenic bacteria in the deep cold oceans make methane that become trapped in hydrates/clathrates

Methane clathrates are very sensitive to rising temperatures, releasing methane Rising ocean temperatures caused release of methane from these ocean clathrates Methane is 10X stronger greenhouse gas than CO2 Methane increases global temperatures, causing release of more methane… This is a positive feedback loop Earth came close to having a runaway global warming event that would have eradicated all complex metazoan life

The Aftermath

Extinction took as long as 80,000 years to as short as 2,100 years

Greater than 80% of life on land; greater than 96% of marine life Meishan Shangsi formation of South China

Sedimentary formation containing fossilized reef community spanning extinction event Before the extinction: 333 species After the extinction: 2 species Extinction rate > 99%

The Aftermath

Earth was a very lonely and empty place Environment: 21-24° C, 12-13% O2 (12-13,000 ft), 2000 ppm CO2

5 million years for ‘dead zone’ to become habitable Total recovery time at least 10 million years

The first dinosaur from surviving archosaur The first mammal from surviving therapsid

Four Simple Molecules

CO2, SO2, CH4, H2S Found in molecular gas clouds where stars, and Earth, were and are created The C, O, S, H, etc. in our bodies came from this molecular cloud These simple molecules almost caused the extinction of all complex life on Earth

November 7, 2015

Cretaceous World - 65 MYA

Deccan flood basalt eruptions: 512,000 cubic kilometers

1/6th Siberian event