2016-06 Mass extinction SS - u3asites.org.uk€¦ · MASS EXTINCTION LATE DEVONIAN EVENT 375-360 MA...
Transcript of 2016-06 Mass extinction SS - u3asites.org.uk€¦ · MASS EXTINCTION LATE DEVONIAN EVENT 375-360 MA...
MASS EXTINCTION
Halesworth & District
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Signs indicate an imminent
6th Mass Extinction
and this time
Humans are the cause
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MASS EXTINCTION
� A Mass Extinction Event is a widespread and rapid
decrease in the amount of life (species) on Earth
� There is a sharp change in diversity and abundance of
multi-cellular organisms
� Rate of extinction increases with respect to the rate of
speciation
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MASS EXTINCTION
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MASS EXTINCTION
� ORDOVICIAN-SILURIAN EVENTS
� 450-440 MA – two events
� Killed off
� 27% of all families
� 57% of all genera
� 60-70% of all species
� Ranked second largest of five mass extinction events
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MASS EXTINCTION
� LATE DEVONIAN EVENT
� 375-360 MA
� Killed off
� 19% of all families
� 50% of all genera
� 70% of all species
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MASS EXTINCTION
� PERMIAN-TRIASSIC EVENT
� 252 MA
� Killed off
� 57% of all families
� 83% of all genera
� 90-96% of all species
� Ranked largest of five extinction events
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MASS EXTINCTION
� TRIASSIC-JURASSIC EVENT
� 201MA
� Killed off 23% of all families
� 48% of all genera
� 70-75% of all species
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MASS EXTINCTION
� CRETACEOUS-PALEOGENE EVENT
� 66MA
� Killed off� 17% of all families
� 50% of all genera
� 75% of all species
� All non-avian dinosaurs became extinct
� Speculation as to cause but thought to be due to asteroid hit
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RECOVERY
� Usually only species survive that have the ability to live in diverse habitats
� Later, species diversify and occupy empty niches
� Generally biodiversity recovers 5-10 million years after extinction event
� Recovery may take 15-30 million years after a severe mass extinction event
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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PLATE TECTONIC MOVEMENT
� Very slow process
� Ocean floor spreading
� Some earthquake faults very weak
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MASSIVE VOLCANISM� Now, seismic monitoring gives some warning of eruption
events
� Historically
� Krakatoa in 1883
� Mount Tambora in 1815 which led to “a year without
summer”
� But ….. Western half of La Palma could slide causing
Tsunami of initial height of 1,000m at island to 50m at
Caribbean and Eastern North America
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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IMPACT EVENTS
� Risk comes from asteroid belt which lies between planets
Mars and Jupiter
� Now constant monitoring by NASA Near-Earth Object
Programme Office
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IMPACT EVENTS� 2008 TC3 exploded 23 miles above Nubian desert on 7th
October 2008
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IMPACT EVENTS� Chelyabinsk meteorite airburst on 15th February 2013
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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(SUPER)NOVA OR GAMMA RAY
� Gamma rays are beyond the X-ray spectrum
� Cause damage similar to radioactivity
� At the very least, sunspot activity can disrupt satellites
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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GEOMAGNETIC REVERSAL� A change in earth’s magnetic fields such that the
positions of magnetic north and magnetic south are
interchanged.
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GEOMAGNETIC REVERSAL
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SOUTH ATLANTIC ANOMALY
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SOUTH ATLANTIC ANOMALY
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SOUTH ATLANTIC ANOMALY� Increased flux of energy particles dipping to altitude of
200 km
� Exposes orbiting satellites to higher than usual radiation
� International Space Station requires extra shielding
� Hubble Space Telescope does not take observations while
passing through the SAA
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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ICE AGE CYCLES� New data on inter-glacial periods
� Would expect to be in another ice age
� 7,000 years ago an ice cycle should have started
� When planet should have been getting cooler, temperatures started to increase
� Why?
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ICE AGE CYCLES� 12,000 years ago there was an extensive ice sheet over the
northern hemisphere (water locked in as ice)
� 11,000 years ago, farming started in “the fertile crescent”
� CO₂ release from burning trees to clear land & CH₄ release from domestic animals
� Impact was that there was an increased desertification in the “fertile crescent”
� Water supply became extremely important
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GLOBAL WARMING� GREENHOUSE GASES
� CO₂ and CH₄ both trap radiation and lead to global warming
� CH₄’s lifetime in the atmosphere is much shorter than CO2
� CH4 is more efficient at trapping radiation than CO2.
� Pound for pound, the comparative impact of CH4 on climate
change is more than 25 times greater than CO2 over a 100-
year period.
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GLOBAL WARMING� Focus has previously been on CO₂
� 2015 United Nations Climate Change Conference
� Agreed to 2% increase in global emissions
� Wish to pursue efforts to limit the temperature increase to
1.5%
� The 1.5% goal requires zero emissions sometime between
2030 and 2050
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GLOBAL WARMING
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GLOBAL WARMING & OCEANS� Even if the world manages to limit global warming to 2°C sea levels
may rise by 6 metres (20 feet)
� Ice sheets are being warmed from above and below
� Once the ice sheets start to melt, the changes become irreversible
� The British Antarctic Survey Station will have to be moved as a huge crack has appeared in the ice sheet
� The I Newspaper on 11th May 2016 reported that 5 Pacific Islands have disappeared
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SEAL LEVEL INCREASES
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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METHANE RELEASE
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METHANE RELEASE
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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H₂S EMISSIONS FROM SEAS� Namibian coast has most intense upwelling of fertile deep-
ocean water
� H₂S Release due to seafloor organic sediments rich in organic
matter
� Late February 2012
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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ANOXIC EFFECTS� When water becomes saturated with carbon there is a
rise in atmospheric carbon
� This causes a positive feedback loop
� The result is a runaway greenhouse effect
� Increased ocean acidity = survival problems for
phytoplankton which use carbon and release oxygen
� Decrease in atmospheric oxygen
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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OCEANIC OVER TURN� Ocean currents & wind patterns
� Ocean currents circulate water throughout the world’s
oceans
� Global warming means more fresh water is released into
higher latitudes where deep water is formed
� This reduces the density of surface water
� Water sinks more slowly than it normally would
� Slower ocean currents = fewer nutrients = damage to
marine ecosystem
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OCEANIC OVER TURN
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OCEANIC OVER TURN� Weather
� Put simply, colder regions would get warmer and
warmer regions would get colder
� Impact on jet stream patterns
� El Niňo
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CAUSES� Plate tectonic movement
� Massive volcanism
� Impact events
� A nearby nova, supernova or gamma ray burst
� Geomagnetic reversal
� Sustained and significant global cooling
� Sea-level falls
� Sustained and significant global warming
� Methane release from continental shelves
� Hydrogen sulphide emissions from seas
� Anoxic events
� Oceanic over-turn
� Water cycle
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WATER CYCLE� 2,000 years ago, we intercepted the water cycle
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WATER CYCLE� Vast quantities of water are diverted into dams and
irrigation channels for farming and human consumption
� Los Angeles network of aqueducts, canals and pipelines deliver 90% H₂O
� 5x as much fresh water is stored in reservoirs than flows in the world’s rivers
� If we are to survive, our water usage must change
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HOLOCENE EXTINCTION
� Dates from 10,000 years ago to the present day.
� It covers the period since the ice retreated after the last
glaciation and it is sometimes regarded as just another
interglacial period
� Humans are driving this extinction event
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IS IT TOO LATE?
� 2015 United Nations Climate Change Conference
� Agreed to 2% increase in global emissions
� Wish to pursue efforts to limit the temperature increase to
1.5%
� The 1.5% goal requires zero emissions sometime between
2030 and 2050
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IS IT TOO LATE?� Limit world population
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IS IT TOO LATE?
� Change in agricultural methods
� Irrigation
� Crop rotation
� Widespread acceptance of GM foods
� Eat less meat
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IS IT TOO LATE?� Carbon capture
� Algae capturing CO₂
� Artificial trees to capture CO₂
� Plans to use sandstone to absorb CO₂
� Pump CO₂ through shale into sandstone
� Svalbard has the ideal geological structure
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IS IT TOO LATE?� National genebanks of seeds held as insurance
� Nordic Genebank held at an abandoned coalmine at Svalbard on Spitsbergen Island
� In 2008 became the Svalbard Global Seed Vault
� Stores duplicates of national genebanks
� Storing seeds is free to end users
� Norway and the Global Diversity Trust pays for operational costs – Bill & Melinda Gates Foundation
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IS IT TOO LATE?
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IS IT TOO LATE?
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IS IT TOO LATE?
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IS IT TOO LATE?� Seed vault is at a constant -18°C
� Deep enough to withstand a nuclear explosion
� Aims to store samples
� Every variety of seed
� From every stable crop
� From every country
� Genetic diversity paramount
� So far only one withdrawal request
� Syria in 2015
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OTHER FACTORS TO CONSIDER
� Antibiotic resistance
� Global financial cost of taking no action will be the loss of 10 million lives a year and £69 trillion a year by 2050
� New viral infections
� Zika virus causes microcephaly
� WHO predicts that 18 European countries at moderate risk in 2016
� Highest risk – Madeira, Black Sea coast of Russia & Georgia
� Political “hot potato” due to mass migration resulting from food shortages
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