2016-06 Mass extinction SS - u3asites.org.uk€¦ · MASS EXTINCTION LATE DEVONIAN EVENT 375-360 MA Killed off 19% of all families 50% of all genera 70% of all species 6. MASS EXTINCTION

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



� 70% of all species

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MASS EXTINCTION

� PERMIAN-TRIASSIC EVENT

� 252 MA

� Killed off




� Ranked largest of five extinction events

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MASS EXTINCTION

� TRIASSIC-JURASSIC EVENT

� 201MA

� Killed off 23% of all families



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MASS EXTINCTION

� CRETACEOUS-PALEOGENE EVENT

� 66MA

� Killed off� 17% of all families


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� Water cycle

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METHANE RELEASE

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METHANE RELEASE

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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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� Impact events




� Sea-level falls




� Anoxic events


� 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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Documents

2016-06 Mass extinction SS - u3asites.org.uk€¦ · MASS EXTINCTION LATE DEVONIAN EVENT 375-360 MA Killed off 19% of all families 50% of all genera 70% of all species 6. MASS EXTINCTION