MASS EXTINCTION. Halesworth & District

Transcription

1 MASS EXTINCTION Halesworth & District 1

2 Signs indicate an imminent 6 th Mass Extinction and this time Humans are the cause 2

3 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 3

4 MASS EXTINCTION 4

5 MASS EXTINCTION ORDOVICIAN-SILURIAN EVENTS 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 5

6 MASS EXTINCTION LATE DEVONIAN EVENT MA Killed off 19% of all families 50% of all genera 70% of all species 6

7 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 7

8 MASS EXTINCTION TRIASSIC-JURASSIC EVENT 201MA Killed off 23% of all families 48% of all genera 70-75% of all species 8

9 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 9

10 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 million years after a severe mass extinction event 10

11 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 11

12 PLATE TECTONIC MOVEMENT Very slow process Ocean floor spreading Some earthquake faults very weak 12

13 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 13

14 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 14

15 IMPACT EVENTS Risk comes from asteroid belt which lies between planets Mars and Jupiter Now constant monitoring by NASA Near-Earth Object Programme Office 15

16 IMPACT EVENTS 2008 TC3 exploded 23 miles above Nubian desert on 7 th October

17 IMPACT EVENTS Chelyabinsk meteorite airburst on 15 th February

18 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 18

19 (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 19

20 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 20

21 GEOMAGNETIC REVERSAL A change in earth s magnetic fields such that the positions of magnetic north and magnetic south are interchanged. 21

22 GEOMAGNETIC REVERSAL 22

23 SOUTH ATLANTIC ANOMALY 23

24 SOUTH ATLANTIC ANOMALY 24

25 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 25

26 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 26

27 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? 27

28 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 28

29 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 CO 2 CH 4 is more efficient at trapping radiation than CO 2. Pound for pound, the comparative impact of CH 4 on climate change is more than 25 times greater than CO 2 over a 100- year period. 29

30 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

31 GLOBAL WARMING 31

32 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 11 th May 2016 reported that 5 Pacific Islands have disappeared 32

33 SEAL LEVEL INCREASES 33

34 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 34

35 METHANE RELEASE 35

36 METHANE RELEASE 36

37 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 37

38 H₂S EMISSIONS FROM SEAS Namibian coast has most intense upwelling of fertile deepocean water H₂S Release due to seafloor organic sediments rich in organic matter Late February

39 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 39

40 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 40

41 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 41

42 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 42

43 OCEANIC OVER TURN 43

44 Weather OCEANIC OVER TURN Put simply, colder regions would get warmer and warmer regions would get colder Impact on jet stream patterns El Niňo 44

45 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 45

46 WATER CYCLE 2,000 years ago, we intercepted the water cycle 46

47 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 47

48 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 48

49 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

50 Limit world population IS IT TOO LATE? 50

51 IS IT TOO LATE? Change in agricultural methods Irrigation Crop rotation Widespread acceptance of GM foods Eat less meat 51

52 Carbon capture IS IT TOO LATE? 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 52

53 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 53

54 IS IT TOO LATE? 54

55 IS IT TOO LATE? 55

56 IS IT TOO LATE? 56

57 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

58 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 58