Chapter 24 Human awareness

1. Chapter 24Human awareness E10 Human PRACTICES CAN LEAD TO MAJOR CHANGES IN COMMUNITIES

2. E10.1 Give examples of species’ extinction that have been brought about by human activities • Extinct- no longer found in the wild and not seen for many years (~ 50) • Extinction is normal to a degree- current loss is greater than ever before • Australia has suffered its greatest loss in 50 years • Read quote pg. 222/225 LB- in which destruction of habitat is listed as the major cause of extinction

3. EVERY HOUR…. (HUMAN ACTIVITY) • Around 8 species become extinct around the world • 10,000 times the normal extinction rate • Of 144 marsupials, 10 HAVE BECOME EXTINCT and 19 endangered in Australia since the 18th century • European settlement-species that require large areas have died out (Tasmanian Tiger) • Some animals restricted to small areas- died out • Those with specialised habitat needs- died out (Rufus Hare Wallaby) • Some rare habitats cleared for agriculture and pasture or urban settlement- more species extinct

4. Human aCtivity • Human activity has impacted species survival in a number of ways…most of which you will know Climate change Harvesting Habitat clearance Pollution Introduced species Mining SPECIES DIVERSITY

5. Introduced species • Many species been introduced since European settlement • They compete with natural species for resources • Or feed on those species • Cats, dogs, foxes, carp, rabbits, pigs donkeys, goats, cane toads, sparrows, starlings, trout and salmon • Cats were introduced to control mice and rats??? Successful?

6. Cont: • 1850- established populations of feral cats in the wild- eat small mammals, birds and reptiles • Rabbits used to be their food which was helpful/kept a balance/ but with the Myxoma viruses etc. less rabbits so more native species being targeted • Rabbits were introduced in 1859- destroyed much vegetation/compete for resources/take over native animal burrows like the bilby’s and bandicoots • Feral pigs damage the habitat as they wallow at swamp edges and destroy vegetation

7. Herbivores • Large herbivores like Kangaroos have evolved in the nutrient poor ecosystems and exert little pressure ion the environment • Its introduced species like goats that stress the fragile environment • INTRODUCED PLANTS • CAN BE A MAJOR ECOLOGICAL PROBLEM-overtaking native species, poisonous to other species, competes with native vegetation , difficult to remove, chokes waterways • See table page 223 or 226 LB

8. POLLUTION • HUMAN LIFESTYLE HAS DIRECTLY CREATED A POLLUITON PROBLEM • Pesticides/insecticides-DDT accumulated in tissues, interferes with calcium metabolism in birds causing eggs to be produced which break • Oil tankers- spillage/fish and aquatic life dies

9. Acid Rain • Accumulation of sulfur and nitrogen oxides form burning fossils fuels • These chemicals react with water vapour-sulfuric acid and nitric acid • Rain fall then erodes buildings, changes pH of lakes and waterways poisons aquatic life • Human respiratory issues

10. CFC’s • Chlorofluorocarbons • Widely used in aerosol sprays and refrigerants- react with the chemical ozone • Significant destruction of ozone in the upper regions of the Earth’s atmosphere – led to ozone hole over Antarctica • Ozone provides life on earth with protection form UV rays

11. Heavy metal poison/sewage • Industry-produces heavy metal pollutants-mercury, cadmium and arsenic • These kill soil organisms and disrupt marine ecosystems • Stormwater drains into the oceans taking with it a cocktail of oil, fertilizers and many other chemicals • Sewage: • Organic wastes for untreated sewage/intensive animal farming can lead to pollution of the waterways • Nitrates/phosphates choke lakes and rivers with excess algae growth and damage marine ecosystems

12. Fertilisers/detergents • Run off with fertilisers and detergents headed into lakes and rivers leads to excess algae growth • Stifles waterways • Destroys other forms of life • Nitrates and phosphate- essential for healthy growth BUT in EXCESS destroys • Eutrophication-occurs with excess nutrients like nitrates • Excludes all growth except bacteria in the waterways

13. Radioactive wastes • Chernobyl nuclear incident-Ukraine 1986 • Explosion occurred due to a nuclear reactor blowing up-plume 5 km high • Radioactive wastes travelled across Europe form Scandinavia to Greece • 70,000 deaths plus over time • Poisons found in Lichens, animals fed on them- 100km form the explosion site

14. Australia-and nuclear waste • The outback has been identified as a suitable dumping ground • Much debate has ensued • Our high cost of living/lifestyle comes with a greater cost- wastes that must be dealt with • And we must minimise damage to the environment in the process of disposal

15. mining • Mining removes vegetation and topsoils • Disrupts ecosystems • Pollutants and minerals bought to the surface • These end up in run off in rivers etc. • Some companies engage in re-vegetation • Need to preserve native flora

16. Climate change • By product of combustion- carbon dioxide in the air • Atmospheric carbon dioxide increasing • Traps the heat in the atmosphere • Increases global temperatures- green house effect • Temperatures expected to rise 3-4 degrees in future (75 years) • Polar ice melting, expansion of sea water, rise in sea levels, terrestrial habitats altered • Species move to their preferred habitats

17. harvesting • Industry harvests natural resources • Fishing • Can be sustainable if managed well • Trawling/dredging kills huge numbers of other species though- NOT HELPFUL

18. HABITAT CLEARANCE • Extensive rainforests are destroyed to support economies- South America, South-East Asia and Central Africa • Natural habitat destroyed, forests, vital for absorbing Carbon dioxide also destroyed • Similar destruction occurred in last 200 years in Australia • Read ex: page 227/230 Toolache wallaby……

19. E10.2 Explain why the best way to preserve species is to preserve habitat • Habitat destruction main cause of extinction and endangerment of species • Austrlai has a very high rate of native vegetation clearance • See table page 228/231 • Estimated 5 million hectares cleared between 1983-1993 • Destroys native species habitat/them and diversity is greatly reduced

20. Reasons to maintain natural vegetation: • Provide a range of habitats to maintain species diversity • Provide vegetation with deep roots to maintain the water table and prevent salinity • Maintain and protect soil form erosion • Absorb carbon dioxide and produce oxygen • Maintain regional rainfall patterns • Reduce weeds and feral animals

21. Temperate wood lands • Most threatened • 80 % have been cleared • High number of threatened species • Birds particularly impacted • Destroys nesting sites-chain reaction • Loss of food sources- and destruction can create a succession environment- opportunistic species then can be weeds, and feral organisms that further destroy the environment- breaking down the woodland environment • Further loss of species diversity…. Read page 229/232

22. E11 THE LEVEL OF HUMAN POPULATION IS A BIOLOGICAL AND ETHICAL ISSUE • E11.1 Explain how the growth of the human population is placing huge demands on the resources of the biosphere • Homo sapiens evolved on the planet 1 million years ago • Current population over 6 billion • This places a huge strain on the earths resources • Developed countries energy consumed per person is 20-30 times more than someone in a developing country • As our standard of living improves the demand for resources increases

23. Fossil fuels e11 • Our demands for energy have been met using fossil fuels- a finite resource (coal, gas and oil) • Scientists have been working to develop alternative fuel sources like Sun/wind and nuclear power • Nuclear power as we know has other huge potential issues • Solar and wind hold huge promise- but need technology to advance to harness it the full potential

24. Soil/land availability • Huge number of humans means huge demand for land to live on plus to farm on • Nearly all land than be cultivated is being used • Some land not productive long term • Mineral content of the land depleted/eroded • Poor quality fruit and veg being produced as a result • To feed more people need to be a continuation of ecologically sustainable farming • New wheat and rice varieties have been developed to increase yields • We need to double food production over the next 40 years to sustain the population growth worl wide

25. water • Water important resource • Essential for survival- yet many in the world have difficulty accessing fresh water supplies • 3.4 billion people use around 50 litres of a water a day-Australians use 250-300 litres a day- way over the world average • Three children die in India every minute form disease carried in polluted water • Water is a disappearing resource

26. biodiversity • Most important resource for humans being placed at risk is the biodiversity of animals and plants on the biosphere • estimated that 20% of the world’s biodiversity may be lost during the next 30 years • Organisms offer food, medicine, new drugs, clothing and help recycle the matter and energy in ecosystems- a loss of this has been discussed and has devastating effects on life.

27. E11.2 explain why the exponential growth of the human population is not sustainable • For 99 % of human history- no growth essentially • Last 1 % human numbers have increased exponentially- China and India having 40% of the worlds population • Usually the size of a population remains constant- birth and death equal out • populations reach a carrying capacity • CYCLE IS- numbers grow as reproductive capacity grows and resources are readily available-then competition increases, resources diminish, predators and disease keep numbers in check, wastes accumulate- population size stabilises or reaches its carrying capacity

28. Human population • Human population followed exponential growth • Expanding the carrying capacity with increasing technological development- agriculture and medicine • There must be a slowing in the rate of increase in the human population • Our demands on the biosphere have been discussed- its not sustainable

29. Final comments!!! • It may seem doom and gloom… • The planet is overpopulated and we are heading toward extinction… • We have the ability to change our course of action though.. • We have had a slowing of the human population growth since the 1960’s • contraception has been very helpful- especially in developing countries • Environmentalists and the “green movements” have been heard and govts. have started to employ practices that work more harmoniously with the environment • Scientist continue to search for ways to improve farming practices, increase yields, reduce the use of pesticides and insecticides etc. • The third millennium our biggest challenges …what will you do to help??? • Ok you’re all done!!!! Happy revision 