Human Influences

• In the last 100 years the human population has exploded!
• Exponential growth


  The rapid increase in human population
• Effects of human population explosion

  • Shortage of food in some countries
  • More land used for building and farming
  • More pollution produced
  • The world's resources are running out
  • It's not sustainable
• Global warming is one of the biggest issues currently facing the planet
• Greenhouse effect


  The sun releases short wave radiation, some of which is readmitted as long wave radiation, and this is absorbed and trapped by greenhouse gases in the Earth's atmosphere, heating up the Earth
• Greenhouse gases


  • Water vapour
  • Carbon dioxide
  • Nitrous oxide
  • Methane
  • CFCs
• Greenhouse gases


  • We need to trap some radiated heat in the atmosphere otherwise we would freeze
  • The quantity of greenhouse gases in the atmosphere has increased drastically due to human activity and it is trapping too much heat
• Humans have massively increased the level of CO2 in the atmosphere by burning fossil fuels in factories, power stations, houses and vehicles
• There is a lot more cattle on the planet to feed the growing population and they all produce methane as a waste product of digestion
• Methane is also released from the decay in landfill which is increasing
• The increase in rice production causes more methane due to the bacteria that live there
• CFCs are mostly banned now due to them destroying the ozone layer which ends up letting more UV light in
• Car fumes contain nitrous oxide although catalytic converters reduce this
• The use of fertilisers increases nitrous oxide because the nitrates are converted to nitrous oxide by denitrifying bacteria
• Human activity has not really influenced the level of water vapour in the atmosphere
• Effects of global warming

  • It would change the nature of many ecosystems potentially causing species to become extinct
  • Polar ice caps would melt causing sea levels to rise
  • A change in the major ocean currents could occur
  • A change in global weather patterns
• Carbon monoxide


  Colourless, odourless and tasteless gas formed when petrol and diesel are burned in combustion engines, which binds to haemoglobin instead of oxygen causing suffocation and death
• Sulphur dioxide is released by burning fossil fuels
• Acid rain


  Sulphur dioxide dissolves in rainwater to make sulphuric acid, which acidifies water in lakes and kills many plants and animals sensitive to pH, and damages trees by killing leaves and releasing toxic substances from the soil
• Untreated sewage from humans, nitrates from fertilisers used by farms and pesticides have all caused damage to water systems
• Eutrophication


  Water in streams and rivers can become polluted with nitrates and phosphates from fertilisers that have leached from farmland, and from sewage containing phosphates from detergents and nitrates from urine and faeces, causing rapid growth of algae, depletion of oxygen, and death of other organisms
• Consequences of deforestation


  • Less evapotranspiration, leading to drier local climate
  • Leaching, leading to infertile soil
  • Soil erosion, as there are no tree roots holding the soil in place
  • More carbon dioxide and less oxygen, as the trees that used to remove CO2 and produce oxygen have been removed
• Water vapour is not a greenhouse gas
• Atmospheric CO2 levels have increased due to humans
• Nitrous oxide levels have increased due to aerosols
• Global warming can cause sea levels to rise
• Carbon monoxide binds to haemoglobin
• Carbon monoxide does not cause acid rain
• Acid rain does not change hair colour
• Eutrophication is not caused by excess sodium
• Deforestation causes soil erosion
• Deforestation removes CO2 from the atmosphere
• Suggestions to reduce effects of deforestation

  • Recycling/use recycled products
  • Plant more trees
  • Use less paper
  • Manage forests sustainably
  • Eat a plant based diet
  • Improve education
  • Change legislation