Flashcards in Human Population Deck (21)
At what century did human poplation take off and why?
The 17th century - increased global communication, increased technological development
Since the 17th century how has human population grown?
What did Malthus state in his essay in 1798?
That humans are increasing exponentially while food is increasing arithmetically which will eventually lead to poverty, starvation, crimes and wars.
Malthus suggested that society should regulate it's reproductive output
What did Karl Marx state population growth was caused by in 1840?
Believed that population growth is caused by poverty which is caused by oppression and exploitation
He believed social justice was the solution
What idea does evidence support nowadays, Marx or Malthus?
Marx - food supplies have grown faster than the planets population
- famines occur for socioeconomic reasons not a lack of food
- technology has permitted larger populations
- 80% of the worlds population lives in areas characterised by poverty, youth and rapid growth, the other 20% is rich, ageing and has low or zero growth
Describe the three stages of the demographic transition?
Pre modern - food shortages, no sanitation, poverty etc = high birth rate and death rates (stable population) eg Zimbabwe and North Korea
Transition. - economic development, improved food supplies, sanitation etc = high birth rates and low death rates (population expands) eg India and China
Mature economy - low birth and death rates (stable population) eg EU and USA
What stat needs to drop first before birth rates will drop?
What impacts do humans have on the environment?
Habitats and species destruction
Waste production and disposal
How many species are estimated to be lost per decade?
How much rainforest is lost per year?
Over 1000 a decade
10 million hectares per year
Why should species loss matter?
Sources of food
Over 50% of prescriptions contain natural products
Ecological functions (decomposition, nutrient cycling etc)
Cultural benefits (fishing, camping, hiking etc)
Types of chemical pollution caused by humans?
Nutrients (esp. Nitrates)
Metals (Mercury, lead etc) often bioaccumulate
Pesticides (DDT), dioxins - usually leaks from landfills
Types of air pollution?
Sulphur dioxide, CO2, NO, VOC's, lead, ozone, particulates
How does sulphur dioxide effect the environment?
Da,ages plants and animals
Mostly from industry
Can form sulphuric acid by dissolving in water vapour (acid rain)
How does carbon monoxide effect the environment?
Very toxic gas, mostly from transportation (77%)
Inhibits respiration by binding to haemoglobin
In atmosphere can react to form ozone
How do nitrous oxides effect the environment?
From power plants and transportation (50/50)
Form nitric acid by reacting with water vapour - damages plants/buildings/watercourses etc
Causes lung damage, aggravates asthma, bronchitis etc
How do volatile organic compounds effect the environment?
From plants, bogs and animals
Includes various terpenes , methane, phenols
Can form photochemical smogs, many are a health risk
How does lead effect the environment?
Released mostly by industry (mining, ore smelting, leaked petrol)
Primarily damaging to children in urban areas
Effects of particulates in the environment?
Dust from soil erosion, mining, rock crushing
Can be health hazard
Form smog in urban areas
Effect of ozone in environment?
Important in the stratosphere as this has blocks harmful uv Rays
In ambient air however ozone damages animals, plants and buildings - lung irritation etc
Formed as a result of VOC's and CO reacting further upon exposure to sunlight
Points about human water usage?
Essential for life, 75% of planet is covered in water
Hydrological cycle driven by solar energy
Use of water has increased twice as fast as population growth in the last century and could be a source of hostility
70% is used in agriculture
Increasing population will stretch this resource further