Population and the Environment Flashcards
what is the size of the population in an area influenced by?
how many people the environment of that area can support
what is population distribution?
the pattern of where people live
what is population density?
the population of an area divided by the size of that area
when did the worlds population reach 1 billion?
1804
what prevented the population from growing rapidly before 1800?
famine, disease and war
what has increased life expectancy and reduced infant mortality rates?
medicine and food production
what is the population predicted to reach by 2050?
9 billion
how has the distribution of populations changed?
globally, urban populations are increasing faster than rural ones
why are populations becoming less evenly distributed?
urban populations are increasing faster than rural ones
what are the three main aspects of the physical environment that affect populations?
- climate
- soils
- resource distribution
how does climate type affect the global distribution of population?
- few people live in arid areas, but many live in temperate areas
- tropical and temperate climates usually have the highest population densities because its easier to produce food
how is climate change affecting population distribution?
- in coastal areas where sea levels are rising, people are moving inland
- causing levels of nutrition to fall in some developing countries
how does soil fertility affect populations?
soil fertility determines the amount and type of food that can be produced in a region
how can soil erosion affect populations?
it can cause people to migrate to other places as agriculture becomes more difficult
how does climate affect populations?
- climate type affects the global distribution of people
- climate change affect population distribution
how does soil affect populations?
- soil fertility determines the amount and type of food that can be produced in a region
- played a role in where human settlements have developed and the size of populations
- soil erosion can cause people to migrate to other places as agriculture becomes more difficult
why has food production increased globally over the last 50 years?
- the area of land used to produce food has increased
- technological advances
why does East Asia and North America produce a lot of food?
- climates that are good for farming
- lots of investment in farming
why does Central America and Africa produce relatively small amounts of food?
- lack of resources and funding for farming equipment
- large areas of land that are unsuitable for farming as they are either mountainous, or they have poor quality or little soil
- unsuitable climates - some areas don’t get enough rainfall or are too hot
why is there a need for more food?
- the global population is increasing
- food consumption per person is increasing
how can resource distribution affect populations?
- population growth and distribution are linked to the availability of fresh water and other natural resources
- lack of safe water can lead to food insecurity, health problems, and death (can cause populations to decrease)
- places with naturally occurring food and fueler able to support fairly large productions
- energy and mineral resources can cause local concentrations of people
what is agricultural productivity?
a measure of the amount of food that is produced in a n area (its the ratio of agricultural output)
what is commercial farming?
the production of crops or livestock to make a profit
what is subsistence farming?
when just enough food is grown to feed the family
what is intensive farming?
as much as possible is produced from the land
what is extensive farming?
has low capital and labour input for the area of lands produces less food than intensive farming
what is nomadic farming?
farmers move from place to place to grow crops of graze animals on different land
are farms open or closed systems?
open
why is global good consumption unevenly distributed?
- the global population is increasing, so more food is being consumed
- food consumption per person is increasing the world becomes more economically developed
- food consumption varies between countries
- types of food consumed vary between countries at different levels of development
why can more developed countries consume a lot of food?
- they can afford to import a large variety of foods
- a culture of consumerism
- high disposable incomes, so can afford more food
why can less developed countries consume less food?
-they can’t afford as much food
why are emerging economies starting to consume more?
the wealth is increasing
in an open system what can be gained or lost from the environment?
energy and matter
what are some natural inputs to farmland?
solar energy and rainwater
what are some human inputs to farmland?
seeds and fertilisers
what is the main output of farms?
food
what re energy and matter transferred to and stored in?
soil, crops and/or animals
how is agricultural productivity affected by commercial farming?
it has high agricultural productivity and is more common in developed countries than developing countries
how is agricultural productivity affected by subsistence farming?
lower agricultural productivity
what is capital intensive farming?
farming has a high input of capital and a low input of labour for the area of land. involves using fertilisers, pesticides and labour saving machinery
what is labour intensive farming?
farming doesn’t involve much capital but uses a lot of labour
what are the two ways the physical environment is affected by agricultural productivity?
- climate
- soil
how does soil affect agricultural productivity?
- some areas are unsuitable for farming because there is not enough soil or the soil quality is poor
- different types of soil are suited to different types of farming
how does climate affect agricultural productivity?
- some climates make farming more difficult
- some crops are adapted to particular climatic conditions
- the climate affects how successfully plants can grow in an area and the animals that can survive there
what are the five climatic zones?
- arid
- continental
- polar
- temperate
- tropical
why are population sizes and lifestyles in different climatic zones often different?
climate affects things like agricultural productivity and water availability
polar climates are mainly found above what latitude in the northern and Southern Hemisphere?
66* latitude
how does the precipitation usually occur in polar regions?
as snow
what are the temperatures in the winter in polar regions?
often below -40*c
what are the temperatures in the summer in polar regions?
range from about -10c to +10c
what is the precipitation in mm per year in polar regions?
100mm per year
what is the precipitation in mm per year in the interior of Antartica?
less that 50mm per year
what are the temperatures in Antartica in the winter?
below -80*c
what are the two main types of polar climate environments?
- ice caps
- tundra
what are ice caps as polar climate environments?
layers of ice permanently covering an area
what is tundra in polar climates?
permanently frozen ground called permafrost
what is the population of the Arctic?
around 4 million
what affects traditional lifestyles in the Arctic?
- low temperatures
- low precipitation
why is arable farming not generally possible in the Arctic?
few plants can survive the temperatures and the ground is often frozen solid
agricultural productivity is low, so what are traditional lifestyle based onion the Arctic?
subsistence farming (produce enough food for yourself, but not enough to trade)
how does food cause some native people to migrate seasonally?
many of the species Artic people eat, leave the most extreme environments in winter, so they migrate to be closer to a food source all year round
how have Arctic people adapted to the cold temperatures?
with clothes and building methods that provide insulation
how does the climate affect development in polar regions?
- low temperatures and frozen ground make it hard for people to work and construct buildings, so development is difficult
- seasonal work - tourism summer and gas and oil reserves are all in summer, creating more jobs
- melting of Artic sea ice in summer opens up shipping routes, making trade easier, and commercial fishing is able to take place
how many mm of rainfall do arid areas get per year?
usually less than 250mm
where do hot deserts occur around the equator?
30* north and south of the equator
what is the maximum air temperatures of hot deserts?
above 40*c
how has climate change impacted agriculture?
- decreasing agricultural productivity in some areas
- increasing agricultural productivity in some areas
- changes in types of crops grown
- agricultural pests and diseases may increase in some areas
why is distribution uneven in arid areas?
there are clusters of settlements around water sources and other areas are left uninhabited
why is agriculture impossible in most arid areas?
rain only falls very infrequently, usually in heavy convectional rainstorms which can cause flash flooding and soil erosion
how does a dry climate affect traditional lifestyles?
- agriculture is impossible due to lack of rainfall
- water can be drawn from oases to irrigate nearby crops
- other native people are nomadic, allowing people to keep grazing livestock despite the sparse vegetation
what are the modern solutions to the challenges of arid climates?
- groundwater for irrigation can be more easily accessed with motorised pumps (e.g. drip irrigation)
- economic development is often hindered by the climate, but major cities can develop if there is enough money to invest in obtaining water
what is soil formed from?
a combination of minerals from weathered bedrock and organic matter from vegetation
soil is the material between what?
ground surface and the bedrock
what are zonal soils?
mature soils that have developed from the interaction between climate, vegetation and parent rock between a significant period of time
how can soil types be identified?
by looking at the distinct layers in the soil profile, which are known as soil horizons
where do podzols occur?
in cool temperate climates in the northern hemisphere, where there is more precipitation than evapotranspiration
where are podzols usually found?
under coniferous woodland or heather moorland
what is the O horizon?
a layer of needles from the coniferous trees or heather leaf litter, and below this is a narrow, acidic A horizon
what is leaching?
when water moves mineral and nutrients down through the side profile
why are podzols acidic?
the leaf litter from coniferous trees and heather is acidic, and they often form on acidic sandstone or clays
because podzols are acidic, what will happen to the water traveling through the soil?
it is more able to dissolve certain minerals such as iron and aluminium compounds
are podzols good for agriculture?
no
why is arable farming difficult in podzols?
- the acidity and lack of nutrients means that few crops are able to grow
- formation of a hard pan can prevent water draining away, making the soil vulnerable to water-logging, damaging crops. water-logging also makes ploughing difficult
what is required for arable farming to take place on podzol?
it requires treatment with lime to reduce acidity, and extensive artificial fertilisation
where are latosols found?
under tropical rainforests
what is water logging?
when the space between soil particles fill up with water
what are the causes of water logging?
- soil with few airspaces fill up with water quickly
- ‘hard pans’ or paternities hinder drainage, which can cause water logging of the soil above
- precipitation is higher than evapotranspiration
- too much irrigation
what problems does water logging cause for agriculture?
- plant roots are surrounded by water, which limits their growth and can rot them
- water decreases soil temperature which can reduce crop growth
- crops may be out competed by weeds that can cope better with the wet conditions
- land is hard to plough
what are the management strategies for water logging?
- avoid overwatering crops
- drain the soil using underground pipes or ditches around the fields
- change the composition of the soil
what is salinisation?
the build up of salts in the soil
what causes salinisation?
- high temperatures draw water to the surface where it evaporates, leaving behind salts
- in dry climates there isn’t enough rainfall to leach salts away
- irrigation water contains salts, so when the water is absorbed by plants, the salts are left behind
- some fertilisers contain salt
what problems does salinisation cause for agriculture?
- salt can stop crops from absorbvingthe water they need from the soil
- some salts are toxic to plants
- water flows from areas of low to high salinity. High soil salinity means water may flow from plant roots to the soil, dehydrating plants
what are the management strategies for salinisation?
- avoid water logging
- only use as much water for irrigation as is needed
- add the appropriate amount and type of fertiliser
what is structural deterioration?
when the pore spaces in the soil are lost
what are the causes of structural deterioration?
- use of heavy machinery, or trampling by livestock or people, can compact soil
- removal of vegetation, plant roots help maintain soil structure
- salinisation in clay soils, as salt causes clay particles to clump together
what problems does structural deterioration cause for agriculture?
- if the soil is too compacted, its difficult for plant roots to grow
- a loss of pore spaces in the soil means that there is a reduced capacity for water, so plants can dry out
- land is hard to plough
what are the management strategies for structural deterioration?
- avoid compaction by moving livestock regularly
- maintain vegetation cover
- avoid salinisation
- change the structure of soil by adding sand to clay soils
when do people have food security?
when they have enough nutritious food
what does food security depend on?
- food availability
- food access
- food quality and use
what must there be for food availability?
a country must produce and/or import a sufficient amount of food
what must there be for food access?
people must be able to regularly obtain food
what must there be for food quality and use?
the food that people consume must be nutritious enough for them to maintain a healthy life. It must be stored and prepared in a way that is safe and hygienic
how can food security be increased?
by producing more food, sharing it out evenly and reducing the amount wasted
how can food production be increased?
- agricultural expansion
- intensive farming
- changing the types of food produced
- technology
how can agricultural expansion increase food production?
more land can be converted to agricultural use
what is the disadvantage of agricultural expansion?
it destroys ecosystems
how can intensive farming increase food production?
it increases as much food as possible from the land available.
how can changing the types of food produced increase food production?
producing plants needs less land and water than producing meat and dairy, so converting to arable farming means more food can be produced
how can technology technology increase food production?
- crops can be genetically modified to produce higher yields or to resist pests and diseases
- limits need for artificial pesticides
- hydroponics mean crops can be grown in places where there’s a lack of fertile soil
how can food access be increased?
- trade
- improve access to markets
- aid
how can trade increase food access?
food can be imported to countries that don’t have enough
how can waste be reduced?
- production
- distribution
- consumption
how can production reduce waste?
crop loss due to pests and disease can be decreased by educating farmers on prevention and providing them with better resources
how can distribution reduce waste?
many shops discard food that they don’t sell. Improving storage and packaging and spreading up the time it takes for food to reach consumers, increases shelf life. Some supermarkets donate food to food foodbanks
how can consumption reduce waste?
campaigns like ‘Think.Ear.Save’ encourage consumers to be less wasteful
how is health defined ?
physical, mental and social well being, and the absence of disease
what is health life expectancy?
the number of years a newborn child can expect to live in full health without major disease
where is health life expectancy the highest?
in more developed countries, e.g. UK, USA, Australia
where is health life expectancy the lowest?
in less developed countries, e.g. sub-Saharan Africa
what is mobility?
the rate of disease in a population
what are the two morbility indicators?
- prevalence
- incidence
what is prevalence as a morbidity indicator?
the total number of cases in a population at a particular time
what is incidences as a morbidity indicator?
the number of new cases in a population during a particular time period
what are the reasons for high morbidity of infectious disease in less developed countries?
- lack of clean water, sanitation and health care
- limited health education and overcrowded conditions in urban areas
can infectious diseases be passed between people?
yes
where is there high TB morbidity?
in less developed countries
where is there low TB morbidity?
in more developed countries
can non communicable diseases be caught from someone else?
no
where is there high breast cancer morbidity?
in more developed countries
where is there low breast cancer morbidity?
in less developed countries
why is there high morbidity of non communicable diseases in more developed countries?
- higher proportion of old people
- unhealthy lifestyle
how does a higher proportion of older people cause high morbidity of non communicable diseases in more developed countries?
if there are more old people, more people are likely to suffer from diseases associated with old age
how does unhealthy lifestyles cause high morbidity of non communicable diseases in more developed countries?
risk of some diseased increases if your overweight, eat unhealthy food or don’t do enough excercise
what does mortality mean?
death
what is high morbidity associated with?
mortality
what is mortality rate?
how many people die in a population over a period of time
what are mortality rates used to compare?
compare global patterns of death
what areas have a higher incidence rate of cancer?
more developed areas
where are mortality rates higher?
in more developed areas
where is the risk of dying from a disease higher?
in less developed countries
why is the risk of dying from a disease much higher in less developed countries?
- malnutrition
- poor access to health care
why does malnutrition cause more people to die from disease?
reduces the body ability to fight disease
why does poor access to healthy care cause people to die from disease?
people can’t access the drugs or other treatments they need to treat the disease
what does the epidemiological transition model state?
the main cause of mortality changes from infectious diseases to non communicable diseases over time
how many stages are in the epidemiological transition model?
the original model has 3 stages , but further stages have been suggested
what are the 4 stages of the epidemiological transition model?
- age of pestilence and famine
- age of receding pandemics
- age of degenerative and an made diseases
- delay of degenerative diseases
what does the epidemiological transition model suggest?
that countries move through the stages as they become more economically and socially developed
what is stage one of the epidemiological transition model?
age of pestilence and famine
-high number of deaths from infectious diseases (average life expectancy is low) (50 yrs)
what is stage two of the epidemiological transition model?
age of receding pandemics
-number of deaths from infectious diseases falls due to better living conditions and health care (average life expectancy starts to increase) (60 yrs)
what is stage three of the epidemiological transition model?
age of generative and man made disease
-non communicable diseases replace infectious diseases as the main cause of death (average life expectancy increases more) (70 yrs)
what is stage four of the epidemiological transition model?
delay of degenerative diseases
-non communicable diseases may be prevented on their onset delayed, and death rate reduced by better treatment (average life expectancy is high) (80 yrs)when
when do countries move through the stages of the epidemiological transition model?
as they become more economically and socially developed
why does malnutrition decrease as countries move through the epidemiological transition model?
because food availability increases, this increases the body ability to fight disease
what happens when countries develop through the epidemiological transition model?
- malnutrition decreases because food availability increases
- clean water becomes more widely available and sanitation improves, decreasing spread of disease
- better access to health care
- better health education
what can the stages of the epidemiological transition model be linked to?
the demographic transition model
is there ever a stage 5 of the epidemiological transition model?
some people think there is
what is stage 5 of the epidemiological transition model?
reemergence of infectious disease due to the evolution of antibiotics resistant bacteria, along with increasing travel and trade allowing disease to spread more easily
what are the environmental factors that can increase the risk of disease?
- climate
- topography
what are the climate factors that can increase the risk of disease?
- precipitation
- temperature
- extreme events
- seasonality
how does precipitation increase the risk of disease?
many disease vectors need water to survive so there are more infectious diseases in wetter climates. Higher than average rainfall can also cause growth in the population of disease vectors
how does temperature increase the risk of disease?
many disease vectors can only survive above a certain temperature threshold. This means that many infectious diseases occur only in tropical climates
how do extreme events increase the risk of disease?
- heavy rainfall can lead to flooding, causing sewage systems to overflow. This contaminates water supplies, making water borne diseases
- very low rainfall can lead to waterborne disease vectors becoming concentrated in water sources, making it more likely that people will become ill of they use the water
how does seasonality increase the risk of disease?
artic areas experience very little daylight during winter, and this can affect mental health
how does sunlight increase the risk of disease?
- lack of sunlight can result in vitamin D deficiency, which can lead to bone loss, kidney disease and intestinal problems
- over exposure to sunlight increases the risk of disease
what are the topography factors that can increase the risk of disease?
- drainage
- relief
- altitude
how can drainage increase the risk of disease?
- the flood plains of rivers tend to have high population densities. When they flood, drinking water can be contaminated, leading to the spread of waterborne diseases
- floods can force people to move, increasing pressure on resources
how can relief increase the risk of disease?
standing water collects at low points in the landscape, which provides a breeding ground for mosquitos carrying disease
how can altitude increase the risk of disease?
high altitudes can increase the risk of skin cancer because of increased exposure to ultraviolet rays
how can burning fossil fuels cause health problems?
long term exposure can cause respiratory problems as well as various cardiovascular diseases and types of cancer
how many deaths does urban air pollution cause every year?
around 1.2 million deaths
