Population and Environmental Consequences
Comprehension Objectives for Today’s Lecture
• The scope of human population growth
• The history of human population
• Fundamentals of demography
• The demographic transition
• Factors that affect population growth
• The effect of population, affluence and technology on the environment
• The current effects of disease in controlling population growth
Population: A root cause of environmental degradation?
• Much of the environmental degradation in the world is due to:
Wide misuse and overuse of resources by too many people.
• 1974: Paul Ehrlich and John Holdren
• Total impact (I) on environment is a result of the interaction between
population (P), affluence (A), technology (T), and sensitivity (S):
Population = individuals need space and resources
Affluence = greater per capita resource use
Technology = increased exploitation of resources or ways of better dealing with our
need for resources
Sensitivity = how sensitive an area is to human pressure
• Impact is largely POLLUTION, RESOURCE DEPLETION, or both.
The First Humans
• Oldest known homonid (human-like) fossils:
Ethiopia: 4.1 My. Bp
Chad: ~7 My. bp?
“Toumaï” Sahelanthropus tchadensis EESA01
• The number of years it takes, given a specific rate of increase, for a number
(such as population) to double.
1979 China growth rate = 2.8% (popl’n at time: 1B)
Current global growth rate = 1.2% (now: ~6.9B)
Current Canada growth rate (natural and net immigration together) = 0.9% (now:
Global Population Growth IT TOOK MOST OF HUMAN HISTORY (UNTIL ABOUT 1800) FOR THE
GLOBAL POPULATION TO REACH 1 BILLION.
2 BILLION BY 1927.
3 BILLION BY 1960.
WE HAVE DOUBLE OUR POPULATION SINCE 1966.
7 BILLION PEOPLE ANTICIPATED POPULATION BY 2011.
DECLINED TO ~1.2%, WE ARE STILL GROWING AND EVEN A SMALL
RATE WITH SUCH A LARGE POPULATION NUMBER IS SEVERELY
COMPOUNDED OVER TIME (MUCH LIKE A NICE BANK ACCOUNT).
• “The maximum population size of a
species that a given environment
• Limiting factors
• Births ≈ deaths
Earth’s carrying capacity? Between 10
million and 33 billion.
Carrying Capacity Uncertainty EESA01
4 Distinct Increases in Carrying Capacity for Humans
A. Progressive diffusion
from original centres
B. Surges in population:
Cultural Revolution during Paleolithic Period
Cultural Revolution/Paleolithic Period:
• Development of tools; stone, bone, wood
(Note animal tool use – crows)
• Omnivorous diet
• Manipulation of fire
• Development of speech and communication
Ethiopia: 2.6 My bp
Tanzania: 1.75 My bp
• Little evidence of population at time.
• Start ~ 10-12,000 years bp
• Transition from nomadic hunter-gatherer to settled farmer (environmental
manipulation to meet needs)
Reduction of area needed per person
500 X population density
Excess of food production over minimum
Whole population need not be in food production or acquisition
Establishment of settlements
Social structures – priests – accountants – salesmen
“Fertile Crescent” – note soil salinization & collapse of society