World Population: Growth & Trends

Demographic Questions Why is population growth so central to environmental problems? What is the current population? What will it be in 2050? What factors affect population growth rates? How do growth rate compare in developed vs. developing countries? What is a "demographic transition? What are its stages? Interpreting Population Pyramids. Understanding modern demographic trends.

Developed Country Developing Country Low birth rate Most of the people are over 15 years of age Long life expectancy Low infant mortality rate Most people live in urban areas (cities) High per capita Gross Domestic Product High literacy rate Highly industrialized People make a living in secondary or tertiary economic activities High birth rate Most of the people are less than 15 years of age Low life expectancy High infant mortality rate Most people live in rural areas (country side) Low per capita Gross Domestic Product Low literacy rate Little industry People make a living in primary economic activities.

World Population: 7.6 billion As of Dec, 2017 (Super)exponential growth

Exponential Growth J curve Population growth after 1800’s ranged 1.2-1.9%! Super-exponential growth Post-1960 was first time EVER that population doubled within a generation

Population by 2050: 9 billion

Factors affecting Growth Rate Growth rate = Birth Rate - Death Rate 1.3% = 2.2% - 0.9% (early 2000s) 1.1% = 1.9% - 0.8% (today) Of these the Birth Rate is the most important contributor, specifically the Fertility Rate (#children/woman) 2.42 children/women (World) 1.6 children/woman (Canada) Why? Because death rates have stabilized...

Factors affecting Birth Rate Global BR = 1.9% or 19/1000 Lessons on population control from Thailand, South Korea, Japan, India, and China: Invest in Family Planning Reduce poverty Elevate the status of women

Factors affecting Death Rate Global DR = 0.8% (higher in LDC vs MDC) Low death rates due to: medical treatments, better food supplies and nutrition, improvements in sanitation, and access to clean water Lower DR is the main reason for the global population increase

INFANT MORTALITY When infant mortality rates rise…. Population actually increases Why?

ANSWER For many parents in the developing world their only sense of old age security is their offspring. If the death rates are high when their babies are born, they must have more children to ensure the survival of a son to care for them

Population Projections Current ~7.6 billion (and rising), growth rate: 1.1% (and falling…). Projected 2050 population: Approximately 9 billion

Calculating Doubling Times The “Rule of 70”: Doubling time = 70/percentage growth rate Example: Current growth rate is 1.1%, so doubling time is 70/1.1 = 64 years (ca. 2080). Projected pop near 2080 would be ~14 to 15 billion if the growth rate stays the same. But this won’t be the case… why?

Carrying Capacity At the heart of this issue is the concept of Carrying Capacity (K) the maximum number of individuals that the environmental resources of a given region can support. Population growth and Carrying Capacity co-evolve. Factors: Technology, social, political, economic institutions, physical & ecological environment.

Where people live

Population growth rates