sgcep scie 1121 environmental science spring 2012 section...

SGCEP SCIE 1121 Environmental Science

Spring 2012Section 20531

Steve Thompson: [email protected]://www.bioinfo4u.net/

1Sunday, February 12, 2012

mailto:[email protected]?subject=

mailto:[email protected]?subject=

http://www.bioinfo4u.net/

http://www.bioinfo4u.net/

First, you all did quite poorly on the exam; let’s go over those questions that you most messed up.

2. Which of the following statements is true regarding human population growth?

A. The earth will always be able to support human populations, regardless of how much this population growsB. People in third world,’ developing countries have the same average income as in developed countriesC. The smallest population increases will be in ‘third world,’ developing countriesD. Human population growth is projected to stabilize in the next 100 years

10. The difference between a hypothesis and a theory is:A. Theories (not hypotheses) are educated guesses about the causes and effects of observed phenomenonB. Hypotheses (not theories) are logically consistent across all observations and often include many theoriesC. Hypotheses (not theories) can predict the outcome of future observationsD. Theories (not hypotheses) are a valid interpretation of reality 2

Sunday, February 12, 2012

13. As a nation’s income level rises:A. Some problems, such as inadequate sanitation, increase through taxes and technologyB. Some problems, such as urban sprawl and CO2 emissions, continually decreaseC. Some problems, such as little access to safe water, decrease over timeD. Some problems, such as air pollution, are not affected at all

18. Which of the following statements is not true according to the article from The Nation that I asked you all to read?

A. Mexican pig farmers were no longer able to work locally due to NAFTA and illegally migrated to USA pig farmsB. The North American Free Trade Agreement (NAFTA) eliminated barriers to trade within North AmericaC. The passage of NAFTA dramatically increased the wealth of Mexican pig farmersD. Pig farming has serious environmental problems regardless of where it is done 3


23. An interactive complex of all the organisms and the non-living components of any particular time and place is called:

A. A biomeB. An ecotoneC. A biosphereD. An ecosystem

33. Which of the following statements does not pertain to organisms known by the ecological term consumers?

A. They often use the process of cellular respiration to break down complex organic molecules to produce energyB. They have the capability to make their own high-energy organic molecules from inorganic raw materialsC. They are organisms that support their lives by feeding on the other life formsD. Cellular respiration uses glucose to produce carbon dioxide 4


35. Nitrogen fixation is the process whereby inorganic N2 is ‘fixed’ into organic form; which of the following is true?

A. This is largely accomplished by symbiotic bacteria in the root nodules of legume plantsB. Since there is plenty of nitrogen in the air, it is seldom a limiting nutrientC. All organisms can directly use the nitrogen gas within the atmosphereD. It has little consequence to the rest of life on Earth

38. Population density-dependent factors that affect the carrying capacity of a species in an ecosystem (i.e. density-dependent environmental resistance factors) do not include which of the following?

A. Availability of appropriate habitatB. Availability of appropriate foodC. Level of predationD. Wildfire


So now an in-class assignment, this time regarding . . .Why you did so terrible on this first test!Remember . . . each sectional exam is only worth 10%, so it’s not that big of a deal, yet. Think of it as a “wakeup call.”And, maybe now you’ll realize that you actually will need to work for this class. And, perhaps you’ll realize just how much the extra-credit homework component of the class can help . . . as much as an entire sectional exam!Seriously, it was a very fair exam . . . only those concepts that I most emphasized in class were on it. Therefore, . . .On a piece of paper — name, date, class and section (Sci 1121-20531), and . . .How can you do better next time? Did you study at all; how much? Are you printing out my lectures and annotating them as I talk? Are you then taking those points that I emphasized and making your own study guide, whether that’s an outline or index cards . . . .Quietly work on this by yourself for the rest of the class period — come up with no more than one page — and get it to me as you leave.


Now, the human population• Life circumstances give people different health

concerns, access to education, medical care, etc.•And, different family sizes and resource use.

• In the 20th century, human population tripled.• But, the rate of growth is slowing ; However . . .•Not the increase in absolute numbers.

• Technology has led to improved well-being, . . .• But extreme poverty is still widespread.

• Humans are exceptional animals, because . . .• They can think and make decisions about their

lives, just not always the correct ones.7


Human population ecology• Humans are part of the natural world, so . . .• They are subject to the same processes (e.g.,

births, deaths) as all organisms.• Human population growth has shown a J-

shaped (exponential) curve for much of history.• However, by 2100 it may show an S-shaped,

logistic curve.• Demography: collecting, compiling, and

presenting information about human populations. Includes . . .•Migration, fertility changes, mortality;• Economic, cultural, social, and biological

factors;•And wealth and health care.


World population growth

9

As of right now6.994 billion

according to theUS Census Bureau,7 billion according

to the UN!


Remember r- & K-selection• r-selected species have high reproductive

potential, mainly limited by their population growth rate (r). Versus . . .• K-selected species, which remain close to their

carrying capacity (K), with . . .• Longer life spans, older age at first

reproduction, parental care, fewer offspring.• So we are pretty much K, but . . .• Humans are critically different from other

species in that humans . . .•Mostly K-selected stuff going on,• But show exponential growth (r-strategists).

• This is because of technological “revolutions.”10


The Neolithic revolution• Humans rose in Africa 200,000 years ago.• Paleolithic (50,000-10,000 years ago) humans

lived in small tribes as hunter-gatherers.• The tribes moved constantly as food ran out.• Predators, disease, famine were common.

• Neolithic revolution (rise of agriculture): produced abundant food 12,000 years ago.• Reliable food from animal husbandry and

agriculture.• This resulted in settlements and the

specialization of labor.• Technology produced tools, trade, cities, and

food storage.• Reduced mortality + food = population growth!


The industrial revolution• For 11,000 years, the population grew and spread.• Cultures increased their knowledge and mastery

of the world.• Birth of modern science and technology in 17th

and 18th centuries fueled population growth.• Then the Industrial Revolution: technology

energized by fossil fuels.• Coal, oil, and natural gas let people do much

more work than by human or animal power.• This extra energy lets people produce more food.• But also produced pollution and resource

exploitation.12


The medical revolution• Before the early 1800s, human populations grew slowly and

fluctuated; especially due to . . .• Diseases (e.g. smallpox, diphtheria, measles, scarlet fever)

that hit infants and children hardest, and . . .• Epidemics (e.g., the black plague) that killed adults.

• High reproductive rates were balanced with natural enemies (e.g., diseases), resulting in a low population growth rate.

• Then many diseases were vanquished as scientists showed they were caused by infectious agents and transmitted via water, food, insects, rodents. There were . . .

• Spectacular decreases in child and infant mortality due to:• Vaccinations• Cities and towns treating sewage and drinking water• Penicillin (and other antibiotics)• Nutritional improvements

• High birth rates and low mortality rates resulted in exponential population growth


The green revolution• Concerns over producing food for larger and larger

populations led to increased agricultural efficiency.• This was done with pesticides, irrigation, and

fertilizers — all increased yields.• Countries could feed their growing populations.

• However, industrialized agriculture came at significant costs:• Erosion, soil and water pollution, loss of native

plants — all associated problems; plus . . . • Resources (soil, water) were used faster than

they were replaced. Furthermore . . .• Resistance develops in target organisms such

that they are no longer affected by the pesticides. 14


The newest revolution• Technological breakthroughs . . .• Have produced the Internet, computers,

nanotechnology, robotics, genetic engineering, and solar and other ‘green’ sources of energy.

• A new environmental revolution will come from:• Efficient technologies, urban and regional

planning ;• Policy and industrial changes; and . . .• Personal decisions.

• Humans are a part of the natural world although they can produce drastic changes. Yet . . .•Natural laws still apply to people.


Do humans have a carrying capacity?• It is hard to determine a carrying capacity for humans.• Some claim our ingenuity is the ultimate resource, such that . . .• There is no human carrying capacity. Plus, in the past . . .• People have overcome carrying capacity limits through these

‘revolutions’ of thought and action. And with the . . .• Law of limiting factors, when a limit is removed, populations

grow.• However, population increases have come with large costs:• Pollution is rampant; pandemics quickly spread;• Nonrenewable resources are being depleted;• Agricultural land, aquifers, fisheries, etc., all being lost!

• Humans increase their short term carrying capacity, but the . . .• Trade-offs are paid in the long term. Furthermore, . . .• The number of people the Earth can support depends on the

living standard people are willing to accept . . . eating meat, traveling, heating and cooling homes, using paper, on ad infinitum.


Population size predictions• Best estimates for human carrying capacity: ~ 7.7 billion.• Estimates of actual numbers? Far more than this!• Think about it: By 1830, there were 1 billion people.• It took about 100 years to reach 2 billion.• Yet it’s only taken 13 years (1999-2012) to go from 6

to 7 billion!• The United Nations predicts . . .• By 2050, there will be 9.1 billion people.

17

Animation: Human Population Growth

http://www.youtube.com/watch?v=sc4HxPxNrZ0http://ngm.nationalgeographic.com/7-billion


http://www.bio.fsu.edu/~stevet/SGCEP/Sci1121/population.swf

http://www.bio.fsu.edu/~stevet/SGCEP/Sci1121/population.swf

http://www.youtube.com/watch?v=sc4HxPxNrZ0

http://www.youtube.com/watch?v=sc4HxPxNrZ0

http://ngm.nationalgeographic.com/7-billion

http://ngm.nationalgeographic.com/7-billion

18

Here’s a graph

of that growth.

See http://www.youtube.com

/watch?v=4BbkQiQyaYc


http://www.youtube.com/watch?v=4BbkQiQyaYc








And of the rise and fall of the rate of growth, since

1950 worldwide.

19http://en.wikipedia.org/wiki/File:World_population_increase_history.svg

What happened

here?


http://en.wikipedia.org/wiki/File:World_population_increase_history.svg

http://en.wikipedia.org/wiki/File:World_population_increase_history.svg

However, different nation’s . . .• Peoples live in radically different economic and demographic

conditions. Furthermore, even . . . within a single country there can be tremendous disparities.

• Regardless, countries can be categorized by average per capita gross national income:

• High-income, highly developed, industrialized countries:• ~ $38K/yr — U.S., Canada, western Europe, Taiwan, Israel.

• Middle-income, moderately developed countries: • ~ $6.2K/yr — parts of Africa, China, some Arab states

• Low-income, developing countries:• < $936/yr — parts of Africa, southern Asia, some former Soviet

republics• The disparity of wealth between countries is mind-boggling ; e.g. . . .• High-income countries = 15% of the population, 80% of the

wealth; versus . . .• Low-income countries = 37% of the population, but only

3% of the wealth.• The poorest of the poor are extremely bad off.


Economic divisions of the world


22

Another way to picture poverty


Countries with affluence• Wealth allows conservation, management, better

agriculture, and pollution control. However, . . .• Developed countries produce the most pollution:• Climate change, ozone depletion, wastes, toxic

chemicals, etc.• The world’s richest 20% is responsible for 86% of

all consumption and 80% of trade. Causing . . .• Depleted fisheries, deforestation, oil spills,

problems associated with mining, etc.• The wealthy transfer their waste to distant

locations —• They do not see or feel the impacts of getting

those resources.23


The impact of wealth• Poorer countries resent being told to protect their

resources, while they see . . .• Wealthier nations using environmentally unsound

processes. Yet these wealthy nations . . .• Aid poorer countries to help pull them out of poverty,

slow population growth, and promote sustainability.• Wealth can help solve environmental problems:• To lower pollution, clean water, treat sewage, etc.

• But the relationship between economic wealth and environmental health is not so clear-cut• Some issues (e.g. disease) may improve, but others

(e.g. waste) increase. Moreover, . . .• Environmental impacts are not always experienced

at the same place where resources are being used.24


Enter stewardship• Developed countries have their own problems with

consumption, affluence, damaging technologies, and wastes that must be addressed to achieve sustainability. This . . .• Requires wise leaders and effective policies;

and . . .• Needs willpower and the ethics to care for others.

• The US, a very rich country, also has large differences between groups in health care and access to services:• It ranks lowest in life expectancy, and . . .• Has more people in prison and children in poverty

than any other high-income country!• Changes can only come about through responsible

and ethical action in the voting booth.25


India

China

all of Africa

Other less developed regions

More developed regions

And growth is very

different in different countries based on economic

development.


Population growth differs dramatically!• Population growth rate in high-income countries

= 0.1%/yr. This . . .•Adds less than one million humans/yr.

• Growth in middle- and low-income nations = 1.5%/yr. In contrast, this . . .•Adds 75 million/yr (98% of population growth).

• Population growth occurs when births > deaths.• Total fertility rate (TFR): average number of kids

each woman has over her lifetime. Therefore, . . .• If TFR = 2.0: the population is stable;• If TFR > 2.0: the population grows; and . . .• If TFR < 2.0: the population shrinks.


Fertility rates differ accordingly.

• Total fertility rates have dropped worldwide, especially in developed countries (TFR = 1.1-1.6).• The US is a bit higher: TFR = 2.1. However, . . .

• In developing countries: TFR = 2.8–6.8+ So, . . .• By 2075, 90% of all people will live in developing nations.


And they differ over time: e.g. total fertility rate, United States, 1920-2008.


Reduced total fertility rates have a large effect.In the 1960s, the global TFR was 5.0 children per woman. It is now 2.6.

The age at which a woman first reproduces also affects population growth. Therefore, . . .Earlier reproduction results in higher growth.The UN Population Division predicts that the population will reach 9.2 to 11.9 (if current fertility rates remain unchanged) billion by 2050, and then level off later sometime in the 22nd century.

30

Globalpredictions

For a population smaller than today, fertility rates must be even lower than

the UN’s low fertility scenario.


During the 1960s world population growth rate peaked at 2.1% per year, then began a steady decline.Twenty years (~1 generation) later, the number of people added each year peaked at 87 million.The number added each year declined when the growth rate fell low enough to offset the increase in the number of reproducing people from 20 years before.Reduced growth rates and number of people added came from reduced total fertility rates.

31

Population growth rate and absolute growth


Population profiles• . . . are bar graphs

showing the number of people (males and females) at each age for a population.• Data are collected

through a census.• Age structure: the

number of people in each age group at a given date.• Each bar

represents one cohort (group of the same age).

• Here, the USA in ’85, ’05, and ’50. 32


Projecting populations: a developed country

33

Developed countries with low fertility rates show a

dramatic increase in the number of old

people.A graying

population with a high

proportion of elderly causes

its own problems, e.g.overwhelming

pension systems, over-stressing

medical facilities, etc.

Notice the shift of the bulge!


Projecting future populations: a developing country

34

• Declining fertility rates in developing countries are still well above replacement level fertility.• They have an

average TFR = 3.2.• Their population

profiles are pyramid shaped.

• High fertility rates maintain a young population.• 40-50% of the

population is younger than 15.


Planners use population profiles.• In high-income countries, the proportion of

people dying before age 60 is small.•The population profile below 60 echoes past events that affected birthrates.

• The “baby boom” resulted from returning World War II veterans starting families.•The “baby bust” resulted from declining fertility rates.•Recently, there has been a “baby boom echo.”

• Planners use population profiles to understand the probable needs of society in the future. 35


Population projections for the United States

36

• Total fertility rates and immigration profoundly affect population estimates.

• US fertility rates increased to 2.1 in the 1980s.• Along with immigrants,

the projected population size won’t be 300 million, but 420 million by 2050.• The population will

continue growing after 2050.

• Concerns about sustainability have brought U.S. population policy under heavy debate.


Population momentum is . . .• The effect of current age structures on future

populations.• A young population has positive momentum

because . . .•Many children are entering their reproductive

years;• Even if each woman has two children, births will

still exceed deaths.• A stable population will be obtained only when the

population has been at replacement level fertility for decades. Population growth can not be stopped quickly.• But the earlier fertility rates are reduced, the sooner

population growth can be ended.37


The demographic transition . . .• Is a shift in birth and death rates from the primitive to the

modern condition in industrialized societies.• Modernization results in lower death rates, better health

care, declining fertility rates.• In the first stage birth and infant and childhood mortality

as well as adult death rates are high (low population growth), so undeveloped societies have stable populations.• In the second stage the death rates lower due to improved

living conditions, but birth rates remain high (rapid population growth).• In the third stage birth rates fall and death rates remain

low, such that developed societies have stable or even declining population growth due to more deaths than births.• The key question is: what must happen to help developing

countries reach this third stage?38


The demographic transition graphically:

39

Also see http://www.globalchange.umich.edu/

globalchange2/current/lectures/human_pop/human_pop.html

undeveloped developedSunday, February 12, 2012

http://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html








And another way to see

the demographic transition: contrast

developed and developing countries.


Or break the demographic transition into stages.


Regardless, it’s time to end.Next time we’ll look at the factors that influence human population growth rates and the demographic transition in a bit more detail . . .

Economic development,Resource management,Improved education and health,And access to family planning.


sgcep scie 1121 environmental science spring 2012 section...

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