CHM 110 - CHEMISTRY AND ISSUES IN THE ENVIRONMENT
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| Instructions to submit the files for grading. | |||
Dr. Charles E. Ophardt, Elmhurst College, Elmhurst, Illinois. Copyright 1997
HUMAN SOCIETY AND ENVIRONMENTAL IMPACTS
GLOBAL COLLAPSE
OR
SUSTAINABLE FUTURE ?
INTRODUCTION: This exercise is based upon the results of a global computer model constructed to model the interaction of five variables - population, food supply, industrial output, pollution, and consumption of nonrenewable natural resources. The results of the computer model scenarios are presented as a series of graphs plotted over a 2 century time frame. The computer program "Limits to Growth" presents the graphs in a variety of ways to enable the use of the scientific method to compare and analyze the results of a variety of changes presented in scenarios. The actual "Limits to Growth" program is not available over the inernet, but the results of the computer model are available as graphs in this exercise.
The Overall Question to be answered at the end of this exercise is:
Which worldview is supported by by the
assumptions in this computer model of the world?
TABLE OF CONTENTS
World Views
Exponential
Growth
B. Growth of Savings: C. Doubling Time:
It is useful to think of exponential growth in terms of doubling time, or
the time it takes a growing quantity to double in size. For example, money
in a savings account at 7% interest will double in 10 years.
| Growth Rate | Doubling Time |
| 0.1 % per year | 700 years |
| 1.0 | 70 |
| 2.0 | 35 |
| 4.0 | 18 |
| 5.0 | 14 |
| 1700: The world population was about 0.5 billion and was growing at a rate of approximately 0.3 % per year (corresponds to a doubling time of 250 yr). |
| 1970: The population totaled 3.6 billion and a rate of growth of 2.1 % per year (doubling time is 33 years). |
| 1991: The population was 5.3 billion, rate of growth is 1.7 % (doubling time is 40 years), despite recent drops in birth rates in some countries. |
What is the cause of exponential population growth?
| Pre-industrial (1700): Both fertility and mortality were comparatively high and irregular. The birth rate exceeded the death rate only sightly, population grew exponentially, but at a very slow rate. The average life expectancy was 30 years. | Modern (1970): Modern medicine, public health, and adequate food have led to an average life expectancy of 53 and still rising. Birth rates far exceed mortality rates, which results in a sharp exponential growth of the population. |
| Pre-industrialized: Such as many in Africa, have high mortality and even higher fertility - growth rate = 2-3%/yr. | Intermediate Industrialization: Such as Egypt, Mexico, Thailand, have low mortality while fertility is still high but also decreasing - growth rate = 2-4%/yr. | Highly Industrialized: North America, Europe, Japan, have low mortality, low fertility, and slow growth rates - less than 1% per year. |
| The left hand axis has different values for the units being plotted. The actual numbers are not important, but will be relative for all of the scenarios. The five properties are all scaled to fit on one graph. |
1 = Green = Population: increases to 6 billion by 2000. The simulated
world tries to bring all people into the industrial and post-industrial
economy. Reaches a maximum about 2030 and begins to decline - probably because
the food supply started to decrease 10-20 years earlier.
2 = Blue = Food Supply: The agricultural sector grows and begins
to increase food per person, but begins to decrease sharply at 2015.
3 = Black = Industrial output: Grows until a combination of environmental
(pollution = 4= red) and natural resource (5 = purple) constraints eliminate
the capacity of the capital sector to sustain investment.
4 = Red = Pollution: Steadily increases as industrial output increases
(3 = black) and...
5 = Purple = Nonrenewable resources: begins to decline more sharply
after 2000. Eventually the lack of resources causes the industrial output
(3 = black) to decrease.
In this Scenario 1, no extraordinary efforts are made to abate pollution
or conserve resources. Both begin to increase rapidly.
...THE LIMITS TO GROWTH ARE REACHED... The objective of this exercise is to find a scenario where the graph lines become and remain horizontal. |
Industrial capital begins to depreciate faster than new investment can
rebuild it.
As it falls, food and health services also fall, decreasing life expectancy
and raising the death rate.
In this scenario, shortly after 2010 the growth of the economy stops
and reverses because of a combination of LIMITS.
1. Pollution rises high enough to effect land fertility.
2. Land erosion increases.
3. Economy shifts to more investment in agriculture.
4. Resource sector also beginning to sense limits and requires more investment.
5. Capital is diverted to producing more food and resources.
6. Less capital for other growth, cannot keep up with depreciation.
7. Capital plant begins to decline taking with it the food and service sectors.
8. For a short time population continues to rise.
9. Finally, increasing death rate, caused by lack of food and health services,
causes population decline.
End Introduction and Start of Simulated Laboratory:
| This is finally, the start of the laboratory exercise. It would be most helpful for you to download the brief text file version of the questions and print a hard copy. You can write in the answers as you go along with the computer. | Brief Text report version |
| Then later open the text file in a word processor to type in the answers, and then finally email the anwers to the instructor. | Instructions to submit the files for grading. |
| This exercise is not designed to be very hard. We are just looking for general trends in the graphs and changes in the graphs from one scenario to the next. To complete this exercise you will be applying elements of the scientific method. One scenario will serve as a "control", while the second scenario will have a change of one or more variables. By comparing the two or more scenarios, you will be able to draw conclusions about the cause and effect relationships of the variable changes. | |
| NOTE: The first several questions are mostly answered for you, just fill in the blanks. We are looking for things like increase, decrease, rise rapidly, stay constant, give an approximate year, etc. Eventually you will need to make your own intrepreations of the graphs in future questions. | |
Scenario 2: Doubled Resources
- The number of estimated natural resources is doubled from the
current "best" estimate.
Since the amount of nonrenewable resources still to be discovered are simply
unknown, the model can be used to test this range of uncertainty. In this
scenario it is assumed that there are twice as many resources waiting to
be discovered than were assumed in Scenario 1.
QUES. 1: What if more resources are actually available
than current estimates predict? (Fill in the blanks below for answer)
a. When comparing Scenarios 1 and 2, the resources (purple) last considerably longer, but the general behavior of the model is still overshoot and collapse, just delayed by 30-40 years. Additional resources allow industry (black) to grow _____ years longer in Scn 2 than Scn 1, which in turn causes pollution (red) to be ____ times higher and peak ____ years later. b. In Scn 2, population (green) rises to more than 9 billion in 2040, which in turn increases the pollution to _______ levels than in Scn 1. The greater pollution has a greater impact on the food supply (blue), causing it and population (green) to _____ more sharply than in Scn 1. The higher pollution reduces land yield and forces much greater investment in agriculture. Eventually declining food raises the death rate to decrease the population. |
Scenario 3: Doubled Resources and
Pollution Control Technology
Allocate capital to bring pollution to 1975 levels. 20 year lag time.
In scenario 2, growth was ended by a pollution crisis. What if the simulated
world responded by making a determined investment in pollution control technology?
In scenario 3, and all further runs, we assume double resources
and apply one variable change at a time.
In scenario 3, we have assumed that in 1995, long before pollution rises
high enough to cause measurable damage, the world decides to bring pollution
down to 1975 levels and systematically allocates capital to achieve that
goal.
Pollution control technology is applied at the "end of the pipe"
approach to control emissions, rather than reducing throughput at the source.
It reduces pollution emitted by up to 3% per year until brought down to
1975 level. It is also assumed that it takes 20 years for any new pollution
abatement technology to be developed and installed worldwide.
QUES. 2: What is the effect of applying all pollution
control technologies? Fill in the blanks below.
a. In this scenario, pollution continues to rise in spite of the abatement programs, because of the delays in implementation and continued growth in agricultural and industrial production. Scenario 3 has pollution control technology, pollution (red) stays ______ than in Scenario 2, but it does reduce land fertility after about 2015. b. In Scn 3, population (green) continues to grow to about the same level at 2050, but does not ____ as drastically. In Scn 3, food (blue) stays at ______ levels as in scenario 2. c. In Scn 3, total industrial output (black) peaks by 2035 at a _____ level than in scenario 2, because so much capital has been pulled into agricultural, resource, and pollution sectors. |
Scenario 6: Double Resources, Pollution
Control Technologies, Land Yield and Erosion Control Technologies, and Resource
Efficiency Technology.
In this scenario, double resources are assumed, as well
as a variety of advanced technologies including pollution control already
described.
Land yield technologies are applied in 1995, well in advance of a global
food crisis, new technologies such as genetics, more fertilizer, and pesticides
are applied. Capital inputs are needed to achieve a 2%/year increase in
land yields. This implies a 7 times increase in 100 years!! The model tries
to reduce land erosion by a factor of 3.
A final program of resource efficiency technology is instituted to reduce
the amount of nonrenewable resources needed per unit of industrial output
by 3 % per year until total resource consumption decreases to the approximate
1975 level.
QUES. 3: What is the effect of applying all advanced technologies possible? Fill in blanks below for the answer.
a. In Scn 6, this combination of technologies permits the simulated world economy to go on growing smoothly until ______ years. b. In Scn 6, nonrenewable resources (purple) are depleted more ________ than in Scn 2; their cost remains low. Industrial output (black) peaks at _____ year and then begins to ______ more slowly. c. Food production (blue)_____ steadily, but pollution gets high enough to depress land fertility, but its effect can be overcome by additional agricultural inputs. d. Population (green) appears to become almost ______ by the year 2100. Eventually death rates rise to equal birth rates. Although right at the edge of the graph at 2100, more gradually but still inevitably, the world over shoots its limits. It cannot maintain living standards, population and food will begin to fall following the decrease in industrial output. |
QUES. 4: What happens if the population is controlled and no other things are changed? (Fill in the blank below)
As a result the world population continues to grow moderately to 7.4 billion in 2040. a. In Scn 8, surprisingly, industrial output (black), pollution (red), and food supply (blue) all peak at the ________ time and collapses (graph lines go down) at roughly the_____ time as in Scenario 2 for the same reasons. The larger industrial plant emits more pollution and use more resources. b. Given the present limits and technologies as seen in Scn 8, the world _______ sustain 7.4 billion people with an ever increasingly per person industrial output. |
QUES. 5: What happens if all advanced technologies are applied, as well as, population control, and moderate standard of living? (Fill in the blanks below.)
a. The result of scenario 10 is what might happen in a sustainable world society. Population (green), food (blue), industrial output (black) graph lines are _______________ after about 2030. For the first time we see that a more restrained society is at a rough state of equilibrium. Capital does not have to go either toward further growth or to offset a spiraling set of problems. A population of just under 8 billion lives at a reasonable standard of living. b. In Scn 10, nonrenewable resources deplete _________ so that more than half are still present at 2100 conmpared to Scn 2. This is a picture of a SUSTAINABLE SOCIETY. The graph lines show _______ trends. Society is expending considerable effort to protect the land, reduce pollution, and use nonrenewable resources highly efficiently. |
QUES. 6: What if technologies are brought on faster with
delay reduced from 20 years to five years?
Discuss the results following the model answers from previous questions. What if technologies are brought on faster with delay reduced from 20 years to five years? |
Scenario 11: Stabilize Population;
All Technologies from Scenario 6 and Moderate Industry and Lower Standard
of Living; apply controls in 1975 with 20 year lag time.
What is the difference in applying sustainability policies 20 years
sooner?
Scenario 11 is exactly the the same as in Scenario 10, except that the policy
changes were all applied in 1975 rather than 1995. This is 20 years backwards
in time, a future that might have been, but is no longer available.
Scenario 12 Stabilize Population;
All Technologies from Scenario 6 and Moderate Industry and Lower Standard
of Living; apply controls in 2015 with 20 year lag time.
What happens if further delays occur before sustainable policies
are adopted and put into effect? Twenty years forward to 2015 will make
a big difference if you remember the mathematics of exponential growth.
By that time it may be too late to avoid some very serious problems.
Compare: Scenario 11 - all controls in 1975
Scenario 10 - all controls in 1995
Scenario 12 - all controls in 2015
QUES. 7: a. Discuss and compare the results of these three scenarios. b. What is the effect of the starting time on the implementation of all policies with a 20 year lag time? c. What happens if we wait too long to apply controls?
|
QUES. 8: a. What happens if the standard of living
is too high and requires excessive industrial output?
Discuss the results. |
QUES. 9: Which worldview is supported by by the assumptions in this computer model of the world? Explain. |
| QUES. 10: Which worldview most closely corresponds
to your own view point? Explain how you view some of the issues such as
the use of resources, population control, and the use of the nature. |
References:
1. Meadows, D.H. & Meadows, D.L., et al, "The Limits to Growth",
New American Library, 1972.
2. Meadows, D.H. & Meadows, D.L., Randers, J., "Beyond the Limits",
Chelsea Green Publishing Co., 1992.
3. Graphs from STELLA II software, World3 Model.
