Global Environmental Problems

Spring 2006

Problem Set #3

Due: 22 February

1.

In chapter II of Harte, read problem 1 ("School as a Steady-State System") and do exercises 1 and 2.

2.

In chapter II of Harte, read problem 2 ("The Water Above") and do exercise 1.

3.

In chapter II of Harte, read problem 6 ("A Polluted Lake"). Now consider a lake with a volume of 10,000 acre-feet and a stream outflow of 1,000 acre-feet per year. If the mercury concentration in the lake is a fairly constant 1 ppm, and the only exit path for mercury is stream outflow, at what rate does mercury flow into the lake?

4.

The average American generates about 5 pounds of waste per day. About 40% (by weight) is paper and paperboard. Roughly 40% of all paper and paperboard waste is recycled and 20% is burned (with or without energy recovery); the remainder is buried in landfills, where it decomposes. The residence of paper in a landfill is about 10 years. If waste generation and disposal practices remain roughly constant for several decades, roughly how much paper per capita is in landfills?

5.

Referring to problem 5 in problem set #1: 

A.

About half of the motor oil that is released into the environment, either through leaks, exhaust fumes, or illegal disposal, runs off into rivers and streams and, ultimately, the Chesapeake Bay. What is the annual flow of oil into the Chesapeake Bay?

B.

What is the total amount of oil in the Bay?

C.

What is the average concentration of oil in the Bay?

6.

Referring to problem 1 in problem set #1, what were the average growth rates of oil, gas, and coal consumption during the most recent 10-year period? What are the corresponding doubling times? You may use data from just one of the three sources.

In 2000, per-capita GDP in the United States was about $34,000/y. Over the last 50 years (indeed, over the last 100 years), real (i.e., inflated-adjusted) per-capita GDP has increased at an average rate of 2 percent per year (r = 0.02/y).

A.

At this rate, how many years does it take per-capita income to double?

B.

Based only on your answer to A, estimate per-capita GDP in 2100 if per-capita GDP continues to grow at 2 percent per year. (HINT: how many times will it double?)

C.

Calculate the answer to part B more precisely (using F₀e^rt).

8.

In 2000, per-capita GDP in China was about $4,000/y (adjusted for purchasing power). Over the last 20 years, real per-capita GDP has increased at an average rate of 8 percent per year.

A.

If r = 0.08/y, what is i?

B.

If growth continues at this rate, in what year would per-capita GDP in China equal current per-capita GDP in the United States?

C.

If per-capita GDP continues to grow at 8 percent per year in China and 2 percent per year in the United States, in what year would China catch up to the United States? What would the per-capita income be in both countries at that time?