To understand them, consider our concern with world population. Today, there are more than 6.5 billion people, and that number may grow to around 9 billion within this half-century. Several decades ago, many people considered rising population to be the main challenge facing humanity. Now we realize that it matters only insofar as people consume and produce.

If most of the world's 6.5 billion people were in cold storage and not metabolizing or consuming, they would create no resource problem. What really matters is total world consumption, the sum of all local consumptions, which is the product of local population times the local per capita consumption rate.

The estimated one billion people who live in developed countries have a relative per capita consumption rate of 32. Most of the world's other 5.5 billion people constitute the developing world, with relative per capita consumption rates below 32, mostly down toward 1.

The population especially of the developing world is growing, and some people remain fixated on this. They note that populations of countries like Kenya are growing rapidly, and they say that's a big problem. Yes, it is a problem for Kenya's more than 30 million people, but it's not not a burden on the whole world, because Kenyans consume so little. (Their relative per capita rate is 1.) A real problem for the world is that each of us 300 million Americans consumes as much as 32 Kenyans. With 10 times the population, the United States consumes 320 times more resources than Kenya does.

People in the third world are aware of this difference in per capita consumption, although most of them couldn't specify that it's by a factor of 32. When they believe their chances of catching up to be hopeless, they sometimes get frustrated and angry... People who consume little want to enjoy the [benefits of] the high-consumption lifestyle [though may not be aware of its costs in terms of stress, less free time, etc, plus environmental costs]

Among the developing countries that are seeking to increase per capita consumption rates at home, China stands out. It has the world's fastest growing economy, and there are 1.3 billion Chinese, four times the United States population. The world is already running out of resources, and it will do so even sooner if China achieves American-level consumption rates...

Per capita consumption rates in China are still about 11 times below ours, but let's suppose they rise to our level. Let's also make things easy by imagining that nothing else happens to increase world consumption -- that is, no other country increases its consumption, all national populations (including China's) remain unchanged and immigration ceases. China's catching up alone would double world consumption rates. Oil consumption would increase by 106 percent, for instance, and world metal consumption by 94 percent.

EXERCISE 1: Confirm the above claim that if China "catches up" oil consumption would roughly double ("increase by 106%") as the article asserts. Hints: 1) you may wish to look up the population of China (and of the US if necessary) on wikipedia.org 2) You will want an estimate of "what percentage of the world's resource does the US consume" -- assume the answer is 25% (This is true in the case of oil)

METHOD #1 for solution:
China population: 1,329,349,388 (2007 ; or just use "1.3 billion" in article
and you'll get very similar final numbers)

US population: 300 million.

Let's use X to stand for the consumption level per person in China.

Then 11·X is the consumption level per person in the US.

Thus in the US, 300 million consume how many "units" of consumption?

11X times 300 million = "3300·X million units"

Rough figure: the US currently consumes 1/4 of world's resource (true 
for oil; roughly correct for many other resources)

So total World consumption would be "13200·X million units"

Now, How much does China consume? 

Total Consumption = (Per-Person consumption) · (Population)

Thus:
Total China Consumption = (China's per-person consumption)·(China Population)

= X · (1330 million people) = 1330·X million units; if china consumed
like the U.S. it would consume 11·(1330·X million) thus
an additional 10·1330·X milion units

= "13,300·X million additional units"

This increase by 13,300·X million units would almost exactly
double the above estimated current world consumption total of 13,200·X
million units

That is, if we start with 13,200·X million units of worldwide
consumption, and add another 13,300·X million units of consumption
(so the new Global consumption total is the sum, or 26,500·X million
units of consumption) then this increase would represent very close to
a doubling.

Notice we needed to include "X" in each number since X is the
per-person (or per capita) consumption in China of the resource in
question; it would have units in barrels if we look at oil; it would
have units in tons or pounds for various metals; etc. [To simplify you
could say replace X by "1" but then your numbers would not be in
barrels or tons but in "multiples of current per-capita consumption"
(e.g. if each person uses (i.e. economic "demand" of) 8 kilograms
copper per year, then if you had an answer of "100 million" you'd need
to multiply by 8 to find out what it meant in actual kilograms]




METHOD #2 for solution:

Let's use C = R·P where C is total consumption, R is the per-capita
(per-person) rate of consumption, and P is population.

Then have a model in which our assumption are:

1)  R-USA = 11·(R-CHINA)

2) (P-China) = 1300 (units: "millions of people")

3) (P-USA) = 300 (same units; we can say "equals" not
"≈" with the understanding this is a Mathematical Model (see
above heading) rather than statements about the real world; had we
done the latter the notation "≈" would be better to use to
indicate numbers are not exact)

In the equations below, let "old" stand for the world and China under
the current per capita consumption in China and let "new" stand for all
numbers, after a hypothetical time in which China has the
same per capita rate
of consumption as the US. Then:

New world consumption 

= ((New China Total Consumption) + (New everyone-else Total Consumption)

= 11·(Old China Total Consumption) + (New everyone-else Total Consumption)
     since we are assuming China's per-capita consumption grows 11-fold but
     its population stays constant, when going from "old" to "new"
     (thus, this would cause it's Total consumption to increase 11-fold)
  
= 11·(Old China Total Consumption) + (OLD everyone-else Total Consumption)
   since no one except China is changing anything in this question.

= 11·(Old China Total Consumption) + [OLD Global Tot-Cons. - OLD China Tot-Cons.]

= [11·(Old China Total Consumption) - (OLD China Tot-Cons.)] + (OLD Global Tot-Cons)

= [10·(Old China Total Consumption)] + (OLD Global Tot-Cons)    [Equation A]

So we just need to convert each of these two parts into numbers.

First, what is (Old China Total Consumption) equal to?
Since C=R·P we have (Old China Total Consumption) = (R-China) · (P-China)    [Equation B-1]


We'll substitute that in, but first, what about (OLD Global Tot-Cons) ?

Well, (OLD Global Tot-Cons) is about 4 · (US Total Consumption) since
we are told we may assume that US consumption is about 25% of global
consumption for many resources. From this we use "C= R · P" again to get:

(OLD Global Tot-Cons) is about 4 · (R-USA) · (P-USA)

But US population is 300/1300 as much as China's so (P-USA) = (300/1300)(P-CHINA)

Substituting this, we get:

(OLD Global Tot-Cons) is about 4 · (R-USA) · (300/1300)(P-CHINA)    [Equation B-2]

Finally we can subsitute equstions B-1 and B-2 into equation A above,
so we transform

= [10·(Old China Total Consumption)] + (OLD Global Tot-Cons)    [Equation A]

into:

= 10· [(R-China) · (P-China)] +  4 · (R-USA) · (300/1300)(P-CHINA)

= 10· (R-China) · (P-China) +  (1200/1300) (R-USA) · (P-CHINA)

= 10· (R-China) · (P-China) +  (1200/1300) · 11· (R-CHINA) · (P-CHINA)

≈ 10· (R-China) · (P-China) +  (10.15) · (R-CHINA) · (P-CHINA)

= (20.15)· (R-CHINA) · (P-CHINA)

And we finally have an expression for  "New world consumption"


But, again, the Old World Consumption was about equal to:

4·(US-Consumption) = 4·(R-USA)·(P-USA) = 4·11·(R-CHINA)·(P-USA)

= 44·(R-CHINA)·(P-USA) = 44·(R-CHINA)·(300/1300)·(P-CHINA)

≈ (10.15) · (R-CHINA) · (P-CHINA)

So putting it all together:
 
    New world consumption would be (20.15)· (R-CHINA) · (P-CHINA)

    versus 

    Old World consumption was: (10.15) · (R-CHINA) · (P-CHINA)

What percent increase when old is "c" and new is "n"? We first divide:
the quotient is equal to (20.15)/(10.15) (the other terms cancel)
which equals 1.98 or about 2. So new is (roughly, many above being
estimates) 200% of the old global consumption. Thus an increase
by 100%; a DOUBLING as claimed. (The above discussion
 could have been simplified a bit by noticing that we merely have to show
 that "additional world consumption" in going from old to new, is
 rougly equal to current ("old")  world consumption, to conclude 
"would roughly double")

No blank spaces are left here because you will probably need at least one blank sheet to paper to think out and work out this exercise. Take a separate sheet of paper which you will either hand in or use for in-class HWP (homework presentations) and/or discussions

If India as well as China were to catch up, world consumption rates would triple. If the whole developing world were suddenly to catch up, world rates would increase elevenfold. It would be as if the world population ballooned to 72 billion people (retaining present consumption rates).

EXERCISE 2: Can you, roughly, justify the "would triple" above? What statistics would you roughly be assuming about India?

No blank spaces are left here because you will probably need at least one blank sheet to paper to think out and work out this exercise. Take a separate sheet of paper which you will either hand in or use for in-class HWP (homework presentations) and/or discussions

India's per capita consumption is less than (is even lower than) China's
India's population is (roughly speaking) about the same, 1.13 billion.
So India consumes LESS than X*1130 (Using notation of Method I)
If it consumed like the US it would reach (11X) · 1130 units.

Thus it would increase world consupmtion by the difference (India's
new minus India's old) namely by more than 10*1130, or 11,300 units; again,
by a number which is roughly the same as the current world consumption total.

It's a bit less than the 13,200 current world total; but 
remember that "an increase by 11,300 million units" is
an under-estimate since per capita consumption in India is less than 
that of China. So "a bit more than 11,300 mil. units" is
even closer to the "13,200 mil. units" that it would take to 
add yet another identical amount to the current total, so not only 
would China consuming at US (per capita) rates (and all else unchanged)
would double world consumption, but if we also imagine India
also moving to US (per capita) levels of consumption would cause the total 
world consumption of the resource(s) in question to triple.

And this would be true under the assumption that nothing else changed:
that is, even if the US did not increase (per capita) consumption, nor
any other country (other than China and India), and
even if world population stayed constant rather than increasing!

More realistic assumptions would include population growth around the
world and at least in the near-to-middle term, and would include an
assumption of an increase in (per person) consumption rates around the
world, not just in India and China. Thus, although longer-term
stabilization of world population seems, fortunately, more likely now
than in the past, and although there are some beginning efforts to
address developed countries' per capita consumption at least in discussion,
in the short/medium term, our numbers would be under-estimates of what would
happen to the entire world's consumption levels were China and/or
India to reach (or even approach) the current consumption level in the
U.S. For some resources (e.g. non-exotic fossil fuels and possibly
"total fossil fuels" such a doubling is either physically impossible
or too expensive, or dangerous to the environment - or all of the
above. Something else has to "give" in such cases. Will we use wise technology
and conservation to reduce our own high per capita rates of
consumption of natural resources? Or will be expect poor countries not
to increase theirs, even if it means expecting them (impossibly) to
accept poverty? Or will we wait until natural limits hit? The "wise
technology and conservation" path seems like the prudent one for
society, even if it's not the convenient one for politicians

EXERCISE 3: What do you make of the "simplifying assumptions" above, "Let's also make things easy by imagining that nothing else happens to increase world consumption -- that is, no other country increases its consumption, all national populations (including China's) remain unchanged and immigration ceases"? What would be the effect on our estimates here were we to use other assumptions? Please explain carefully.

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Solution to Exercise 3 is included with solution to Exercise 2 above

Some optimists claim that we could support a world with nine billion people. But I haven't met anyone crazy enough to claim that we could support 72 billion. Yet we often promise developing countries that if they..institute honest government and [develop economically and open their markets to US businesses] they, too, will be able to enjoy a first-world lifestyle. This promise is impossible, a cruel hoax: we are having difficulty supporting a first-world lifestyle even now for only one billion people.

We Americans may think of China's growing consumption as a problem. But the Chinese are only reaching for the consumption rate we already have. To tell them not to try would be futile.

The only approach that China and other developing countries will accept is to aim to make consumption rates and living standards more equal around the world. But the world doesn't have enough resources to allow for raising China's consumption rates, let alone those of the rest of the world, to [U.S.] levels. Does this mean we're headed for disaster?

No, we could have a stable outcome in which all countries converge on consumption rates considerably below the current highest levels. [The author seems to fail to consider the possibility of moving to lower consumption levels while keeping quality of life the same or higher..but unlike most articles, he does correct this misconception below -Dr. B.] Americans might object: there is no way we would sacrifice our living standards for the benefit of people in the rest of the world. Nevertheless, whether we get there willingly or not, we shall soon have lower consumption rates, because our present rates are unsustainable.

Real sacrifice wouldn't be required, however, because living standards are not tightly coupled to consumption rates [Most articles used the ambiguous term "standard of living" to refer, sometimes, to "quality of life" and at other times, to "level of consumption" as if the two were interchangeable. Jared Diamond's clarification is usually missing] American consumption is wasteful and contributes little or nothing to quality of life. For example, per capita oil consumption in Western Europe is about half of ours, yet Western Europe's standard of living is higher by any reasonable criterion, including life expectancy, health, infant mortality, access to medical care, financial security after retirement, vacation time, quality of public schools and support for the arts. Ask yourself whether Americans' wasteful use of gasoline contributes positively to any of those measures.

EXERCISE 4: What are some ways in which Americans might consume less resources (including but not limited to fossil fuels ) and enjoy either the same or a higher quality of life? And what are some challenges to getting there? Example: "If we lived closer to work we'd have shorter commutes, less time stuck in the car in traffic, and thus arguably higher quality of life while consuming less energy. However, a challenge is that we cannot redesign our entire arrangement -- suburban sprawl, highway system, car-centered transport, etc -- overnight. It would take both money, and years of-- time, to accomplish this" Can you suggest other examples? And be careful to list obstacles/challenges they would entail, if you see any.

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...Just as it is certain that within most of our lifetimes we'll be consuming less than we do now, it is also certain that per capita consumption rates in many developing countries will one day be more nearly equal to ours. These are desirable trends, not horrible prospects. In fact, we already know how to encourage the trends; the main thing lacking has been political will.

Fortunately, in the last year there have been encouraging signs. Australia held a recent election in which a large majority of voters reversed the head-in-the-sand political course their government had followed for a decade; the new government immediately supported the Kyoto Protocol on cutting greenhouse gas emissions. Also in the last year, concern about climate change has increased greatly in the United States. Even in China, vigorous arguments about environmental policy are taking place, and public protests recently halted construction of a huge chemical plant near the center of Xiamen. Hence I am cautiously optimistic. The world has serious consumption problems, but we can solve them if we choose to do so.

Jared Diamond is a professor of geography at the University of California, Los Angeles, and author of Collapse: How Societies Choose to Fail or Succeed