In 1798, an English clergyman named Thomas Malthus made a
dire prediction: He said the Earth could not indefinitely support an
ever-increasing human population. The planet, he said, would check population
growth through famine if humans didn't check themselves.
The theory publicized by Malthus is known as the carrying
capacity of Earth. Carrying capacity itself is a well-known and widely
accepted concept in ecology. It's a very basic idea -- sustainability requires
balance. There is a certain population number above which a species starts to
damage its habitat, and life as it stands at that moment cannot go on.
Typically, it's starvation that kicks in to cull the herds down to a manageable
number.
The idea of Earth's carrying capacity goes something like
this: Humans need certain resources to survive at subsistence level -- most
commonly air, food, water and usually some kind of shelter. A
sustainable habitat is one in which supply of and demand for these resources
are balanced. The problem, Malthus suggested, is the difference in growth
patterns between the human population and food production. He said that while
the human population tends to grow exponentially (by a greater amount each year
-- a percentage of the total), the food supply will only grow linearly (by a
fixed amount each year -- a number, not a percentage). In this model, humans
are bound to outgrow the Earth's resources [source: Sachs].
For two centuries, scientists have pretty much dismissed
Malthus' hypothesis, saying he neglected to account for one very important
variable that applies exclusively to humans: technological advancement [source:
Sachs]. They have argued that this human
ability allows food production to grow exponentially, as well. But scholars
have recently begun to rethink their dismissal of Malthus' prediction, for
several reasons.
It seems Earth may have a carrying capacity after all.
So are we doomed? How many human beings can the Earth
support before resources run low and nature takes over, culling the human herds
in order to reestablish a sustainable balance? Or do humans' unique abilities
to develop new food and energy-production methods negate the danger?
Well, it all depends.
What's the Earth's Carrying Capacity?
Carrying capacity is not a fixed number. Estimates put Earth's carrying capacity at
anywhere between 2 billion and 40 billion people [source: McConeghy]. It varies with a
wide range of factors, most of them fitting under the umbrella of
"lifestyle." If humans were still in the hunter-gatherer mode, Earth
would have reached its capacity at about 100 million people [source: ThinkQuest]. With humans
producing food and living
in high-rise buildings, that number increases significantly [source: ThinkQuest].
As of 2008, there were about 6.7 billion people living on
this planet [source: Sachs]. A good
way to understand the flexibility of Earth's carrying capacity is to look at
the difference between the projected capacities of 2 billion and 40 billion.
Essentially, we're working with the same level of resources with both of those
numbers. So how can the estimates swing so widely?
Because people in different parts of the world are
consuming different amounts of those resources. Basically, if everyone on Earth
lived like a middle-class American, consuming roughly 3.3 times the subsistence
level of food and about 250 times the subsistence level of clean water, the Earth could only support about 2
billion people [source: McConeghy]. On the other hand,
if everyone on the planet consumed only what he or she needed, 40 billion would
be a feasible number [source: McConeghy]. As it is, the
people living in developed countries are consuming so much that the other
approximate 75 percent of the population is left with barely what they need to get by.
To the surprise of those scientists who dismissed Malthus'
prediction as fatally flawed, this limit on resources appears to stand despite
the human ability to develop technologies that alter Malthus' presumed linear
growth of the food supply. The issue, then, is why technology isn't saving us
from the disaster of naturally mediated population control.
What are we doing
wrong?
homas Malthus: Right After All?
If we look at the vast advances in food-production technology, known as the green
revolution, we would expect to be able to feed everyone on Earth indefinitely. The more people there
are, the more inventors and advances in irrigation, agriculture, genetic
engineering, pest control, water purification and other methods of
increasing the food and water supply beyond what our habitat would provide
normally. But in fact, food prices are rising at an alarming rate. The problem,
it seems, has to do with the uniquely human byproducts of technological
advancement, like systematic habitat destruction. We appear to be using
technology in a way that defeats the purpose.
The ideal use of technology -- the use that would extend
Earth's carrying capacity -- is to find ways to make fewer resources stretch
much farther. Take, for instance, the Earth's energy resources. Ideally, we
would've switched en masse to technologies like solar power and electric cars
long ago. Instead, we've used technology to simply extract and use more fossil
fuels. So instead of technology allowing us to live better on less, we're
living better on more.
Since oil is a limited resource, and our technologies like
home heating systems and farm equipment still run primarily on oil-dependent
power, when we run out of oil, we potentially
freeze to death in winter and run out of food. At the same time, air and water
pollution resulting from technological advancement is reducing our supply of
even more necessary resources.
So, are we doomed? Not if we make lifestyle adjustments that
get us back into balance with our habitat. Major worldwide shifts to
sustainable energy resources like sun and wind, and a movement toward eating locally grown food, reducing carbon emissions
and even taking shorter showers can help. Mining space for additional resources
might also help us avoid Earth-wide shortages, although that's a far more
uncertain solution to the problem.
Ultimately, the idea is this: If everyone on Earth can manage
to do more with less, we'll be back on track to Earth's indefinite carrying
capacity. Also, since economic development and education tends to lower
fertility rates, spreading modern knowledge to currently under-developed parts
of the world can work as a sort of natural population control, further
extending the lifetime of humanity on Earth.
Newspaper
Reading: Preparation for Group Discussion
Student: LU LIN
1) Select one magazine or newspaper article
to bring to class. This article can also come from an online newspaper
such as The New York Times or The Los Angeles Times.
2) Gather three words you did not
understand, liked, and/or found interesting in the article you selected, look
them up in the dictionary, and complete the table below.
WORD
|
PART OF SPEECH (Noun, Verb, Adjective, Adverb, etc.)
|
· SYNONYM OR DEFINITION
|
1. Capacity
|
None
|
· The amount that can be contained.
· content
|
2. Sustainable
|
Adj.
|
· capable of being sustained
|
3.adjustments
|
None
|
· making or becoming suitable; adjusting to circumstances
· restructuring
|
3) To help with the context for the words you
selected, highlight or underline the sentences that
contain the three words you gathered.
4) In one
sentence, explain what the article is about. You can use the
following sentence starters to help you: “This article is about…” “The main
idea in this article is…”
The main idea in this article is to tell us that the
earth reached its carrying capacity, and it shows us what is earth carrying
capacity and what we should do to
adjustments the earth carrying capacity.
5) Bring
this sheet and a hard or digital copy of your article to class. Be prepared to share
this information with a group of peers next class.
Question:
Question:
Do you agree with Thomas Malthus's prediction? Why?
