MODERN TIMES
Art Hobson
ahobson@uark.edu
http://physics.uark.edu/hobson/
NWA Times 24 Oct 2009
Overpopulation and
excessive immigration spell trouble.
The
planet is getting into serious trouble.
Evidence of this is all around.
For
example, the September 24 issue of the leading scientific journal Nature featured an article titled "A safe operating
space for humanity," by 29 internationally known authors. The article identifies ten planetary
boundaries that, if transgressed, could cause unacceptable environmental
change. The boundaries include
three that humans have already transgressed: greenhouse gas limits, species extinctions, and interference
with the nitrogen cycle. The
others, where current trends are pushing us toward dangerous conditions, are
interference with the phosphorus cycle, stratospheric ozone depletion, ocean
acidification, freshwater consumption, excessive land cover converted to
cropland, atmospheric aerosols, and pollution by long-lived chemicals.
It's
remarkable that human population growth drives every one of these trends. For the past two centuries, that growth
has proceeded catastrophically.
Although it took 7 million years for human numbers to reach one billion
in 1825, we reached two billion just one century later, six billion in 1999,
and are headed toward 9 billion by 2050.
Although this is far beyond the planet's estimated 2 to 4 billion
carrying capacity, we continue to reproduce like rabbits.
As
concrete examples, groundwater in northern India, northern China, and the
American high plains is seriously and unsustainably declining due to overuse,
with ominous implications for food supplies.
A
recent paper titled "Reproduction and the carbon legacies of
individuals," published in the peer-reviewed journal Global
Environmental Change, provides a unique
perspective on human reproductive choices. It estimates the extra emissions of carbon dioxide (CO2,
the main cause of global warming) that an average individual indirectly causes
by choosing to have children. In the
U.S., an average individual, during his or her lifetime, causes the emission of
about 1600 tons of CO2.
But reproductive decisions result in added indirect emissions of over
9000 tons of CO2 per child.
The reason for this large number, nearly six times larger than one
individual's lifetime emissions, is that each child will, on average, have
children, and their children will have children, and so forth. "Weighting" each future
generation appropriately to take into account that each first generation child
came from two parents, each second generation child came from four
grandparents, and so forth, we get the long-term multiplier effect of nearly
6.
Because
different nations have different per-capita lifetime CO2 emissions
and different per-capita numbers of children, each nation has a different
per-child carbon legacy. For
example, one Chinese individual's lifetime emissions are 300 tons of CO2,
while indirect emissions due to reproductive decisions are 1400 tons per child.
So
decisions about how many children to have are surprisingly important for the
environment. For example, whereas
each American can reduce his or her lifetime CO2 emissions by 150
tons by deciding to drive a car getting 30 miles per gallon instead of one
getting 20 mpg, he or she can reduce their indirect emissions by 9000 tons by
deciding to have two children instead of three. Your biggest environmental decision is the number of
children you will have.
In
this day and age, the moral decision is surely to stop at two. This guideline wasn't as clear in the
past so we shouldn't be critical of past generations, but today it's
unmistakable.
Still
thinking about CO2 emissions, each American-born child represents
eventual emissions of 9000 tons, whereas each Chinese child represents only
1400 tons. Each American child is
a kind of environmental disaster for the world, because Americans consume so
much. In this sense, the United
States is the world's most overpopulated nation.
This
argues strongly against continued high levels of immigration into the United
States. The U.S. population growth
rate is nearly one percent per year, an outlandish rate more akin to developing
nations than to other rich nations.
But two-thirds of the U.S. growth is due to immigrants and their first-generation
children. This addition to the
U.S. population is a disaster for the world because of each American's heavy
environmental impact. It's also a
disaster for America where rampant population growth drives a host of social
problems. And it's a disaster for
other nations such as Mexico, because most immigrants are good working people
looking for a better life--just the people that developing nations need. Finally, the present massive illegal
immigration harms the immigrants themselves, who are often cut off from family
members, discriminated against, and exploited by employers.
The
fair and humane way to stop most illegal immigration is workplace
enforcement. There's surely some
system of worker identification that preserves civil liberties while stopping
the employment of illegal immigrants.
Yet the Arkansas legislature recently defeated a bill to penalize
building contractors who knowingly hire illegal immigrants. It's instructive to note that employers
opposed the bill, while labor supported it. Illegal immigrants mean bigger profits for employers but
fewer jobs and lower pay for working people.
It's
encouraging that total legal and illegal immigration dropped from 1.8 million
in 2006 to 1.5 million in 2007.
This is still far too many immigrants, but it's an improvement that's
been brought about by stepped up enforcement of immigration laws.
The
world, and especially the United States, needs to follow their brains instead
of their feelings in matters regarding human population. The world is bursting at the seams, and
the United States is the worst offender.
A good place for the world to begin is by adopting "stop at
two" as a moral code for the modern age. A good place for the U.S. to begin is by reducing legal and
illegal immigration. Immigrants
are wonderful people, but their numbers are too large.