http://www.commondreams.org/headlines03/0114-04.htm
Published on Tuesday,
January 14, 2003 by OneWorld.net
Smaller Households Lead to Vanishing Biodiversity
by Cat Lazaroff, ENS
WASHINGTON - A worldwide trend toward smaller households is fueling
a global housing boom and threatening biodiversity around the
world,
a new study finds. The report is among the first to link trends
such as a rising divorce rate and a movement away from
multigenerational households to changes in resource consumption
and sprawling development.
Even where the human
population is declining, the number of
households continues to grow, concludes the study by scientists
from Michigan State (MSU) and Stanford Universities. The results,
the authors say, point to needed changes in policies intended
to protect valuable wildlife habitat and ecosystem services.
"Having
fewer people in more households means using more
resources and putting more stress on the environment,"
said Jianguo "Jack" Liu, an associate professor of fisheries
and wildlife at MSU. "Freedom and privacy come at a huge
environmental cost."
According to
the study, housing units throughout the world
are being built at a rate that outpaces population growth,
resulting in a loss of habitat, natural resources and
biodiversity.
"We had
hoped to find that, where human population growth
was slowing, biodiversity might be given some breathing room,"
said Stanford University ecologist Gretchen Daily, a co-author
of the study. "But instead, we've found that urban and
suburban sprawl are accelerating faster than population
growth is decelerating."
"To our knowledge,
this is the first study to look at
the environmental impact of households on a global scale,"
Daily added.
Liu, Daily, and Stanford
population expert Paul Ehrlich
and postdoctoral associate Gary Luck, examined household
dynamics and population changes in 141 countries worldwide,
then scrutinized six areas with biodiversity hotspots:
areas with high densities of animal and plant species.
The studies paint pictures
of how changes in human lifestyles
affect different habitats - from endangered pandas in the
mountains of southwestern China to the subdivisions that
press against the Florida Everglades.
The researchers found
that across the world, in both developed
and developing countries, households are getting smaller,
and there are many more of them. Multigenerational living
arrangements are giving way to couples or individuals moving
out on their own.
Rising divorce rates
mean families that used to live in
one dwelling now occupy two, and aging populations mean
more parents living in households separate from their
grown children.
The result is often
urban sprawl and less efficient housing
for the same number of people. For example, a refrigerator
uses about the same amount of energy whether it belongs
to a family of four or a family of two.
Each household takes
up space, requires resources to construct,
and fuel to heat and cool it. Increased energy consumption
also increases the emission of greenhouse gases, which is
believed to contribute to global warming.
"In larger households,
the efficiency of resource consumption
will be a lot higher because more people share things,"
Liu said. "Usually, many people will share living space
and other resources. This is true in all countries."
While households may
be shrinking in number of residents,
most are growing in terms of square footage. Fewer people
tend to live in more space.
For example, in Indian
River County, Florida, the average
area of a one story, single family house increased 33 percent
in the last three decades, from an average of about 1,800
square feet in houses built before 1970 to an average of
about 2,400 square feet built between 1970 and 2000.
"Had the average
household size stayed at the 1970 level,
Indian River County would have had 11,000 fewer households
in 2000," the researchers observed.
The household project
grew from Liu's years of research
on how humans interact with fragile wildlife habitat
in China's Sichuan Province, where villagers compete
for resources with the endangered giant panda. In Wolong,
Liu learned, a reduced average household size was tied
to an increase in household numbers and a rise in the
amount of fuel wood consumed by the local populace for
cooking and heating, which has contributed to deforestation
and loss and fragmentation of habitat for giant pandas.
"The numbers of
households increased much faster than
the size of the population at Wolong," Liu said.
"What was discovered from the panda reserve helped me
to conclude that considering population size and growth
alone is not enough, and made me want to find out
whether other areas in the world have similar phenomena."
"The issue of
the number of households and their impact
on the environment basically has been ignored. It was even
difficult to unearth the data," Liu added. "Everyone
looks at population size and growth rate, but the number
of households and household size are crucial factors
affecting the environment."
The team of researchers
found that in 76 countries containing
biodiversity hotspots, between 1985 and 2000 the number of
households grew by 3.1 percent a year, whereas the population
increased only 1.8 percent. Meanwhile, the number of people
living in a single dwelling dropped from 4.7 to 4.0.
The scientists estimated
that had average household size
remained the same in hotspot countries during the 15 year
period, there would have been 155 million fewer households
overall, meaning less pressure on biodiversity. Hotspot
countries studied included Australia, India, Kenya, Brazil,
China, Italy and the United States.
"Ignoring population
growth, reduction in household size
alone is projected to add 233 million households to hotspot
countries between 2000 and 2015," said Daily.
In the 65 non-hotspot
countries, similar trends were found,
although the magnitudes of change were less. In 1985, the
average household size was 4.7 in hotspot countries and 3.7
in non-hotspot countries. By 2015, the average household
size in hotspot countries is expected to be 3.4 persons,
and in non-hotspot countries, it is expected to be 3.6 persons.
Liu contends that the
increase in household numbers even
in non-hotspot countries directly influences important
biodiversity on a national and local scale. Indirectly,
he says, global environment is affected in such patterns
as more energy consumption and release of more greenhouse
gases.
Even in regions where
population size decreased, such
as in New Zealand, the number of households increased
because of a reduction in household size.
The "double toll"
a reduction in average household size
takes on the environment, the scientists said, includes
more land use and more materials consumed for construction,
and a lower efficiency of resource use per person.
In hotspot countries, where this trend is most prevalent,
the authors believe there may be severe limits on efforts
to conserve species, thus "degrading the ecosystem services
that biodiversity delivers to humanity."
In the past, the business
community took most of the
heat for many environmental problems, Liu explained.
"While there is
still a need to reduce pollution and
ecological destruction caused by factories and companies,
this study provides a wake up call, and suggests that
efforts at the individual and household levels are also
needed to reduce impacts on the environment," Liu said.
Changes in government
policies such as tax incentives
for sharing housing and resources could be helpful
to influence personal and household decisions and
actions, he added.
"In China and
many other countries around the world,
incentives created to help the environment are based
on households," Liu said. "These incentives have good
intentions, but they also encourage households to break
into smaller households."
The threat to global
biodiversity is likely to escalate,
the authors concluded, because current household trends,
such as higher divorce rates and increased affluence,
are expected to continue.
"Most countries
containing hotspots have relatively
low population growth rates, and the primary demographic
pressure on their biodiversity will come from urban sprawl
and other impacts associated with increased household
numbers," they wrote.
"We all depend
on open space and wild places, not just
for peace of mind but for vital services such as crop
pollination, water purification and climate stabilization
that are key to health and economic prosperity," Daily
observed.
"The alarming
thing about this study is the finding that,
if family groups continue to become smaller and smaller,
we might continue losing biodiversity - even if we get
the aggregate human population size stabilized."
The research, funded
by the National Science Foundation
and the National Institutes of Health, appears in the
January 12 online edition of the British science journal
"Nature."
Copyright 2003 OneWorld.net
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