EarthTalk: Do you have current facts and figures
about how much rainforest is being destroyed each day around
the world, and for what purpose(s)?
-- Teri, via e-mail
losing upwards of 80,000 acres of tropical rainforest
daily, and significantly degrading another 80,000
acres every day on top of that, mostly due to activities
such as commercial logging, agriculture, cattle ranching,
dam-building and mining. Pictured: a section of Amazon
rainforest is cleared by burning.
© Getty Images
down exact numbers is nearly impossible, but most experts
agree that we are losing upwards of 80,000 acres of tropical
rainforest daily, and significantly degrading another 80,000
acres every day on top of that. Along with this loss and
degradation, we are losing some 135 plant, animal and insect
species every day—or some 50,000 species a year—as
the forests fall.
to researcher and writer Rhett Butler, who runs the critically
acclaimed website, Mongabay.com, tropical rainforests are
incredibly rich ecosystems that play a key role in the basic
functioning of the planet. They help maintain the climate
by regulating atmospheric gases and stabilizing rainfall,
and provide many other important ecological functions.
are also home to some 50 percent of the world’s species,
Butler reports, “making them an extensive library
of biological and genetic resources.” Environmentalists
also point out that a quarter of our modern pharmaceuticals
are derived from rainforest ingredients, but less than one
percent of the trees and plants in the tropics have been
tested for curative properties. Sadly, then, we don’t
really know the true value of what we’re losing as
we slash, burn, and plant over what was once a treasure
trove of biodiversity.
to the United Nations’ Food and Agriculture Organization
(FAO), overall tropical deforestation rates this decade
are 8.5 percent higher than during the 1990s. While this
figure pertains to all forests in the world’s tropics,
researchers believe the loss of primary tropical rainforest—the
wildest and most diverse swaths—has increased by as
much as 25 percent since the 1990s.
increased public awareness of the importance of tropical
rainforests, deforestation rates are actually on the rise,
mostly due to activities such as commercial logging, agriculture,
cattle ranching, dam-building and mining, but also due to
subsistence agriculture and collection of fuel wood. Indeed,
as long as commercial interests are allowed access to these
economically depressed areas of the world, and as long as
populations of poor rural people continue to expand, tropical
rainforests will continue to fall.
scientists see light at the end of the tunnel. Joseph Wright
of the Panama-based Smithsonian Tropical Research Institute
says the tropics now have more protected land than in recent
history, and believes that large areas of tropical forest
will remain intact through 2030 and beyond: “We believe
that the area covered by tropical forest will never fall
to the exceedingly low levels that are often predicted and
that extinction will threaten a smaller proportion of tropical
forest species than previously predicted.”
time will tell whether Wright’s optimistic predictions
ring true, or whether a more doomsday scenario will play
out. To stay informed and be part of the solution, stay
tuned to the websites of Rainforest Action Network, Rainforest
Alliance, the Rainforest Site and, of course, Mongabay.com.
Action Network; Rainforest
EarthTalk: I recently saw a reference to “Enertia
houses” that require little in the way of external
sources for heating or cooling. Do you have any information
on this housing design?
-- Alan Marshfield, via e-mail
homes marry the concepts of geothermal and passive
solar heating/cooling into what amounts to a highly
energy efficient hybrid system. Pictured: a two-story
© Enertia Building Systems
Enertia is a
brand name for homes designed and sold in kits by North
Carolina-based Enertia Building Systems (EBS). The idea
essentially marries the concepts of geothermal and passive
solar heating/cooling into what amounts to a highly energy
efficient hybrid system. Architectural inventor Michael
Sykes coined the term “Enertia” in the 1980s
to describe the innovative homes he was designing that would
store solar and geothermal energy and make use of it for
most if not all heating and cooling needs.
Under such a
system, solid wood walls replace siding, framing, insulation
and paneling, while an air flow channel—or “envelope”—runs
around the building inside the walls, creating what Sykes
terms a miniature biosphere. Inside the envelope, solar
heated air circulates, pumping and boosting geothermal energy
from beneath the house and storing it within the wood mass
of the walls, where it is doled out gradually.
the properties of thermal inertia—the ability of materials
to store heat and give it off slowly—an “Enertia”
house maintains a relatively fixed and comfortable temperature
throughout the warmer day (when solar heat is collected
and stored) and cooler night (when the wood walls give off
heat to keep things toasty as the mercury dips).
The heart of
the system is a south-facing sun space within the envelope
that is dominated by windows and which therefore soaks up
lots of solar energy, filling the house’s wood walls
with thermal energy that in turn radiates into the primary
living space. The entire house functions like an electric
heat pump—moving warm and cool air around to accommodate
the comfort needs of the occupants. It works even throughout
the seasonal changes of the year—with minimal to no
fossil fuels consumed or pollution generated.
In one Enertia
house in North Carolina, the only power bill the owners
typically pay is $35/month for electricity. They also have
a back-up in-floor radiant heating system powered by natural
gas for long cloudy stretches or unusually cold weather.
Gas bills for heat typically total $150 for the year, meaning
the owners’ total annual outlay for heating, cooling
and electricity is less than $600—some $1,000 less
than traditional homes in the same zip code are paying,
according to data from the U.S. Department of Energy.
EBS markets several
different designs for its Enertia houses, but all share
the basic premise of primary interior living space heated
and cooled by air channeled in from a south-facing “buffer
zone” envelope and from below grade. Smaller houses
in the line top out at about 2,000 square feet over two
floors of living space, while larger ones encompass some
4,000 square feet of living space over three floors. Depending
on the model, you could spend anywhere from $66,000 to $292,000
for a complete plan and building materials kit. The rest—including
the selection and cost of the land and the labor to build
the house—is up to you.
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