Trees Make Cents
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Plant a tree : it will keep you warm in winter ,cool in summer,
and help you save money all year round .
Money really does grow on trees. That ’s a message 14-year old Candice
Ray of Mew Haven, Connecticut , could have used when she testified before
Congress two years .
“ I wanted Washington to know my fears about
global warming , pollution , and especially my fears about all the carbon
dioxide in the air,” says Candice, who testified as part of an environmental
campaign called “Beat the Heat .” Her proposed solution : Get people
to care about trees ,Earth’s natural air conditioners and pollution
filters . “Unless more people care about saving trees,” Candice says,
problems like pollution and maybe global warming “will get worse .”
The results of a new study on trees may help
boost Candice’s argument —— and hit members of Congress where they ’ll
feel it : in the wallet . The study , conducted by the U.S. Forest Service
, found that trees make good economic sense . “ Trees can actually save
cities millions of dollars each year by making it less costly to heat
and air-condition buildings, and by reducing air pollution,” says Greg
McPherson of the Forest Service .
If , like Candice ,you want to convince some difficult-to-inspire
adults , here are some facts from the study to back up these claims:
First ,there’s the obvious. Trees provide
shade to help cool us in summer . And they block cold winter winds .
That saves money on air-conditioning and heating bills and the fuel
it takes to power cooling and heating systems .“By planting three mature
trees for shade and windbreak ,”says McPherson, “a home owner can save
$ 50 to $90 per year on air-conditioning and heating costs alone .”,
Over time the money saved would far exceed the cost of the trees .
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All Natural AC
But there ‘s more to the cooling effect of trees than simple shade
.Trees provide natural air-conditioning through a process called evapotranspiration,
or “tree sweating .”
We perspire , trees transpire —— give off moisture when they get hot
. Perspiration and transpiration both produce a cooling effect when
the moisture evaporates —— changes from liquid to gas. Why? Because
this phrase change requires energy.
When you sweat, the energy required for evaporation comes from your
body as heat . So evaporating sweat “pulls’’heat from your body .
But trees don’t have warm bodies like us .So their evaporating “sweat”
pulls heat from the surrounding air .That lowers the air temperature
so you can turn down the AC. Money in the bank !
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OXYGEN PUMP
The coolest part is that while trees are doing all that cooling , they’re
also making the oxygen we need to breathe. The process is called photosynthesis
, a series of chemical reactions trees use to make their food .Basically,
leaves take in carbon dioxide (
) from the air and combine it with water ( )
using the sun’s energy .The products:sugar( )and
oxygen( ).The
reaction looks like this:
Eventually the trees use the energy in the sugar to build new leaves
,branches ,and roots in other words ,to grow .
The more trees grow ,the more energy they
need —— and the more they
produce .Plus, if you look closely at the equation you ‘ll see that
photosynthesis helps use up one of our wastes——
.
We’re not just talking about the
our bodies exhale , but also the many tons of this gas we spew into
Earth ‘s atmosphere when we burn fossil fuels , such as oil and coal
.Without trees the
in car and factory exhaust would accumulate ,or build up , in our atmosphere
.That would be a problem ,scientists say ,because (
along with some other gases ) forms a layer in our atmosphere that traps
the sun’s heat just like a greenhouse ceiling . That ‘s why
is sometimes called a “greenhouse” gas .Some scientists say these gases
could eventually trap so much heat that our entire planet will heat
up.
Trees can help counteract this “ global warming”
by taking in the
and locking it up in the carbon compounds that makes up their leaves
, roots , and trunks .
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POLLUTANT FILTERS
Trees soak up countless other pollutants too , says McPherson —— things
like smoke , ozone ,and particulate matter . “One large ,healthy tree
can save over $2per year in pollution removal,’’ he says . Not impressed
? Try multiplying to see how much money 2000trees would save a city
: $4000.
Of course , adds McPherson , “trees can become stressed if pollution
levels get too high .”and stressed –out tress won’t do any of their
jobs well .
Which brings us back to Candice’s bottom line : “We need to take care
of trees and keep them healthy , so they can keep us healthy ,” she
says . “With more trees,we ‘ll have cleaner ,fresher air to breathe
,and a healthier planet to live on .’’
From Science World , Nov .18, 1994 .
Approximately 800 words
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