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The Villain In The Atmosphere
Isaac Asimov
The villain in
the atmosphere is carbon dioxide.
It
does not seem to be a villain. It is not very
poisonous and it is present in the atmosphere in
so small a quantity that it does us no
harm. For every 1,000,000 cubic feet of air there
are only 340
cubic feet of carbon
dioxide--only 0.034 percent.
What
’
s more,that
small quantity of carbon dioxide in the air is
essential to life. Plants absorb
carbon
dioxide and convert it into their own
tissues,which serve as the basic food supply for
all of
animal life (including human
beings,of course). In the process,they liberate
oxygen,which is also
necessary for all
animal life.
But here is what this
apparently harmless and certainly essential gas is
doing to us:
The sea level is rising
very slowly from year to year. The high tides tend
to be progressively
higher,even in
quiet weather, and storms batter at breakwaters
more and more effectively,erode the
beaches more savagely,batter houses
farther inland.
In all likelihood,the
sea level will continue to rise and do so at
greater rate in the course of
next
hundred
years.
This
means
that
the
line
separating
ocean
from
land
will
retreat
inland
everywhere.
It
will
do
so
only
slightly
where
high
land
abuts
the
ocean.
In
those
places,however,where there are low-
lying coastal areas(where a large fraction of
humanity lives)
the water will advance
steadily and inexorably and people will have to
retreat inland.
Virtually all of Long
Island will become part of the shallow offshore
sea bottom,leaving only
a line of small
islands running east to west,marking off what had
been the island
’
s highest
points.
Eventually the sea will reach a
maximum of two hundred feet above the present
water level,and
will
be
splashing
against
the
windows
along
the
twentieth
floors
of
Manhattan
’
s
skyscrapers.
Naturally the
Manhattan streets will be deep under water, as
will the New Jersey shoreline and all
of Delaware. Florida,too,will be
gone,as will much of the British lows,the
northwestern European
coast,the crowded
Nile Valley. And the low-lying areas of
China,India,and the Soviet Union.
It is
not only that people will be forced to retreat by
the millions and that many cities will be
drowned,but much of the most productive
farming areas of the world will be lost. Although
the
change will not be overnight,and
though people will have time to leave and carry
with them such
of their belongings as
they can,there will not be room in the continental
interiors for all of them.
As the food
supply plummets with the ruin of farming
areas,starvation will be rampant and the
structure of society may collapse under
the unbearable pressures.
And all
because of carbon dioxide. But how does that come
about? What is the connection?
It begin
with sunlight,to which the various gases of the
atmosphere(including carbon dioxide)
are
transparent.
Sunlight,striking
the
top
of
the
atmosphere,
travels
right
through
miles
of
it
to
reach the
Earth
’
s surface, where it is
absorbed. In this way the Earth is warmed.
The Earth
’
s
surface doesn
’
t get too
hot,because at night the
Earth
’
s heat radiates into
space in
the form of infrared
radiation. As the Earth gains heat by day and
loses it by night, it maintains an
overall temperature to which Earthly
life is well-adapted.
However,the
atmosphere is not quite as transparent to infrared
radiation as it is to visible light.
Carbon dioxide in particular tends to
be opaque to that radiation. Less heat is lost at
night,for that
reason, than would be
lost if carbon dioxide were not present in the
atmosphere. Without the small
quantity
of
that
gas
present,
the
Earth
would
be
distinctly
cooler
on
the
whole,perhaps
a
bit
uncomfortably cool.