Vincent J. Curtis
21 Dec 2018
An unscrupulous climate scientist could try to wave away the
objections of a chemist by saying that the world is not a beaker. The world is not a beaker, but the beaker and
the world follow the same physical laws, and insofar as the world is a beaker,
it must obey the laws as a beaker does.
Of all the con jobs offered by climate alarmist is the one
that says carbon dioxide is the greenhouse gas that is going to drive up the
earth’s temperature by three to five degrees by the end of this century. The major climate models do not, in fact,
say this. They actually say that water
vapor is going to be the villain driving up temperature.
The purpose of this article is to explain simply why this
mechanism can’t happen, and won’t happen; and all it takes to understand why is
some pretty basic knowledge of some chemistry and engineering.
The mechanism of global warming of the climate models is
that higher carbon dioxide content in the air will in turn cause more water
vapor to be present in the atmosphere. And
it is the higher absolute humidity that is going to trap more of heat that
would otherwise radiate into outer space at night, not the carbon dioxide.
Why water vapor?
Water vapor is a far more effective absorber of infrared radiation than
carbon dioxide is. Carbon dioxide, a
linear molecule, has only one mode of absorbing infrared radiation, asymmetric
stretching, and it occurs in a narrow band around 2350 wavenumbers. Molecular bending causes strong, broad absorption to begin at 667 cm-1 and extend into the far infrared. The water molecule is V- shaped, is capable
of hydrogen bonding, and it has three strong and broad absorption bands. (3750
– 3150, 1400 – 1100, and 800 – 600 cm-1)
As explained previously, those who speak of carbon dioxide
and water vapor as “greenhouse gases” don’t know how greenhouses work. Carbon dioxide and water vapor are added to
the greenhouse atmosphere to promote plant growth, not for their heating
effect. Plants need carbon dioxide and water
for photosynthesis, a process which converts these two chemicals into plant
matter using the light from the sun to power the transformation.
Somehow, more atmospheric carbon dioxide is supposed to
cause more atmospheric humidity, sufficient to multiply several fold the magnitude
of the heat trapping effect of carbon dioxide.
So the earth isn’t going to turn into a hot, wind-swept desert, but into
a humid jungle by the end of the century.
The trouble is, the water content of the atmosphere has nothing to do
with carbon dioxide, or indeed, the other gases of the atmosphere at all. The vapor pressure of water depends only on
temperature of the liquid. There is no
chemical interaction between carbon dioxide and water in the gas phase that
would tend to increase the amount of water in the air.
When cold air passes over warm ocean, fog tends to
result. The warm water pumps more water
vapor into the atmosphere than it can hold at its current temperature, and so
the water condenses as fog. The fog
“burns off” when the air warms up and the relative humidity drops below 100
percent. When warm air passes over cold
water, little humidity tends to pass into the atmosphere, though if the air
gets chilled enough, fog, rain or snow can result.
All that matters is the temperature of the ocean and the
temperature of the atmosphere over it. Relative
humidity and absolute humidity interacting.
The other gases in the atmosphere play no role. For the absolute humidity of the atmosphere
to rise permanently, it would require the oceans to warm permanently, and by
several degrees to produce a noticeable effect.
Warmer ocean water would by itself warm the atmosphere above it. Think of a permanent El Nino effect. This isn’t going to happen by some feedback
loop that defies Le Chatelier’s principle.
The results are observable in the climate models. The best of them predicted twice as much
warming as actually occurred since 1998.
The feed-back didn’t happen.
The oceans are the earth’s great reservoir of heat, as well
as of atmospheric humidity. Unlike on Venus, the earth’s atmosphere is
small in mass relative to the oceans and to the planet itself. Because it consists primarily of nitrogen,
the atmosphere possesses internal moderating mechanisms that prevent run-away
temperature changes – quite apart from the moderating effect of the oceans. The moderation of average atmospheric
temperature is quite robust.
For the earth’s atmosphere to experience serious, long-term
changes in condition, which we might call climate change or global warming –
the earth’s ocean in contact with the atmosphere must increase in temperature
by several degrees. That isn’t going to
happen by a feed-back loop involving atmospheric carbon dioxide.
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Vincent J. Curtis is a research scientist and occasion
free-lance writer.
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