Q1. How much CO2 is in the atmosphere?
They are now reporting the global average CO2 at 375 ppm concentration in
the atmosphere (in 2001). That's a pretty good jump from where it was in
1991 (10 years before): 358 ppm; but about the same rate of increase as
previous decades (about a 5% increase every 10 years).
This site also estimates the amount of carbon in the atmosphere to be
800 billion* tons. That compares with the 7.5 billion tons added every
ten years in my recent post to CCG, (below).
[* If we use a value of 5.137 x 108 kilograms
for the mass of the atmosphere, then 1 ppmv of CO2 = 2.13 Gt (billions of
tons) of carbon. This gives us a value of almost 800 Gt of carbon in the
> " The Earth's natural greenhouse effect keeps the Earth
> 33 � C warmer than it would be without an atmosphere, at an average
> 15 � C. "
Q2. Is it the concentration of CO2 in the atmosphere or the total amount
of CO2 that is in the atmosphere that is most important?
Following is a posted response I made in the yahoogroup listserv
"ClimateConcern" that address this question:
Date: Wed, 19 Feb 2003 17:41:58 -0000
From: "mtneuman <mtneuman@...
Subject: Re: CO2 is the Culprit
--- In ClimateConcern@yahoogroups.com
, "Steve <stevell88@y...>"
> Mike, Mars and Venus are interesting to study since they have
> vastly different climates but very similar atmoshpheric content.
> Mars has a very cold climate with an atmosphere that actually
> freezes. It's distance from the Sun reduces the Suns radiative
> effect however Equatorial areas of Mars receive the same Solar
> energy of Northern Canada or Siberia. Yet, Mars is extremely
> If CO2 were the GHG that it is suppose to be, why would a planet
> with 95% CO2 as an atmosphere and areas with close to the same
> energy as portions of the Earth, be so cold?
MTN REPLY: Because in reality it is the total quantity
(volume/weight) of CO2 in the atmosphere that matters most, not the
percentage of CO2 in the atmosphere. Mars doesn't have much of an
atmosphere anymore. What it has is very thin, and therefore does not have
all that much total amount of CO2 gas in it.
Mars lost most of its atmosphere long ago. When it had a thicker
(heavier) atmosphere, it was warm enough to have running water, as I
said in an earlier post. It had lots more CO2 in its earlier
atmosphere -- that's what made it warm.
> Venus has the same CO2 as an atmosphere but is warm. Now I see
> something strange about this. CO2 is responsible for Venus warmth
> and responsible for Mars being cold. How can that be? Maybe it
> isn't the CO2???
MTN REPLY: First off, to say Venus is "warm" is putting it too
mildly. Venus is very, very hot. Hot enough to melt zinc. 900
degrees F. hot. Burning hot, all the time, uniformly hot over
planet, from pole to pole.
What makes Venus so hot is that its atmosphere is so heavy (very
large volume-wise). I suggest you check out Grinespoon's book "Venus
Revealed" if you want to read more about the depth of the Venetian
atmosphere. Again, it is the total quantity of the greenhouse gases
surrounding the planet that determines how hot or cold the planet
gets, not the CO2 concentration level of its atmosphere.
The atmospheric CO2 concentration is a good measure to tract the
influence of greenhouse gases emitted relative to the atmosphere as a
whole. But it is less important than knowing the total amount of
additional CO2 accumulating in the atmosphere surrounding a planet,
The U.S. emitted 1,883 million metric tons of carbon equivalent gases
in 2001, one-fourth the world total of approximately 753,200,000
million metric tons. Over a ten-year period, this amounts to 7.5
billion more tons of carbon equivalent gases in the atmosphere by
2013, if the annual amount of greenhouse gases emitted by all the
countries remains constant.
Presently, the rate of CO2 concentration in the earth's atmosphere is
increasing at a rate of 15 ppm in ten years. This translates to a
half billion additional tons of CO2 gases added to the atmosphere for
every 1 ppm rise in the atmospheric CO2, other things being equal.
So to return to your question, the atmospheric CO2 (and the other
warming gases present) is responsible for the extremely hot
temperatures on Venus, but not for the colder (relative to earth and
Venus' temperature) on Mars. Mars would be even colder still if its
atmosphere was devoid of CO2 entirely. If it had a thicker
atmosphere like it use to in the ancient past -- one that holds a
larger volume/weight of CO2 above the surface of the planet, then the
planet would be much warmer, like it had to be in the distant past
for water not to freeze.
Q3. Do temperature increases lag behind CO2 increases in the atmosphere
or vice versa?
As to the skeptic's argument that CO2 increases have followed temperature
increases in the past, my analysis of the relationship between those two
has shown just the opposite. My calculations show that right now, today,
the temperatures of Earth ought be 13.1 degrees F. higher than they are
now, based on the historical relationship between CO2 and temperature.
Temperature and CO2 levels in the past have always been highly
correlated, and the earth's temperatures are not keeping up to the rising
concentrations of CO2 in atmosphere now because the CO2 level is
increasing unusually rapidly due to the significantly increasing levels
of fossil fuel burning, mostly in motorized transportation.
By: Mike Neuman, Environmental Specialist, Madison, WI
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