Jeff Liebermann wrote:
On Sat, 1 Oct 2011 17:30:35 +1000, "Trevor Wilson"
wrote:

http://802.11junk.com/jeffl/crud/Vostok_Petit_data_03.jpg

**I've studied the graphs in some considerable detail over the years
and have noted that CO2 rise sometimes precedes temperature rise and
sometimes it lags. This fits in well with current theory on how
temperature changes have occured in the past. Not all have been
caused by CO2 rise. The most important factor to note, however, is
that CO2 levels and temperature levels track each other very
closely. When one goes up, the other does too.

You can't have it both ways.

**Of course you can. High CO2 levels lead to rising temperatures. High
temperatures drive CO2 out of solution from the oceans. When one rises, the
other follows.

Either warming causes a CO2 increase, or
CO2 causes a warming increase.

**Of both.

Since they track each other, it's
presumed that there's a cause and effect mechanism in operation.

**Well, we KNOW that CO2 acts as a GHG. That has been shown experimentally
many times.

If
your claim of mutual causality were true, where an increase in either
factor causes an increase in the other, then that's positive feedback.

**Correct.


Temperature and CO2 would simply increase without any limit, causing
the planet to look like Venus.

**Not necessarily. We don't have as much CO2 available as there is on Venus,
for instance. We also don't know precisely what caused prior warmings or
high CO2 levels. We are also much further out from the Sun than Venus is.
Make no mistake: The Sun is the major driver of temperatures on this planet.
CO2 is a relatively small driver. It is NOT an insignificant driver.

We've survived 5 temperature cycles in
the last 500,000 years which demonstrates that it's NOT postive
feedback.

**Not quite. The prior warming periods occured over many thousands of years.
This present warming is occuring within a few hundred. It is occuring MUCH
faster that at any time in the past few hundred million years. It is the
extreme rapidity of the present warming that is causing considerable
concern.


http://rps3.com/Files/AGW/VOSTOKICECoreObservations_Stewart2009.pdf
Assuming the five temperature maximums are related to the 1st
Order 100,000 year Milankovitch cycles, CO2 had little effect
is maintaining the high temperatures. As seen in Cycle 4,
even though CO2 levels were at maximum 299 ppmv CO2,
temperature did not continue to increase, but actually made
a abrupt reversal. Therefore it appears that the mechanical
temperature rise & fall associated with 1st order Milankovitch
cycles appear to overwhelm any warming effect associated with
CO2, for CO2 levels below 299 ppmv;

**Except that CO2 levels are presently around 385ppm and rising. As is
average temperature.


--
Trevor Wilson
www.rageaudio.com.au