Re: OT Q re Global warming.

On Mar 7, 11:16 am, Kai Haberzettl <kai-use...@xxxxxxxxxxx> wrote:
"Joel" <frokenst...@xxxxxxxxx> writes:
I believe human activity has a minimal effect on the climate. Human
activity has raised CO2 levels from about .03% to .04% of atmospheric
composition. These levels are very, very low compared to most of the
planet's history. Earth has experienced long ice ages with CO2 levels
much higher (10x or more) than they are now. In recent history, Earth
went through a "Medieval Warm Period" where average temperatures were
higher than they are now despite slightly lower CO2 levels. The
variable, cyclic output from the sun, as well as variations in Earth's
orbit and axial tilt are the most important factors in climate change.
Atmospheric composition comes in at a distant fourth, with water being
by far the most important (and consistently unmentioned) greenhouse> > gas. Technically speaking, the scientists aren't lying when they say
CO2 is a greenhouse gas, but what they are doing is overstating its
effects.

http://www.ipcc.ch/SPM2feb07.pdfdisagrees with your "belief" quite
significantly. By the way, what's the source for your assertions? I'd
be particularly interested in your statement that atmospheric
composition is the fourth most important factor in climate change. I
am genuinely curious in how that conclusion has been reached. I'd
appreciate some pointers to relevant research. Thanks.

Kai


Hello Kai,

I've seen this paper before, but I decided to go over it again. I
decided to quote the main points, and I will address them one at a
time:

"Carbon dioxide is the most important anthropogenic greenhouse gas
(see Figure SPM-2)."

True.

"The global atmospheric concentration of carbon dioxide has increased
from a pre-industrial value of about 280 ppm to
379 ppm3 in 2005."

True.

"The atmospheric concentration of carbon dioxide in 2005 exceeds by
far the natural range
over the last 650,000 years (180 to 300 ppm) as determined from ice
cores."

True, but 650,000 years is a grain of sand in the scope of Earth's
history, and as such is an inadequate frame of reference. CO2 levels
have varied from around 180ppm to over 7,000ppm if you expand your
frame of reference to the entirety of Earth's history. Most
importantly, however, we need to discuss the *actual climate* in this
650,000 year time period, not just the CO2 levels. If you discuss the
actual climate (this thread is about climate change, after all), you
will have to account for the Medieval "warm period", for example. This
was when the Earth was warmer than it is now, and it was also when
Greenland was actually green. This is well documented in written
history. If CO2 levels were the primary determinant of climate change,
such an era could not have occurred in such a CO2-impoverished era.
See my other points below.

"Global average sea level rose at an average rate of 1.8 [1.3 to 2.3]
mm per year over 1961 to 2003"

Probably true, although I believe it is probably closer to their low
end of 1.3 mm. Again, the most important question to ask is "why"?
Variation in solar irradiance, in my opinion, is the primary factor.

"Global average sea level in the last interglacial period (about
125,000 years ago) was likely 4 to 6 m higher
than during the 20th century, mainly due to the retreat of polar ice.
Ice core data indicate that average polar
temperatures at that time were 3 to 5°C higher than present, because
of differences in the Earth's orbit."

This is most likely true as well. As I mentioned previously, different
parts of the planet warm and cool differently based on changes in the
Earth's axial tilt. Their own data supports this. Due to increased
solar irradiance of the polar regions 125,000 years ago, there was
melting and the seas were 4-6m higher back then than they are now. I
hope that you can sense the cyclical nature of climate, as well as how
significant the sun really is.

"It is likely that increases in greenhouse gas concentrations alone
would have caused more warming than
observed because volcanic and anthropogenic aerosols have offset some
warming that would otherwise have
taken place. "

In other words, the current theory expected more warming than what was
actually observed. This is the main reason why climatologists are
constantly modifying their computer models - because they have been
unable to make accurate predictions. Most importantly, none of these
climate simulators have been able to "go backwards" and replicate the
previous climates in Earth's history with any degree of accuracy
whatsoever.

"The observed widespread warming of the atmosphere and ocean, together
with ice mass loss, support the
conclusion that it is extremely unlikely that global climate change of
the past fifty years can be explained
without external forcing, and very likely that it is not due to known
natural causes alone."

This is where I disagree, although I only disagree with their sense of
*proportion*. Like I said previously, it is a *scientific fact* that
CO2 traps low level radiation. My point, and the point that I will
continue to make, is that the effects of anthropogenic activity are
quite minimal when compared with the overwhelming force of solar
insolation, orbital eccentricity, and axial tilt. Current global
warming theory fails to account for the fact that the late Ordovician
period (about 450 mya) had CO2 levels of over 4,000ppm (over 10x what
it is today), yet was in one of the coldest eras of our planet's
history - significantly colder then even now. There are other eras
where the exact same thing can be said. There are also numerous
periods where global temperature plummeted while CO2 levels rose
dramatically. How could this happen? How could it be so much warmer
now when there is so much less CO2? I hope you will at least entertain
the possibility that other forces besides CO2 are much more important
in changing the climate.

There are way more articles on solar insolation than I'd care to
reference. You may want to simply google it. If you wish, Kai, you may
email me your questions. I have to get back to work now!

.

Relevant Pages

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