Re: Snowball earth, when and why it happened.

Jake <jcbepstein@xxxxxxxxxxx> wrote in
news:1180675650.613010.300480@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:

On 1 juin, 01:52, Earl <nept...@xxxxxx> wrote:


Some background info so that you can understand how
Snowball Earth is a red herring to confuse those opposed to
AGW.



In normal conditions the vast majority of the IR emitted by
the ground is absorbed by water in the first 30 feet.

This comment does not apply to a runaway cooling period when
water is condensing to liquid and then freezing, water is no
longer playing a green house role, only CO2 is left to do
that.

Water plays several roles, the big one is that the earth's
albedo shoots up as the ice coverage expands. The feedback
is different. CO2's solubility increases at the water
temperature lowers but in fact its content in hot and cold
oceans does not vary by a factor of even 2.

The science for a Iceball state with massive ice coverage
is quite real. It appears that we do have two stable states
-- near universal ice and clear ocean. And it does take a
major effort to switch states.

Right, if the weathering lowers CO2 to a low level the
negative feed backs clck in and the system enters a runaway
state. We even see in the glacier-interglacial cyclic a
"runaway" factor, but it is self limiting at the low CO2
levels of the depths of the ice age, it goes no lower. It
could only got lower if more CO2 were removed.

Your "first 30 feet" comment does not apply even today
in the polar regions. Even where it does, the system is
dynamic, there is energy exchange between the earth
and the atmosphere and the energy finally gets out.
The key to the total picture remains CO2, the climate
will not heat up if the CO2 remains constant just
because of the dominate role of water in the energy
exchange between the surface and the atmosphere.


But note a very important point. A near solid cover by ice
means that there is almost zero water in the air (think
antarctica). In fact at the low vapor pressures of water
over ice the effect of water is about equal to CO2 (at
current levels). To get higher water vapor levels you need
open oceans and higher temperatures.

You have that point clear.

At this point CO2 has little effect - the Earth is
regulated by water vapor and cloud cover.

And is in an snowball state. Irreversibly. More water can
not enter the atmosphere unless it heats up, it won't heat
up until that starts to occur.

How how does it get out of it? It can not do this by
by water. The return of CO2 to the atmosphere is necessary
to warm up.





You pretend to be scientificly literate, but refuse to actually
read what is placed in front of you.

If you will actually go back and read what I posted you will
find I discussed each of your points. The snips you posted here
are a firm indication that you only read what you want, and then
misconstrue what is being said.

There are THREE steady state conditions for Earth

Iceball, water surface, and total cloud.

We only have experienced the first two, the third is Venus, a
condition that would occur in a few billion years when
conditions really get hot. Currently the Suns emissions are
insufficient to establish (or maintain) total cloud, regardless
of CO2 levels that are safe to breath. (Venus with closer orbit
and 80 atm CO2 pressure is obviously outside these parameters)

Each condition requires extreme steps for a transition. To
escape Snowball you have to have extremely high CO2 levels --
this is because CO2 is such a minor greenhouse gas. 13%
concentration just to get beyond 32 degree F !!!!

To transition to Snowball you need extreme cold to knock all the
water out of the air. Possibilities are the galactic radiation
levels mentioned elsewhere, massive volcanic eruptions to put a
long term dust cover up to block the sun, or some similar
driving force even more severe than that to trigger a mere ice
age.


But once in place Snowball is maintained by the low H2O vapor
levels over the ice. The CO2 is just inadequate to warm the
Earth in anything but toxic concentrations (and that observation
kills just about all the fantasies of a small CO2 increase
sending conditions runaway. The greenhouse theory is killed by
the iceball data.

But once in a warm water state it is H2O (and only H2O ) that
controls the temperature. It is much like a nuclear reactor
where the rods establish criticality, but once active it is
power levels that controls temperature and criticality.

It is so strange to see the environuts transition from an
absolute love of the Gaia theory and respect for the negative
feedback properties of clouds, to a belief that the only
regulating mechanism for temperature is an out of control
positive feedback from CO2 - a minor component.


You should note a very important point. The ice free arctic
provides the high water vapor to create the massive ice sheets
that brings on an ice age. Only by having an ice free arctic can
you get the snow needed to drop into the deep freeze.

Conditions will cycle, hot then cold. It is after all a system
that bounces around a stable mean. Going to far in one swing and
then reversing.

My personal views are that we have warmed 1 C from the Little
Ice Age, we have another 3C until the arctic melts (or mostly
melts), then we will drop over a 50 year period into a full
blown ice age. And without massive combustion and speading black
dust on the ice that will be the end of most of civilization.
And all the Kyoto accords in the world will not be able to stop
the warm up or ice age. Because even the massive killing of the
western economies was expected to have at most a 2 year delay in
the projections made for temperatures 100 years out. Even the
100% reduction in CO2 emissions wanted by the environuts will
not stop the natural motions of the temperature swings, and you
can't get any higher than 100% reduction.
.

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