On Sat, Dec 01, 2012 at 09:03:35AM -0500, Roger Clough wrote:
Hi Russell Standish
Be that as it may, even a study over the last millenium
would be based on inadequate data compared to the
data from the Vostok ice cores. The hockey stick data
used by Gore and others could possibly be a real change,
but it pales in comparison:
so there is some undetermined cause of these cycles which occurred long before
automobile or industrial production. There is a theory based on earth's
inclination or wobble called
the mikhailovich cycle, but the periodicity, although close, doesn't match.
As I understand it, state of the art understanding has it that the
Milankovitch cycle is the initial cause of the cyclic variation in
glaciation, is not sufficient in itself to generate the temperature
variation. Rather, various positive feedbacks amplify the Milankovitch
cycle into the large glaciation cycle. That would also explain why the
period doesn't match exactly.
My own belief (not original) is that the CO2 is expelled and redissolved from the
vast reservoir of
the oceans as temperature varies. C)2 is much more soluble in cold water.
Yes, that would another +ve feedback. But a rather minor one, I
suspect. A 2-5 degree temperature variation out of 300 degrees (room
temperature on the Kelvin scale) doesn't sound like it would change
CO2 solubility by much. By contrast, we've seen a near doubling of CO2
concentration since preindustrial times, which doesn't seem
explainable from ocean temperature trends.
So why is the arctic ice melting but in contrast only melting
slightly at the southern pole ?
Well, it is melting a bit more than slightly in Antarctica, mostly in
the Antarctic peninsula. Many of the glaciers in West Antarctica have
accelerated, just as they have in Greenland. By contrast, East
Antarctica seems stable, which is just as well for us humans.
In the arctic, there is a strong +ve feedback from the fact that open
ocean has lower albedo, so absorbs more sunlight during summer,
heating the ocean, and preventing buildup of ice during Winter. By
contrast at the South Pole, the ice sheet is some 3km thick - it will
be a long time indeed before the ice has melted enough for the albedo
effect to start accelerating things.
It may be related to El Nino and La Ninja, which are unevenly distributed. I
believe El Nino
(which is associagted with warming and is now present) is the cause of north pole
El Nino is associated with warming of the ocean off South America, and
corresponding cooling of the Coral sea. It causes droughts in
Eastern Australia, and rain in Chile. La Nina is the reverse situation. It
causes a lot of rain here in Australia, and somewhat cooler weather. I
thought we were still in La Nina (we had a lot of rain last year), but
I see the current value of the ENSO index is neutral - neither El Nino
nor La Nina.
I would assume that polar warming would be more influenced by the Artic
Oscillation than ENSO. I'm not sure how connected the AO is to the
But, I don't claim any expertise in these matters :)