Interesting north south sea ice asymmetry developing

[n2doc]

Those who have been following the sea ice threads posted at DU know the northern ice cap shrunk to an all time minimum this year:



But what you might not have seen is that the Southern sea ice extent has been unaffected:



even though there is evidence of melting in Antarctica's land-ice.

Not sure what it means, other than any climate change associated with sea ice coverage is going to be concentrated on the Northern hemisphere.

[Richard D]

1. More politicians . . .

. . . spewing hot air in the Northern Hemisphere?

[Lerkfish]

2. maybe because we haven't entered winter in the northern hemisphere yet

and when that happens, the southern hemisphere tilts more towards the sun for their opposite summer to our winter.
We may yet see similar data for the southern hemisphere a year hence

[TechBear_Seattle]

3. There is a very big difference between the north and south pole ice caps

The one at the North Pole sits on water. The one on the south sits almost entirely on land.

The oceans are warming faster than the atmosphere, which means the North Pole cap is being melted at both the top and bottom at the same time. The South Pole cap sits on solid rock, which is much less subject to ambient temperature change.

As the North Pole cap melts, it exposes open ocean with is dark relative to the ice. The dark water absorbs more heat, heating it further, which accelerates melt, which exposes more water, which gets warmer, etc. The warmer water is free to circulate, which accelerates melt not only at the edges of exposed water but underneath the ice as well. As the South Pole cap melts, it exposes rock which has a higher albedo than ocean water, so it does not get as warm as fast. Because it is solid, the heat stays fairly local rather than circulating.

So all in all, it would be much more surprising if the South Pole ice cap were melting as fast as the one at the North Pole.

[jebediah]

4. Or we'll develop an exaggerated precessional wobble that'll eventually

flip us around into a multi axis spin. The sun will range all over the sky and the seasons will be gone. Polar and equatorial climates will average across the hemispheres. Don't even get me going on the magnetosphere.

So, if that made any sense, note that you heard it here first.

[phantom power]

5. Interestingly, it is our moon that stabilizes our axis of rotation.

The mass of the ice-caps is pretty insignificant as a fraction of the earth's total mass.

[jebediah]

7. that is interesting. Is that assumed for other planets? Does Saturn, for example

owe its rotational stability to the moons? If not, how is that accounted for?

(Well, I guess I've assumed that Saturn has a stable rotation.)

[phantom power]

9. At least some other planets do not have stable rotational axes. Mars does not.

Its moons are too small. I don't know about the gas giants, although Uranus has an axis pointed nearly into the ecliptic, and I bet thats an indication that its axis isn't stable.

Mercury is tide-locked with the sun. My guess is that stabilizes its rotation. I don't know about venus.

[jebediah]

10. So, the Mars polar regions aren't permanent? What sort of period are we talking about?

The current polar regions seem to have been intact long enough to keep the water ice. Or is the idea that the water ice migrates to the existing poles?

[phantom power]

11. I cannot find any description of periodicity.

Weather on a planet like that would be pretty crazy. Poles would not function in the way we're used to, as reliable heat-sinks. I'm not sure how much Uranus is affected, since it's distance from the sun may makes its orientation irrelevant. For us and Mars, solar heating dominates our weather, but the sun is practically another star from Uranus.

[skids]

12. Ooh. I like your new avatar! n/t

[phantom power]

13. Thank you! If you like that...

you will probably dig this:

http://www.aleph.se/andart/archives/2006/10/index.html

Scroll down to this entry: October 07, 2006

[skids]

14. Happy birthday...

...I think this will fit within the DU avatar upload constraints:



(Yeah I know, it spins the wrong direction. I noticed that after I finished. Doh.)

[phantom power]

15. Cool. And the text is easier to read.

:hi:

[jdlh8894]

6. In other words,

the elipse is a sphere,or the sphere is an elipse?

[jebediah]

8. You've made me think of the equatorial bulge, which of course would have to change

with a chaotic rotation. So, add massive earthquakes to my scenario. And tidal chaos as well.