Re: If this is global warming...

On Mar 9, 8:06 am, spamb...@xxxxxxxxxx (Doug Miller) wrote:
In article <1173392660.592991.292...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, fredfigh...@xxxxxxxxxxx wrote:
On Mar 8, 7:56 am, spamb...@xxxxxxxxxx (Doug Miller) wrote:
In article <1173332788.232048.276...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
fredfigh...@xxxxxxxxxxx wrote:

...

It's worth noting that, whatever the effects of loss of ice in the north polar
cap may be, rising sea level is *not* among them: the north polar cap is
floating, and melting all of it won't affect sea level.

Not entirely correct because the meltwater is freshwater that is less
dense than the seawater displaced by the ice. But you are correct
in that effect is very small compared to the effect of an equal mass
of ice melting on land.

The difference in density between the meltwater and the ocean water won't
amount to a hill of beans. Yes, ocean water is more dense (by 2.7%), but
there's also a whole lot more of it, too, and the fresh water isn't going to
just lay there on top of it, either. Once it's mixed in, there won't be a
noticeable effect.

I don't think it matters whether the water molecules are
all in one blob or distributed over the entire ocean. So
the effect would be 2.7% of the volume of the meltwater
which we agree is not significant.

...

The south polar cap is an entirely different story. Some Antarctic ice is
floating; some of it is on land, above sea level; and some of it is on land
*below* sea level -- that is, it's in the ocean and resting on the ocean
floor. Melting of ice in this last category will cause sea level to *drop*.

Does the ice in that category extend from the ocean floor to some not
insignificant height above mean sea level?

If it does, I can't find any indication of it in either of my world atlases.


NASA probably has the data. Unfortunately net-vandals have forced
NASA into computer security practices that make it harder to get
the data out of the Distributed Data Archives free access to which
NASA was trying to provide to the world. It is hard to overestimate
the damage done to the world by spammers, crackers, and other
net-vandals.


...

My interest is not in estimating sea level change, but in estimating
the energy gained or lost by the phase change. That is to say,
isothermal warming or cooling.

Hmmmm.... now that's an interesting thought. Hadn't considered that
perspective. Certainly, the ice absorbs heat as it melts -- a lot of heat (80
calories per gram) -- whether that's significant on a planetary scale may be a
different matter.


I think that a comparison with how much the air temperature would
rise or fall if all of the heat were lost or absorbed by the air alone
might
be instructive.

Of course the latent heat of evaporation and the high heat capacity
of water overwhelms that. Small global changes in humidity or ocean
temperature absorb or emit huge amounts of heat. That is a real good
thing as it provides us with stability. It also make it devilishly
difficult
to tell if the Earth is warming or cooling and at what rate, without
very long observation, unless the rate is dangerously large.

--

FF

.

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