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Doug Miller

In article .com, wrote:
On Mar 8, 7:56 am, (Doug Miller) wrote:
In article .com,
wrote:
I've also found a lot of information indicating net losses of ice
in the Arctic, and a net loss in the world's glaciers, but
information
on the former is not easily converted to net mass so I'm still not
clear on the recent net change, if any, in the global ice inventory.

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 mel****er 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 mel****er 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.

It is also worth noting that I used the term "sea ice" incorrectly.

By definitions, an ice sheet is on land, an ice shelf is ice that has
moved out onto water from a glacier or an ice sheet, and sea ice
forms on water by freezing or precipitation. The Arctic ice cap is
all or nearly all sea ice. Antarctica has all three.

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.

Whether sea levels will rise or fall in response to melting polar ice caps
depends on the relative proportion of submarine Antarctic ice to land-based
ice in Antartica and Greenland.

I've not been able to find data indicating what that proportion is.

Keep in mind also that if you reduce an ice shelf, the associated ice
sheet accelerates toward the sea.

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.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.