On Mar 8, 4:06 pm, Just Wondering wrote:
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.

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*.

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.

So the only ice that, if melted, would raise the sea level is ice
resting on land masses.

Pretty much so.

When one subtracts out ice on or in the ocean,
how much ice is left, and where is it?

I think addressing that question is part of the ICESAT mission:

http://icesat.gsfc.nasa.gov/intro.html

Also, that's the air temperature
over the land-based ice?

Variable, of course.

Because if the temperature is 20 degrees F,
and global warming raised the temperature to 22, or even 25 degrees F,
it still isn't going to melt.

And let's suppose the prevailing wind blows form west to east
across someplace like Greenland. If the west coast warms
a bit and melts a bit faster that could increase the local humidity
so that the air moving across it sees evaporative cooling and then
more cooling as it rises across the still below-freezing interior.
The result would be a transfer of ice from the coast to the
interior with no net loss and maybe even a short-term net gain
in total ice.

I think that sort of mechanism is the basis for some of the global
warming predictions of greater snow and ice accumulations in some
places.

Regardless, energy is conserved. If the Earth is warming there will
be lat least ONE of the following: less ice and snow, more humidity
or something will have a higher temperature. There is no intrinsic
reason why one or two of those could not remain stable or go the
other way, so long as the other(s) compensated.

The data in the paper I mentioned does not include Antarctic data
past the Spring of 2001. It also excludes some Antarctic ice that
does not affect, directly or indirectly, sea level as the focus of the
paper was on sea level change. Note that ice shelves do not
directly affect sea level but they do influence their associated
ice sheets that do affect sea level.

So if Leon was recollecting a net increase in Antarctic ice and snow
prior to 2002 or a recent increase in precipitation in the interior he
may well be right. That doesn't tell us about net global change,
one way or the other.

--

FF