Dan Espen writes:
Mark Storkamp writes:

In article , "Bob F"
wrote:

Rebel1 wrote:
I posting this here because there a good analytical minds here.

An experiment: Fill a tall clear glass half-way with ice cubes. Then
add enough water so the bottom cubes no longer touch the bottom
(i.e., they are all floating). Now put a mark at the water level and
wait until the cubes all melt. Did the water rise above your mark?

In my case, it didn't.


[snip]

We can only speculate why Rebel1 thought he knew better than
all the worlds scientists.

But then, Rebel1 claimed "there are good analytical minds here".
(Yes, I laughed so hard, I almost choked.)

Most of these folks see some headline written by a clueless
reporter (often from both sides of the debate) and elaborate
on that, rather than actually digging into the science itself.

There are several contributors to planetary mean sea level (MSL).

- Mel****er from land-based glacial ice
- Fossil water runoff
- Isostatic rebound
- Wind

The first, mel****er from land-based glacial ice
encompasses the high altitude glaciers (e.g. in the
himalayas, upper Rockies, Peru, mt. Shasta, etc), the greenland
icecap and the antarctic icecap.

The second, fossil water runoff is from pumping
geologic water from underground for irrigation and
other human uses. This adds water to the hydrologic
cycle which raises sea level (in fact, this alone is
responsible for something like 40% of the sea level
rise in the 20th century).

The third, isostatic rebound, appears to lower sea
level at certain measuring stations as the land continues
to recover from the weight of a mile of ice 10kya.
A counterpoint of this is areas like southern La., where
the land is sinking due to silting at the mouth of
the mighty muddy.

The largest two regions of land-based ice are the
greenland icecap and the antarctica icecap. In both
cases, the amount of time required to melt 100% of the
ice is measured in thousands of years (note that the air
temperature in antarctica is below freezing for 10 months
of the year). Since the land ice in antarctica is surrounded
by sea ice (which can melt more rapidly as the temperature of
the water it is floating on changes with time, natural cycles
and other forcings), a concern is that if all the sea ice
melts, it will open the way for the land-based glaciers to
flow more rapidly towards the sea and calve bergs, which will
inevitably cause higher sea levels.

As for Wind, certain coastal areas measure higher sea
levels than others due to the wind pushing water towards
the coast (leaving aside any tidal effects).

All this makes it difficult to measure MSL accurately
using surface based measurements. Modern measurements
use satellite altimetry, which generally requires some
amount of correction due to orbital decay characteristics
and instrumental differences beween generations of
measurement satellites.

Current global sea ice area:

http://arctic.atmos.uiuc.edu/cryosph....withtrend.jpg

Current global sea ice anomoly (i.e. difference from average since 1979)

http://arctic.atmos.uiuc.edu/cryosph...aly.global.png

Global, Arctic and Antarctic ice area:

http://www.climate4you.com/images/NS...SeaIceArea.gif

Note that the planet currently has _more_ sea ice than the
average since 1979 (when satellite measurements began). Note
also two years ago, when there was 2 million km2 less.

As others have pointed out, the melting of the sea ice has
effectively no effect on MSL; however it does alter the
albedo of the pole(s) which may reduce the amount of
insolation reflected back to space, leading to
additional warming of the surface water.