[thedoc (OP)]

Jay M. asked the Naked Scientists:
   
How quickly are the icecaps melting and when will they be gone?
What do you think?

[Barry Phipps]

All I know is that the polar ice is melting at an increasing rate, and islands are disappearing and some coastal cities are experiencing flooding during high tides. Miami, for example. It won't be long before a total disaster. This brings up a question: Have any studies been done on how we can deflect heat (or is it radiation?) from the poles, in order to refreeze the water there and prevent sea level rise? Particularly Antarctica. Are any BIG space projects on the drawing board? It might require a gigantic international effort, as I don't know how much work it would require, but I believe it is our last hope. The half-life of the added heat in the ocean is 50 years! Deflecting heat from the poles I don't think is going to solve ocean acidification, but it might save millions of lives by preventing coastal cites from going underwater. 

[alancalverd]

Since the retreating polar ice was actually floating on the sea, according to Archimedes its melting should not increase sea level. Indeed as the ice was previously below 4°C, melting it should initially increase the density of the sea and thus decrease its level.

But who cares about physics and chemistry? Climate change is about politics and original sin. If you choose to live in a coastal swamp, say Miami, it's comforting to blame everyone else when your house gets flooded. 

[puppypower]

One thing that is not taking into account is the dirty snow affect. In the spiring in the north the salt and sand that was used to melt the road ice, begins to concentrate in the snow piles making the snow piles look dirty. This dirtiness causes the piles to melt faster compared to white clean snow. This is due to dirty absorbing sun and clean snow reflecting the sun at the level of IR. As the piles melts the dirty surface area accumulates to get a faster and faster melt.

This may be why the polar caps are not melting as fast and permanently as some of the glaciers. The glaciers melt via the escalating dirty snow affect, while the polar caps melt each summer and refreeze each winter; cleaner snow. The Antarctic Ice is growing. This may be because there is less dirty snow, since most industrial development is north of the equator.

Maybe we should do dirty snow experiments to determine how many PPM of dirt are needed to melt snow twice as fast in the sun at 1C. We can start with one foot of snow wth the dirt uniformly distributed. The dirt gets denser as it melts so the speed of melting will increase with time. 

Below is a picture of a dirty snow pile in spring. It looks like permafrost.

[Tim the Plumber]

Antarctica is gaining ice mass.

Greenland is losing ice mass very very slowly.

Not allowed to post external links () you will have to google "ScienceNordic Greenland has lost 9000 billion tonnes in a century".

9000 billion tonnes of ice loss is less then 10mm of sea level rise.

There are very few other places in the world where any significant ice lies. Significant in terms of 1cm of sea level rise.

[Tim the Plumber]

9000 billion tonnes of ice loss is less then 10mm of sea level rise. 

No it's not, sorry, it's 25mm. Just under an inch. Kept me awake that did.

Still as an excuse the 9000 figure is unlikely to be anywhere near true as the recent figures for 2005 are about 12.9Gt/yr. Since we are presumably in a melting fairly quickly phase today (it being wram) the figure for the century must be at most 1000Gt. Then again I generally find a x10 exageration is the minimum level of lying that the envirnmental groups use.