Sunday, March 22, 2009

Hey Wait A Minute!

If I put ice cubes in my water, they float. They float because they displace water equal to their mass, and water being more dense than ice, up they go. When my ice melts it exactly replaces the water formerly displaced and the water level in my glass doesn't change one bit.
So, if we warm the globe enough to melt off ALL the arctic sea ice, how does that raise the level of the ocean one bit? Land based de-glaciation I get, but that's a really small percentage of arctic ice. What am I missing here?


Lee said...

Tidal volume. Because the entire water level is not a constant across the world the introduction of more liquid mass means a higher fluctuation of water levels would be possible.

An entire overall rise in sea level? Nope.

flyingvan said...

I don't buy it. What form the water is in is irrelevant to its distribution, I believe.

- Rob said...

I haven't "done the math", but the claim is that the movement of a large amount of the water on the planet that is not in the oceans currently (such as land based snow and ice and water in the atmosphere) will add a significant amount of volume to the water currently in the ocean.

I personally have not done any research to see if this is reasonable. However, I do remember that the Earth is somewhere around 70% ocean and so an awful lot of extra water would be needed to make a significant impact.

I bet there are people on both sides that have done this research. I am guessing that there are conflicting theories on this.

What I like about this is that with enough time the theories should stabilize and approach some sort of consensus. That is if the "debate is over" and the "GW alarmists are idiots" crowds do not squelch the discussion. In my mind, the most important thing right now is to make sure that the discussion runs a natural course.

shoo said...

On Greenland and Antartica, there are ice sheets literally thousands of feed thick. If those melt and slide into the ocean, then that causes the huge sea-level rise people are concerned about.

Artic ice: you are dead on. No net gain in sea level.

flyingvan said...

I poked around a bit. 3% of the erath's surface is covered with land with ice on it. I couldn't find out what the average depth was, or if it 'slid into the ocean' how much of it refreezes elsewhere or adds to the atmospheric water