Let's consider this in two steps. I. Put an infinitesimal box around the ice (cube) and let the ice melt. The weight inside the box remains the same, so the box neither rises nor falls. II. Compare the density of the (now liquid) pure water inside the box to the density of the seawater outside the box. The pure water inside is less dense, so it actually has a slightly higher level than the seawater outside the box. Conclusion: If a cube of (pure water) ice melts in our full glass of _sea_ water, then the glass should indeed overflow. This seems like a pretty simple experiment. I'm about 20 miles from the Pacific, so I will try to acquire some seawater to try it out. If anyone here is near the Dead Sea or the Great Salt Lake, their experiment should show a greater effect. So any rising of the ocean is a second order effect due to the differences in salinity of ice v. seawater, rather than the (cancelled out) first order effect of the pure ice v. pure water. As an aside, I recently saw a show on Italian cooking on cable TV, and the cook used the change in density of salt water to approximate the correct salinity for a salt broth. She put a potato into the water, and added enough salt until the potato started to float. That was the correct amount for her recipe. Something tells me that this technique was probably used for thousands of years. At 05:59 AM 9/30/2005, Mike Speciner wrote:
You should note that seawater is salty, but the ice is not. So, when the ice melts, some of the salt will move from the seawater to the fresh water until equilibrium is reached. This could have some effect on the volume of water, but I don't have time to research what that might be. In any case, the seawater rise due to global warming is due to non-floating ice melting AND to the warming of the water (which increases its volume).
The NYTimes is notoriously poor in reporting on any science or technology. I would take all of it with a grain of salt.
--ms
Henry Baker wrote:
That was the point of my original posting -- the NYTimes thought that melting floating ice would raise the water level -- they were obviously wrong. At 04:09 PM 9/29/2005, dasimov@earthlink.net, math-fun wrote:
(So what's the business about floating ice raising water levels when it melts?)
--Dan