If water expands when it is frozen, how can global warming be true? Wouldn't the water levels decrease?

Yes, if the ice was all currently IN the ocean - but you have to consider that part of the mass of water is outside of the ocean (in the air / well, at least above the ocean...), and that would be added to the water that currently exists. Interesting idea, though.

Yeah, but you gotta remember that big chunks of said glaciers aren't in the water. So if they melt, said chunks won't just float. Besides, water expanding doesn't mean that there's more water, just means it expands.

Ocean levels would decrease if you were turning water to ice in a cooling trend. The opposite is happening: solid ice is melting into liquid water and adding to the oceans which in turn raises the sea level. Check out "An Inconvenient Truth" if you haven't already.

Water does expand when it melts, which would increase the water level of the oceans, not decrease it. As far as global warming.... the heat would slowly evaporate the water which would decrease the water levels. Think of it as a huge pot of water on the stove... as soon as you turn on the heat of the stove... the water starts to evaporate then goes to condensation then turns into precipitation. Eventually the water is gone.... such as would be with global warming.

If ice is floating in water, it has already taken up all thee space it will. Melting ice floating in water will NOT make the water level rise. This is 8th grade science. The supporters of global warming reason that the glaciers are not floating they rest on land. For this reason, melting glaciers would create runoff into the ocean raising water levels, blah blah. Unfortunately, the famous "hockey stick" graph has been shown to be an error of mathematics. Its unfortunate that all these "reputable" scientists base their arguments on this one single piece of evidence. But don't believe me, please check the facts yourself. Realize that potentially every scientist has an agenda, not just the anti-global warming ones.

No. The water level stays the same. Put ice cubes in a glass and fill the glass to the very top and let the cubes melt. The water will not overflow. The concern is not about the ice that is already in the water, but on land like Antarctica and the tops of mountains. That's as if you were to pour water all the way to the top of a glass and then put ice cubes in. Then the water will overflow.

I thought water expands as it gets warmer. The molecules move faster and take up more room when they heat up. As water freezes the molecules slow down and condense. Steam takes more room than water which takes more room than ice. Am I wrong? If I am than its a wonder I passed high school chemistry...

If all the ice currently floating on the oceans melted it would make no difference to sea level. .But there is a vast amount of ice on top of the land in Greenland and Antarctica. If this melted it would add to the overall sea level. Here is an experiment you can try to help you understand the concept: Try filling a glass half full of water and add some ice cubes. This represents the ice floating on the ocean, such as occurs at the north pole. Mark where the water level comes to and see if it changes as the ice melts. The level of water will stay the same. Of course when the ice melts on land and then runs into the ocean, the sea level will obviously rise as more water is added to it. Another reason warming can cause the sea level to rise is that water also expands as it is heated. It is actually at its greatest density at 4 degrees celcius. Either side of that temperature it expands. So even if there was no extra water from melting glaciers to add to the level of the ocean, the mere fact that the water was getting warmer would cause it to expand and hence the seal level would rise. In an ice age the sea level falls because a lot of the water ends up as glaciers which cover the land masses.

When the water turns to ice it not only expands outwards it expands upwards. When it melts it takes up more area in the ocean than the air or atmosphere. Just my thoughts.