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

Question

If water expands when it is frozen, wouldn't the melting of the glaciers cause the overall water level of the oceans to decrease? Your thoughts/theories on global warming, please...

Answer 1

Lots of good answers already. Water is a very unusual substance. "uselessadvice" has is right about water has it's greatest density @ 4 degrees C. A body of water can be stratified into layers. As you think of a lake, the coldest water is at the bottom. As the water gets colder and colder it gets more dense. Then it becomes a solid and crystallizes. The structure of the ice crystal become less dense and floats. The crystalline structure actually pushes the water molecules away from each other and thus expands. This is very unusual because water is one of the only (if not the only) substance that floats as a solid when it is within its on liquid (if that make any sense). So maybe that will help " Jennifer T" a little.

Now everyone else has pretty much the right idea. Its not the ice that is in the water that may be the problem its is the ice upon the land that could be the problem. But everyone is forgetting one thing: the water cycle. If the climate is warmer then not only will the ice melt, but more water will evaporate also. This could cause more water to be held in the atmosphere. The earth is very resilient and the clouds that would form will actually cool things back down, unless it is taken to an extreme. In an extreme situation the planet would become like Venus and have a warm and very soupy atmosphere.

But for the most part, earth has gone through many cycles of warming and cooling though millions of years. We have very little impact on the earth. We may think that we can do something about it; but we are pretty miniscule when it comes right down to it. We have very little power over the earth and the cycles it goes though.

Answer 2

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.

Answer 3

Water expands yes but the water level remains EXACTLY the same for sea ice. If you lock up water on land with expanding glaciers then the sea level could drop. During the last Ice Age water levels were more than 100' lower than they are today. If the existing land based glaciers were to melt then sea levels would rise because you are taking land based water and putting it in the ocean.

Answer 4

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.

Answer 5

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.

Answer 6

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.

Answer 7

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.

Answer 8

Lets' address the premise. The population of the Earth keeps expanding, and projects in China demonstrate the need for fresh water supplies. As the ice caps melt, the largest reserves of fresh water in the world are depleted.

Answer 9

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.

Answer 10

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.