Global warming as compared to ice cubes?
* The relationship between glacial ice and sea level is analagous to a drinking glass filled with ice cubes and water.
* As the ice cubes melt, they change from solid to liquid water; but because the total amount of water in the glass does not increase, it does not overflow.
* Glacial ice melting merely represents a change of state; no "new" water is being created, so there should be no rise in the mean sea level.
But aren't glaciers on land? They are not really like ice cubes are they? If they were why would it do anything since water is larger in the form of ice anyway?
Answer:
Hi there,
yes and no... have you ever seen pictures of the huge masses of ice arount the North Pole? They are really mountains, not ice cubes. Now if we apply the comparison to a glass of water with ice cubes in it: it would be a glass already full with water and on top of it, only half way in the water, there would be huge ice cubes, piled on top of each other, maybe also supported by a drinking straw (since some of the ice on our planet is also on land, as you correctly observed). If we left our imaginary drink too long in the sun, the icecubes would melt, and our glass would overflow.
But the rise in sea levels will not just be caused by the melting of polar ice. It will also be caused by the melting of our glaciers on land, water which fills our rivers or pours into our "ground water" and eventually ends up in the ocean.
Actually, I am not that much afraid of the rise in sea levels, but far more in the effect a huge chunk of melting ice can have on the undercurrent system in our oceans, e.g. the gulf stream. This can really affect our climate much stronger than the mere flooding of some coastal areas or even entire countries if they happen to be unfortunately flat...
No matter what kind of attitude we have towards the question of whether global warming is a fact or the hoax of the century: it sure doesn't hurt to reduce CO2 and to save energy wherever we can. It also doesn't hurt to invest in cleaner energy. That can create jobs and independence from countries which threaten to cut their gas or oil supplies to our industries at any given moment. There are so many reasons to be reasonable, it astonishes me that people still discuss the validity of the global warming argument or thesis.
Does it really matter who is right? Or does it matter how we want to shape our future on this planet?
Good luck and all the best
Anna
Global warming is a theory and the rise of the ocean's water is also theory.
Free Tibet.
The rise is sea level will be almost entirely due to the melting of land based ice fields. This water will flow into the oceans and raise the overall level of water. There will also be a very small increase in sea levels due to expansion as the average temperature of the ocean increases. The melting of the Arctic ice fields and other ice that is currently floating on the ocean will have no effect on sea levels. This mass of water is already entirely supported by the ocean. Thus, the current sea levels account for the volume of this material. When it melts, the level will not change. You can simulate this quite well by filling a glass almost full of water, then adding sufficient ice to bring the level of LIQUID water to some specific level (for example say 1/4 inch from the top of the glass). Note that the top of the ice is above the liquid level, this is because ice is less dense than water and floats. Note also that as you added the ice, the level in the glass increased. This is because the weight of the ice was supported by displacing water until the volume of water displaced had exactly the same mass as the ice.
Now let the ice melt. What happens? The liquid water level remains constant.
Sea ice causes no increase in sea level when it melts.
Glaciers do, however, cause an increase in sea level, and in fact the level of the oceans has risen 120 meters since the last ice age. Melting the Antarctic ice cap will cause another rise of this magnitude.
It's the third choice that is flawed - yes, it is a change of state and not a creation of water, but the last time Antarctica was clear of ice was before man arrived on the scene. There have been times where a good portion of the North American continent was below water - that's how we got our oil to begin with. So, yeah, relative to WAY back then, there will not be a sea rise.
Relative to now, on the other hand, there will be a LARGE increase of sea level if Antarctic glaciers melt. But not to worry unnecessarily, this is estimated to take over a thousand years at the current increasing rate.
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