Why will global warming cause the sea levels to raise?

Question

I am aware about the argument that melting North Pole ice will not contribute to raising sea levels since it’s not land based ice and the buoyancy of ice is higher than melted water. Land based South Pole ice and melting land based glaciers will contribute to rising sea levels. But what's about the rise in global temperature? Will that not increase the evaporation rate of sea water and offset the rise of sea levels through thawing land based ice sheets?

Answer 1

With regards to the water cycle, the Earth is a closed system: ice/snow, water, and water vapor are all part of the same 'pool' of water. Evaporation moves water from the oceans, but that this doesn't decrease the total amount of water = it is eventually returned to the oceans. So, warmer temperatures will mean that there may be more capacity for the atmosphere to hold water vapor, but it is unlikely that this could compensate for all the newly melted ice. So the oceans will rise.

The are also two other problems associated with global warming and melting of ice that need to be considered:

Ice or snow is white and reflects the suns heat back into space. In contrast, open water, land, and vegetation are dark and absorb most of the light and heat that land on them. So, as the poles melt and change color from white to dark, the amount of heat absorbed will increase, thereby increasing the melting rate, which increases the amount of heat absorbed, etc. ... it becomes a self sustaining cycle driving warming.

The second problem has to do with the density of water. It is densest at 4 degrees centigrade. As noted, when ice melts, the volume of water is less that the ice. But once the water gets above 4 C, it expands in volume. This means that as more and more ocean water warms to above that temperature, the oceans will actually increase in volume even if no more water is added. It sounds trivial, but the oceans are huge, and a slight change in density/volume will have a big effect.

BTW: with regards to LifeOnMars answer above, they miss the point that whether or not the polar ice caps have melted in the past, they have not melted since cities like NYC and Tokyo were built, or since islands like the Maldives were settled. Raising sea level will be quite destructive to these human environments, and also to coastal ecologies all around the globe. A little study of geography and ecology will fill in the details.

Answer 2

When the glaciers on the land melt into the ocean the level will rise. I have read that when 60% of the land ice on Greenland and Canada has melted, there will be a dramatic rise in the sea level. Surf the web with key words glacier melt and sea level rise. Check the images and you will see maps of possible results of sea level rise. If you check the web site global flooding you will see some disturbing maps for 60 meter and 100 meter rises. Hopefully this will not happen!

Answer 3

I can't give you any math, but I would presume that since scientists feel that sea level would rise, they don't feel the melting of the various ice sheets and glaciers would be offset by increased evaporation. Otherwise, you'd be right - the level of the sea wouldn't rise if there was *enough* evaporation. Since the level of the sea has been considerably higher in the past - something we can tell from the geological record - my guess is that they have reason to believe that evaporation wouldn't offset the rise from meltwater.

Answer 4

They make the assumption based on the Antarctic ice cap melting, which does presently rest on land. The only ice cap in the northern hemisphere on land is Greenland, but that will only contribut a 2-3 inch rise in ocean levels.

They have a problem with that assumption though in that the Antarctic ice cap is not melting and that temperatures in the Antarctic have not actually risen. No one really talks about that one though.

Answer 5

the north pole is ice floating in Water ,when that has melted it wont make any difference to sea water levels .

How ever antarctic ice,Greenland ,Mountain snow and Glaziers is all ice that is above the water
and this melting will certainly rise the sea warter levels

the worst part is that so much fresh or sweet or potable water is lost into the seas

here s a table of water distribution

25% of the planets surface is land
75%of the surface is water and it is rising

------------------------------...

97%of the Earths water is salt

fresh water is only 3% of all the Earths water
most of it is beyond out reach

now much ice is melting and running into the seas fresh water lost for ever.

STORAGE or Location of % of the fresh water
ice and glaziers 74%
------------------------------------
groundwater 800 meters + 13.5 %
groundwater less than 800meters 11.o%
Lakes 0.3%
soils 0.006%
Atmospheric in circulation 0.0035%
rivers 0.03%


frozen land or permafrost is not included and represent an unavailable storage of 40%

so of the 3% about 11.6 ,is easily available to us ,in rivers, lakes and ground water surface aquifers,more and more of this is becoming contaminated

Answer 6

First it's a case of what goes up must come down, so heat turns water to steam or vapor, the cold air turns it back into water and down it comes, so it's not just the melting of the ice caps that we have to worry about, it's the torrential rain that is just as deadly as we have seen In the past. But I would be more concerned with the warming of the Earth it's self. People do not or tend not to realize that we live on a ball of fire and it's only the few hundred feet of rock that stops us being fried alive. and if Global warming continues then the Molten Magma is going to heat up as well, which could mean far more volcanoes erupting and more sulphate dioxide being pumped into the air. And then of course there's the huge lumps of rock and Iron that are flying around in space as large as Mount Everest etc that could quite easily smash into the Earth which has already happened on more that one occasion. You have only got to look at the moon to see how much space rock there is flying about. So global warming sort of slips into the insignificant with all the other threats facing us every day.
Dr Knowitall.

Answer 7

Evaporated water does not vanish, it goes into in the air. The air can only hold so much water vapor. The measure of how much it can hold is relative humidity. At 100% humidity the air contains all it can hold. Any increase beyond that causes precipitation, AKA rain.

Answer 8

After the water evaporates it again rains down either on land or on the oceans. The additional water in the water cycle doesn't just disappear.

Answer 9

carbon gases trap the sunrays making the air hotter andt hat would melt the icecaps and glaciers and is in fact,and just the area around those areas (greenland ,etc)would devastate us by increasing water level and effecting sea level.

Answer 10

What is more likely is that hordes of wild eyed ninnies will imitate the lemming and leap from precipices all over the world. The submerged mass of bodies may well cause the sea to rise by more than six feet.

Tom