We are told that global warming will raise sea levels by as much as 30' Where will all the water come from

Answer 1

Two sources:

1) Melting of ice that is not floating. The vast majority of which is on Antarctica, and a small amount is on Greenland. A tiny amount is in other glaciers. Melting floating ice will not raise water levels.

2) Thermal expansion of the oceans. As the ocean waters warm up they expand a little bit. That causes water levels to rise. It is responsible for nearly all of the ocean level rise seen in the last 100 years, which has been about 20cm or about 8".

Thermal expansion is expected to be the primary cause of ocean level rise of between 3 and 16 feet over the next 100 years. Catastrophic melting of either Antarctica or Greenland is not expected in that time frame. Antarctica appears to be relatively stable and is not expected to melt within 100 years. There is less certainty about Greenland's stability. If it's ice cap were to melt it could contribute as much as 20 feet of sea level rise. Antarctica would contribute about 240 feet of sea level rise if it were to melt, so it is the big daddy.

The interesting fact is that we could experience 15 feet of sea level rise with no melting at all. Any melting just adds to that.

Answer 2

Well, expansion of the water as it warms and melting of any land ice eg on mountain tops, the south pole etc (the north pole is sea ice so will be accounted for by the first factor - warming water).

See graphs below for sea level versus temperature rises over the past 100 years, and various forecasts.

So it goodbye New Orleans, New York, London, Washington, Sydney, Jakarta, Philadelphia...

Answer 3

Water, H²O is one chemical component that when solid, occups more space than when its liquid. So, melting Polar caps (North) will not raise the ocean level. North Pole is only ice, but Antartica (South Pole) is an continent and there, Ice isn't in the water (ok there is, but major part is over land), but above it. Melting this water, it will runs to the oceans. (Without talk about huge frozen lakes there - but this is only exceptional situations)

Another important component is permanent ica caps over montains in Himalaya, European Alpes, Terra del Fuego (Chile/Argentina), Alasca, Siberia, Andes, Carpatos, etc..... All this ice will flow down into the oceans.

With more aggressive CO² cycle, and warmer temperature, probably we will have more rains. More rains means more water than earth can absorb and all excedent goes to the oceans (When rains, earth absorb water, you can test it using cup of water and your garden.... but if you trow too much water, it will run away).

I've explained few factors, but there is much more. By the complex context, scientists only know that ocean level will rise, how much still a question. There are people talking about twice as you wrote.

Answer 4

The extra water will not come from both ice caps. The Northerly ice cap will melt (as it is doing already!) but this will have little or no effect on sea levels as the Arctic ice 'floats' on the water generating a substantial displacement equivalent to its mass. Ice currently situated on land (e.g. glaciers / Antarctic Ice Cap) will melt and flow from the land into the oceans so increasing oceanic volume.

The other important effect is 'thermal expansion' where, as average temperatures increase, ocean water will expand thus occupying more volume.

Answer 5

Some say the Polar ice caps, but that doesn't make much sense, because they are already floating in water, so their mass is already displaced. When they melt, the water level will stay the same.

A more likely source would be the Greenland glaciers, but they are not melting as quickly as the ice caps, so they are not as good of a news story as the ice caps. Funny how journalism bends reality to sell more papers and movies.

Answer 6

The warm weather will melt polar ice. The added water in the oceans will raise the sea levels.

Answer 7

Please ignore the people that are telling you that the water will come from polar ice caps. It is just the ice in the south (antartica) Ice displaces its own volume in water so the ice in the north that all floats wont have any impact on sea levels.

Yet another reason to look into this further, there is so much misinformation around that noone knows what'll happen. We will need to change how and where we live but rising tides will be of little importance compared to extremes of heat and lack of resources and energy

Answer 8

The ice caps at the north and south poles seem to be melting and the water will flow into the oceans raising sea level

Answer 9

Most of the ice in the world is landlocked. Glaciers and mountain snow. This is the water that will raise sea level when it runs into the ocean.

It is correct that melting isebergs cannot do this,
as they displace the same amount of water as they occupy.

Answer 10

The ice caps will add a very small amount of volume to the oceans total but the real problem will be thermal expansion. Most things expand as they get warmer, water also has this property. You could test it yourself with a beaker and a burner, and in small amounts the results aren't that impressive, but when you are speaking of the whole of the ocean a few degrees can, and sadly will, make a big difference.