If all the ice in the polar regions melted immediately, you would get a massive rush of fresh water into the ocean from Greenland and Antarctica that could cause tsunami's throughout the world - especially in the North Atlantic and the Southern Hemisphere. This is pure speculation on my part - but I hope it is common sense. I do not think that will ever happen - as nothing could cause ALL that melt to happen so fast with a resulting immediate dump into the ocean (and I've considered meteors and bombs - global warming would never cause that fast of a melt).
If it all melted over a period of years or even centuries, there would be two immediate results: an increase in sea level and a massive change in deep ocean circulation resulting in massive climate changes.
SEA LEVEL RISE
The sea level rise, according to Climate Change 2001 (1), from the Greenland Ice Sheet would result in 7.2 meters and for the Antarctic Ice sheet it would be 61.1 meters - for a grand total of 68.3 meters or 224 feet of ocean level rise. These numbers account for expected isostatic rebound and ice below sea level - so they are lower than the volume of water contained in that ice would otherwise dictate. However, the measurement techniques and feedback mechanisms are in constant refinement - both up and down. From my search, I could find nothing that updated those depths more accurately, and the refinement techniques I read up on make only very small changes - so these are probably the best estimates we have.
These sea level increase amounts do NOT account for the amount of sea level rise from the expansion of water in a warmer world. That is currently expected to cause about half of the sea-level rise (3). Note that no estimates of sea level rise typically made include the total sea-level rise from the melt of the Antarctica ice cap, as that does not seem in the realm of possibility in the next millennium.
This number also does not include the melt of sea ice - which would not contribute significantly to sea-level rise, as the ice is already floating and taking up most of the volume it would as melted water. There would be an increase of about 4 cm from all the sea ice melting due to the fact that ice is lower in density and therefore part of the ice floats above the sea water surface. However, compared to the 224 feet, or even to the 50 to 150 cm currently predicted by 2100 that amount is small (Vellinga et al., 2008).
OCEAN CIRCULATION CHANGES
The exact results of that circulation change is highly speculative, but similar events occurred after the last ice-age and are called Heinrich Events (1). They actually resulted in a shutdown of the North Atlantic Deep Water circulation which resulted in cooling periods lasting centuries. The little ice age that occurred in years from ~1400 to 1850 may have been due to something similar. So we could end up in a temporary cooling period as a result. Heinrich type events would likely happen even if they melted over a matter of decades (meaning we did not have the tsunami's referenced above). So any global climate change is likely to have fits and starts. Current science suggests that the warming we are currently experience is highly moderated by ocean circulation (1).
Regarding the timing of that melting, a fast melting is predicted to melt the Greenland Ice Sheet in 2000 years. At this point, even with the most dire of global warming scenarios, nobody seriously expects the Antarctic ice cap to melt completely. There are concerning new findings about the rate of melting, but the Antarctic ice sheet is only calculated to contribute about 10% of the current sea level rise in the next 100 years (4).
Finally, I want to end by saying that the level of understanding demonstrated by some of the other answers is concerning. Make sure to get your information from reliable sources that source peer-reviewed science. The idea that global warming is not happening is popular among certain politically driven individuals, and unfortunately, the public perception is that the science is still in question(59% of American’s believe there is significant disagreement (5)) . It's not. While the science will never be "final": there will always be more to learn and understand, the fact is over 97% of scientists who published about climate change in peer-reviewed journals since 1991 and take a position on the science of global warming endorse the fact that humans are causing global warming (6). Every argument I have seen against it in the last few years has had either NO support from the evidence or overwhelming counter evidence and far better explanations (7). Skepticalscience.com is a great site for laypeople interested in the current information and explanations regarding global warming (7).
If the Greenland Ice Sheet melted, scientists estimate that sea level would rise about 6 meters (20 feet). If the Antarctic Ice Sheet melted, sea level would rise by about 60 meters (200 feet). [1]
"I guess then we would at long last find the Northwest Passage" That has already been found and last year some people in a fiberglass boat named "belzebub II" made it through. [2]
It has happened before. our Earth is 4.5billion yrs old and continents move around very slowly.
As long as Antarctica is over the south pole it is unlikely that polar ice would melt, but everything changes maybe in a billion years time the continents will have moved and new mountain ranges formed, new lands formed, we might have no ice at the poles then. but we will all be long gone by then.
Massive flooding -- but it's not happening because the ice is NOT melting.
Both of the polar regions are currently normal or above normal in ice.
NORSEX Graph - The Arctic is currently in the statically normal range - Look at the RED line for the CURRENT values, 2013 - http://arctic-roos.org/observations/sate...
Antarctic Sea Ice, Sea ice extent well above normal in May, according to NSIDC figures (June 6, 2013)
http://notalotofpeopleknowthat.wordpress...
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According to the IPCC TAR, that would be:
Antarctic = 61.1 meters sea level rise
Greenland = 7.2 meters sea level rise http://www.grida.no/publications/other/i...
Land ice = 68.3 meters sea level rise
Sea Ice makes no difference, since it is already floating in the ocean. Thus, its melting would not affect sea level at all.
Here is an interactive map that tells you what the world would look like if sea level rose 60 meters. http://flood.firetree.net/?ll=53.8058,-2...
However, don't hold your breath waiting for this to happen in your lifetime. http://upload.wikimedia.org/wikipedia/co...
The warming has been happening in the Arctic, not the Antarctic where most of the ice is. [3]
Satellites have been monitoring sea level since 1993, and the upward trend in sea level is only a boring 1 foot per century. http://ibis.grdl.noaa.gov/SAT/SeaLevelRi...
Sea level is just now getting back to the level it was at a millennium ago. http://www.salt.org.il/sealevel.html
There would be other effects:
- The "United Nations Environment Programme predicted that climate change would create 50 million climate refugees by 2010." -- http://wattsupwiththat.com/2011/04/15/th...
These refugees never happened, but if your sudden scenario magically happened, they would exist.
- As the sea ice melts, http://www.woodfortrees.org/plot/nsidc-s...
ocean traffic would increase over the Arctic Ocean. http://www.bloomberg.com/news/2013-05-13...
- People would start farming where the glaciers used to be.
It will never happen like that but sea levels will rise. This would be @ 200 feet if all the glacial ice and Greenland ice shelf and Permafrost melted too.
Nothing, because this is a moot question: WILL NEVER HAPPEN. Incidentally, the ice in central Antarctica is now thicker than it was twenty years ago.
If it happened in one second first a fog then clouds storms and snowstorms .
The sea will rise, unbalancing our atmosphere as we know it, flooding many cities, towns, villages, etc that are below sea level.
GOD WILL SAVE US!!!! BLESSED IS HE!!!!
nah we would be ******
We all die.
