About 20,000 years ago the sea level was 100m+ below where it is today. The main factor causing this change is how much ice has built up on land. You are correct that sea ice melting does very little (if anything) to global sea level changes. However, extensive ice on land melts due to rising temperatures, where it flows into the ocean and raises sea level. That's the biggest factor in sea level rise.
Lessee if I can clear this up for you.
The majority of ice is underwater only because ice is only a little less dense than water. So, free-floating ice will be mostly underwater, with enough sticking out to make it so that a chunk of ice is only displacing its weight in water. You can test this. Take a glass of water, stick an ice cube in it, and mark the water level. Then, leave the water undisturbed while the ice melts. The water level in the glass shouldn't change (as long as you don't leave it long enough for evaporation to be a significant factor)
Global warming is not happening in all places equally. The tropics have experienced very little warming, while the Arctic has experienced more warming than anywhere else on the planet. So the planet wouldn't have to rise 90 degrees worldwide to make the Arctic and Antarctica thaw.
And the whole thing doesn't need to get to above 0C for melting to occur, in any case. Neither region is one uniform temperature year round. As parts of it get above 0C, they will thaw. And, this is a warming feedback (look up albedo), which can cause more local warming.
And, in any case, scientists are not predicting that Antarctica will totally thaw any time soon.
And, the dangerous thing about sea level rise isn't necessarily the small-sounding rise. A good part of it is things like storm surges. When sea levels are higher, storms (like Hurricane Sandy) can push the high water further inland, leading to storm-induced flooding.
First you need to start with facts to come to a reasonable conclusion. MOst of the ice caps are NOT underwater. Antarctica has the highest average altitude of any continent. Most of that is ice and most of it is above sea level. -89'C is the RECORD, not the average temperature. 50 cm is like another 1.5 feet above high tide.
"Most of the ice caps are underwater"
That is only true of the sea ice and sea ice already displaces it own weight. Sea ice will not add to the rising water level. Most of the ice caps are land based ice. Land based ice caps add to the level of the water in the oceans when they begin to migrate to the water either as glacial melt water or as the glaciers themselves move faster into the surrounding waters. Water not only expands just before it begins to freeze but also as it warmed when it is well above the freezing point. So we have additional water being added to the oceans through glacial melt waters, glacial advancement into the waters from the land and by the expansion of warming waters.
As already noted, Antarctica's glacial melt is not due to just rising air temperatures.
Please provide a link to your source on "a reliable science report that sea levels might go up by 50cm in a hundred years". Is it from here? - http://science.howstuffworks.com/environ...
I hope that you get well soon. Drink lots of fluids and get plenty of rest. Not that you would feel like running a marathon any time soon. Get well soon!
"Okay, here it goes. Most of the ice caps are underwater, ice, when it breaks off floats to the surface, now because ice is expanded it should shrink when heated up, thus lowering sea level. So why do people come up with stupid theory's about sea levels rising by 50 metres?"
You should go jump in the Arctic Sea. Your body heat will melt the ice, thus decreasing sea level, and you will not drown.
100% right the sea level will go down if the poles melt but there is also currently a cooling trend and the poles are 40% more ice covered than last year
Ice caps cover land. Then you have ice sheets that expand land coverage.
Your talking ice berg. D=M/V
And the whole thing doesn't need to get to above 0C for melting to occur,
I think someone has a prob with basic physics.
What a joke, I'm freezing.
Okay, here it goes. Most of the ice caps are underwater, ice, when it breaks off floats to the surface, now because ice is expanded it should shrink when heated up, thus lowering sea level. So why do people come up with stupid theory's about sea levels rising by 50 metres? I respect that water is most dense at 4celcius but the average sea surface temperature is 17! Additionally, because most of the ice is actually in Antarctica where the average temperature is about -80 Celsius, so why are people saying that this is going to happen when temperatures would have to rise 90 Celsius worldwide just to melt the ice caps? It's preposterous, considering it abnormal to rise half a degree in 100 years as temperature fluctuates all the time, for example in the Tudor era the temperature in Britain was on average 3 Cecius colder. I don't hate green people, I just think there isn't enough scientific evidence to say that the world sea levels will rise to 50 metres, when, in reality when that happens the oceans will be evaporating, I read on a reliable science report that sea levels might go up by 50cm in a hundred years, but surely that's just like high tide? Please put your opinions/arguments...peace out!
