Yes, we should take global warming seriously, but no, melting of the ice in the Arctic will not lead to rising sea levels. It is floating ffs ...
Physics lesson:
1. Archimedes' law: Any body floating in water will push away an amount of water equal to its own weight. This means that any solid body with an average density lower than that of water, will float. This is why a human can swim as long as he/she has air in the lungs - but if the lungs are filled with water, you sink.
2. As you all know, ice is the solid form of water. Unlike many other materials, water expands when it freezes (the highest density is achieved at 277, water freezes at 273). This means one ton of ice takes up more space than one ton of liquid water (if I'm correct, about 10% more). Thus ice will float. This is the reason why a lake can be frozen on the top and liquid on the bottom.* This leads to the following (as we all know); An iceberg is floating with only 10% of its total volume located above the surface.
3. What if the iceberg melts? Yes, its density will increase because it turns into liquid water. When it is completely melted, it will have the same temperature (and thus the same density) as the surface water surrounding it. The volume will of course decrease because the
mass is the same as before. Thus, no increase of sea level.
So, the only risk is if glaciers located
on land melt. Then we would have a net increase of the amount of water in the ocean. With global warming, this might or might not happen. One thing that works
against glacier meltdown is increased precipitation; a milder climate in the arctic region will most likely increase the amount of precipitation. If the precipitation comes in the form of snow (which it does for much of the year) this will lead to the glaciers growing, not decaying.
[/physics lesson]
[rant]
And by the way, forget the pictures from Al Gore of ice plunging into the sea. This (a process called calving) would happen anyway, even with a
cooling climate, because glaciers are moving all the time. This is forced by gravity. A glacier typically grows on the middle and "gives away" ice closer to the sea/fjord/river.
For the polar bears; yes, hunting becomes more difficult for them, but I think that the problem might turn on us humans. The polar bears could move in to the mainland of northern Canada, Alaska, Russia, Norway and Greenland and become a threat for other species along the coast. I think these animals are adaptable enough to make a living also without the ice - after all, they are closely related to other northern bear species like the grizzly, and if they are forced to change their ways of hunting they might very well be capable of that. By that I don't mean we should stop caring and think everything will be OK. I just mean that we shouldn't drown the serious research in campaigns with cute polar bear puppies on a shrinking iceberg, or glaciers calving ice into the sea.
[/rant]
Forostar said:
That's why we need more seals!
*runs*
That, and because their coat makes for nice vests and shoes
*) Obviously the freezing starts where the water is in contact with the cold air, that is, at the surface - and if the ice had sunk, it would melt in contact with the warmer water. Then it would take much more time to get a layer of ice anywhere in the lake because all the water in the lake would have to be at the freezing point before we could get any stable ice. But since ice floats. only the upper few meters (or even centimeters) can be close to the freezing point and we could still have a lake covered with ice.
, it's been neglected for some time