Monday, October 22, 2007

I have a question

Why would global warming raise sea levels?

If my glass of ice water is full, and I let the ice melt, it doesn't over flow. This is because liquid water is more dense than ice. When water freezes it expands, so as ice melts it essentially contracts and takes up less volume. How would the melting of the polar ice caps and ice bergs raise sea levels?

I'm not a scientist, so I guess I'm missing something.

Maybe if all the polar bears drown it would raise sea levels a bit...


javajones said...

I have no scientific knowledge about this, have no idea what I'm talking about, so I'll opine. If there are significant areas of glacier atop land, and not currently affecting the level of water in the seas... If it gets warm enough to melt them, that water then runs to the sea and the oceans get fuller. It seems to me there would have to be MAJOR big glaciers melting completely to affect a sea level change. As for worrying about global warming, I'm more concerned about how the average temperature of the oceans will affect the global climate. Even a small change in water temp, maybe a degree or two, has the potential to mess up the existing weather patterns. Will the gulf stream flow backwards? Will the trade winds turn north to south instead of east to west? What will this do to international shipping? Will hurricane season last longer and affect a larger area? There are so many wonderfully worst-case scenarios to consider instead of doing the work that I need to do.
And btw, "I have a question" is the way I start so may of my conversations. Those who know me well usually look for a quick exit when I say that. :)

Alban said...

The ice cube in a glass model is based on the fact that the ice cube displaces its own volume, and so there is no change in water level as the ice melts. The model is good only when considering ice over water, which we'll call "sea ice".

The ice in the Antarctic is predominantly over land rather than water, so the ice cube in a glass model can't be utilised. If the Antarctic ice melts the sea level will definitely rise.

As for the Arctic; it used to be thought that your ice cube in a glass comparison would hold - and it does for the ice on top of water, the "sea ice". However, much of this "sea ice" also holds back galciers which are on land e.g. in northern Canada and Greenland. With the rise in global temperature, and the melting of the "sea ice" in the Arctic, glaciers are now moving more quickly into the seas; thus sea levels rise due to ice melting not only in the Antarctic but also the Arctic.

Cody said...

No, no. It's the polar bears.

jonathan said...

I say let the world get hotter...we'll grow oranges in Alaska!

Andronicus said...

Ummmm.....Ice covering land melts, flows into the ocean, raises water level.

Antartica is land covered with lots and lots of ice. When it melts, it flows into the sea and becomes ocean.

Same for Greenland, parts of Canada, Alaska, etc.