Ok, this has been buggin’ me (what does this say about me?):
Part of the concern about global warming is that it will “melt the polar ice caps”, causing ocean levels to rise, and jumping up home prices in the newly formed Arizona and Nevada beachfront areas.
Now, my understanding of the mechanism for this is that, as the temperature increases, the latitude at which water is perpetually frozen increases (gets closer to whichever pole).
Why, if we’re not talking about 10-gazillion year old glaciers sitting on a land mass, would this cause ocean levels to rise? If we’re primarily talking about floating ice and “land masses” consisting of frozen sea water, the water resulting from the melting ice will take up exactly the volume of the submerged portion of the ice (approximately 90% the volume of the solid ice). I don’t see how this would cause ocean levels to rise any more than melting ice cubes would cause your soda to overflow your glass.
Are my premises here wrong? How would this work??
Regards,
JonTheGeekWithTooMuchTimeToThinkAboutStupidStuff
Antarctica is a continent, you know. Most of ice on Earth is on land (the Antarctic cap is a whole lot thicker than the Arctic cap), so melting it would indeed add to sea levels.
You are forgetting Antarctic ice (most of it sits on top of the depressed continent), and holds 91.49 percent of total world ice.
According to this USGS Fact Sheet …
If all the ice melted outside of Greenland and Antarctica, sea levels would expect to rise by 0.45m (less than 18 inches).
If just the Greenland ice melted, sea levels would expect to rise by 6.55m (around 20 feet plus).
However, if just the Antarctica ice melted, sea levels would expect to rise by 73.44m (around 240 feet plus!).
I guess that’s a big part of my question: is it reasonable to predict the melting of ice that has existed for, what, hundreds of millions of years? billions? tens of billions? on the Antarctic and Greenland land masses?
Am I correct that the issue is at what latitude permanent freezing occurs? How much global warming would need to take place to increase the temperatures of Northern Greenland and inland Antarctica enough to cause melting?
And, where is this “Eastern Antarctica” place listed on the USGS site? I would’ve thought that, as you moved away from the pole, all you could have was “North Antarctica”.
I’m really not trying to start an argument here. I’m just trying to get clear in my mind what is going on, and what could happen.
Not to change the topic, but the Antarctic ice hasnt been there for “tens of billions” or even “billions” of years.
During the Jurassic period Antarctica was much further north, and that was only 150 million years ago.
The Earth itself is, I believe, 4.5 billion years old.
Another question, though, is how melting ice would effect the amount of oxygen in the atmosphere.
My understanding, based on reading etc. (this is out of my area so I’m far from an expert) is that the climate, rate of melting etc. are quite sensitive to the circulation of ocean currents and the currents are sensitive to warming which melts ice (fresh water) resulting in dilution of the salt content of the surrounding sea which affects ocean currents.
So there is the distinct posibility of positive-reinforcement mechanism of climate change which melts ice which alters ocean currents which results in more climate change. The whole process is only now begininning to be looked into.