I posting this here because there a good analytical minds here.
An experiment: Fill a tall clear glass half-way with ice cubes. Then add enough water so the bottom cubes no longer touch the bottom (i.e., they are all floating). Now put a mark at the water level and wait until the cubes all melt. Did the water rise above your mark?
In my case, it didn't.
R1
Here is an alternate, and probably more appropriate, test that you could try.
Start with a rectangular fish tank. Place dirt and rocks in it such that the dirt and rocks are high up on one end and have the dirt and rocks slope down toward the other end to where they are at zero height on the other end.
Then, fill it half way with water and place ice in the water and also on the dirt/rock "hillside" that is above the water line. That would more accurately replicate the way that glaciers are on earth -- meaning that the glaciers are both on top of the ground/dirt/rocks and also partially in the ocean where the ocean meets the ground/dirt/rocks.
Wait until the ice in the fish tank melts. Let us know if the water level rises in the fish tank as the ice melts.
Wanna take a guess as to what will happen to the water level?
Rebel,
You're focusing on the North Pole where everything is floating in the ocean. Think about the South Pole where much of the snow and ice is on land and will run into the oceans as it melts.And of course there's lots of snow and ice on North America, South America, Europe, and Asia. As you can see I don't think much of your ice cube experiment.
Dave M.
Yes, and depending on who the co-pilot is, and what his mental state at the time is, you might get a really close-up view of the icebergs and glaciers; at least for a few seconds before the crash.
What? Too soon?
When the ice began to float, the contents reached equilibrium. The small amount of ice above water line would suggest that the level would rise as it melted. Not so. The ice crystal structure is larger than the liquid therefore it will float because the weight per volume is less. As the ice melts it goes back to the liquid structure which is smaller. Therefore, the water line you marked won't change. Make sense? phil k.
Per Rebel1:
I'm no geologist but AFIK, the glaciers are not floating in the ocean. I think that's what icebergs are. Glaciers are sitting on land, so that when they melt their water is added to the ocean. ref:
Sounds to me like the math/physics are pretty straightforward assuming that the volume of the oceans and the volume of the glaciers are known but the wild card seems to be how fast the glaciers are melting. viz:
Rebel1 wrote in news:dHiTw.148476$ snipped-for-privacy@fx17.iad:
That's not really relevant, because it models only sea ice. You need to consider everything:
-- Most of the Arctic ice cap is sea ice, floating on the surface of the ocean. Melting this ice won't change sea level significantly, because it's displacing an equal mass of ocean water. (There will be a slight increase because fresh water is less dense than salt water.)
-- Most of the Antarctic ice cap, and part of the Arctic ice cap (Greenland) is on land. Melting this will cause sea level to rise, because it isn't displacing any ocean water now, and most of it will wind up in the ocean. (Not all of it, because there's a substantial basin in the Antarctic interior that will become a large freshwater lake if enough of the southern ice melts.)
-- Part of the Antarctic ice cap is resting on the continental shelf, *below* the surface of the ocean. Melting this will cause sea level to *drop* because it's displacing an equal *volume* of ocean water, not an equal mass.
So what happens to sea level if the polar ice caps begin to melt depends heavily on how much of which ice cap liquifies.
Good point.
R1
Excellent points.
R1
Interesting. So asking questions, wondering about things, trying experiments and seeing what others have to say about it is "Good right wing thinking"
What is good left wing thinking then?
Rebel1 wrote: ...
here's a few more:
as the mass of the water held in ice at the south pole decreases we get two additional effects, one is that the overall ocean level increases for the northern hemisphere increases not only from the amount of new water added to the oceans but the rebound from the water currently attracted to the gravity effect from that much mass. the other effect is that as the cold water warms up we also get an added boost in volume.
one thing i don't see anyone mention very often is the amount of water that is being pumped from the ground, used in sewage/water supply systems and then dumped into the oceans. if we can reverse the trend and impound more of this water in reservoirs and ground water that can help slow down the rate of ocean level increases.
where there are huge areas of inland seas below sea level we could pipe sea water into them to help moderate temperatures and evaporate more water into the air to increase rainfalls/snowpacks downwind. this would mean some plans for harvesting the salt from such seas to keep them from getting too salty, but last i knew there is a good market for sea salt... we do really need a good plan to address the Salton Sea mess anyways...
as it goes, where one of my relatives is at he's lost
1ft of sea level and has only another foot and a half before that is gone. another 20-30 years and it is likely where he is at will be close to under water.songbird
What kind of toast do you put in your toaster?
Good catch, Mr. Cresswell.
- . Christopher A. Young learn more about Jesus .
Is that left wing thinking?
- . Christopher A. Young learn more about Jesus .
Groupthink. Collective wisdom, as dictated by the left party leaders. No room for facts or independant thinking.
- . Christopher A. Young learn more about Jesus .
Yeah, the comment is a bit out of line isn't it. We can only speculate why Rebel1 thought he knew better than all the worlds scientists.
But then, Rebel1 claimed "there are good analytical minds here". (Yes, I laughed so hard, I almost choked.)
Maybe it's not so out of line to guess he was referencing those mass poster nut jobs that live in my kill file.
The idea that scientists are scammers making things up for profit does seem to come from one political party.
But only Rebel1 can explain why he suddenly thought he was smarter than a bunch of people that actually studied the subject.
I wonder if he actually performed his "tall glass" experiment. I bet it was a tall jelly glass and a sharpie. We all know calibrated beakers, are for pinko scientists.
But we don't live in a glass of iced water do we, and also hotter water also takes up more room. Its not just the ice. I'm probably wasting my time replying to this, but it is an interesting subject, nonetheless. The current situation is that the ice is also stuck in a place and when it melts is is free to flow to other places, and as although ice takes up more room than water due to its crystalline form, the fact that much of it is not actually in the sea has to be borne in mind here. A glassier is a frozen river flowing to the sea after all, and if it thaws that water will get to the sea faster.
Of course evaporation has a part to play in the opposite direction, but as sea levels are rising, I think the trend has to be for this to continue to places in the world where land is low lying. End of waffle. Brian
Essentially you are correct. Assuming nothing happens, like a nuclear war, that makes a fundamental change in the population and the atmosphere, the earth will get warmer. The science is certainly looking that way right now. If we are going to blame CO2 levels, it needs to be pointed out that when you track CO2 for the last 10,000 years, it tracks world population as closely as any other metric, That can easily be explained by agriculture. They cut down forests and plow up grasslands to grow crops. The plants they grow are harvested as soon as they are mature so they are not much of a CO2 sink.
Any global warming plan that is not going to scrub a few billion off the population is simply snake oil sold by hucksters like Al Gore who wants to make billions from a carbon tax by selling worthless "credits" for that money.
[snip]
Most of these folks see some headline written by a clueless reporter (often from both sides of the debate) and elaborate on that, rather than actually digging into the science itself.
There are several contributors to planetary mean sea level (MSL).
- Meltwater from land-based glacial ice - Fossil water runoff - Isostatic rebound - Wind
The first, meltwater from land-based glacial ice encompasses the high altitude glaciers (e.g. in the himalayas, upper Rockies, Peru, mt. Shasta, etc), the greenland icecap and the antarctic icecap.
The second, fossil water runoff is from pumping geologic water from underground for irrigation and other human uses. This adds water to the hydrologic cycle which raises sea level (in fact, this alone is responsible for something like 40% of the sea level rise in the 20th century).
The third, isostatic rebound, appears to lower sea level at certain measuring stations as the land continues to recover from the weight of a mile of ice 10kya. A counterpoint of this is areas like southern La., where the land is sinking due to silting at the mouth of the mighty muddy.
The largest two regions of land-based ice are the greenland icecap and the antarctica icecap. In both cases, the amount of time required to melt 100% of the ice is measured in thousands of years (note that the air temperature in antarctica is below freezing for 10 months of the year). Since the land ice in antarctica is surrounded by sea ice (which can melt more rapidly as the temperature of the water it is floating on changes with time, natural cycles and other forcings), a concern is that if all the sea ice melts, it will open the way for the land-based glaciers to flow more rapidly towards the sea and calve bergs, which will inevitably cause higher sea levels.
As for Wind, certain coastal areas measure higher sea levels than others due to the wind pushing water towards the coast (leaving aside any tidal effects).
All this makes it difficult to measure MSL accurately using surface based measurements. Modern measurements use satellite altimetry, which generally requires some amount of correction due to orbital decay characteristics and instrumental differences beween generations of measurement satellites.
Current global sea ice area:
Current global sea ice anomoly (i.e. difference from average since 1979)
Global, Arctic and Antarctic ice area:
Note that the planet currently has _more_ sea ice than the average since 1979 (when satellite measurements began). Note also two years ago, when there was 2 million km2 less.
As others have pointed out, the melting of the sea ice has effectively no effect on MSL; however it does alter the albedo of the pole(s) which may reduce the amount of insolation reflected back to space, leading to additional warming of the surface water.
Icebergs are not glaciers -- they are pieces of glaciers which fell off. When they melt they will not raise the level of the ocean but when they fell into the ocean in the first place they _did_ raise the level. If you don't believe that, fill your hypothetical glass to the brim and then, very gently, place an ice cube into it and see what happens.
Unless you've actually been there you would not believe the amount of ice covering the land in Greenland. When it melts, whether in the form of icebergs or not, you better believe that the level of the ocean will rise. And Greenland has a fraction of the amount of ice that Antarctica does.
Per Stormin Mormon:
Mainly bagels from the day-old shelf...
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