Naked Science Forum
Life Sciences => The Environment => Topic started by: guest39538 on 22/09/2017 14:18:57
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In a conversation with a friend, I feel my friend just came out with some interesting thinking.
Now to explain I am going to use a glass of water, we are going to fill the glass to just under the top of the glass. I am now going to add some ice cubes that by the density of the ice cubes the water will rise to the top of the glass , not over flowing. Now when the ice melts the water level will stay the same because the mass remains the same of the combined water and ice when the ice as melted.
So in reality the ice density in the sea makes the sea rise like the water in the glass. If we removed the ice the sea would drop in levels, if the ice melts the water level will stay the same because the mass remains the same.
What do you think?
(Sea level is only the sea level because the ice is making it rise to that level).
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Your friend is correct for fresh water ice floating in freshwater, but that isn't the case for ice on the earth.
Ice at the North Pole is floating, but that is freshwater ice (mostly + dust etc) floating in seawater. If you do the sums you will find that for freshwater ice in a saltwater tank, when it melts the water level would rise slightly. The other thing to consider is that a lot of the earth's ice is not floating eg, Greenland, Antarctica, Canada, Siberia so that would directly contribute to a sea level rise.
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Your friend is correct for fresh water ice floating in freshwater, but that isn't the case for ice on the earth.
Ice at the North Pole is floating, but that is freshwater ice (mostly + dust etc) floating in seawater. If you do the sums you will find that for freshwater ice in a saltwater tank, when it melts the water level would rise slightly. The other thing to consider is that a lot of the earth's ice is not floating eg, Greenland, Antarctica, Canada, Siberia so that would directly contribute to a sea level rise.
Ok, thank you , I can ''see'' the mechanics involved in that and agree with your reply, because if we added more ice cubes to the already full glass the water would rise and overflow.
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I'm going to move this to environment section, because it is an interesting question
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There is also the consideration of gravity: https://www.thenakedscientists.com/articles/science-news/gravity-may-make-sea-level-rise-worse
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Sea level rise is partly due to melting of land ice into the sea, but luckily that is happening relatively slowly (if all of the ice melted, the seas would go up many meters!) The other major component is thermal expansion of the water (same principle as a liquid thermometer--as the water warms up, it swells slightly, becoming less dense, and taking up more space.)
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That's a very good point @chiralSPO
In an interview I did a few years back about sea levels and climate change, the interviewee pointed out that the seas are still smaller than they should be owing to the eruption of Krakatoa over a century ago.
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Another thing to consider is the earth was almost completely covered in water up to about 2.5 billion years ago. So the question becomes, where did all that extra water go? One answer is the movement of the crustal plates, can take water below the surface and crust, where plate boundaries submerge. The result was land started to appear as water was taken below the crust.
The water economy of the earth is not just on the surface. It is within the crust. Also, large deposits of water have been found below the crust in the upper mantle. One such mantle water deposit, near SE Asia, is the size of the Arctic Ocean. There is also a trench in the Atlantic ocean where the crust is eroded away and the mantle is exposed. This suggests sub mantle water, gushing into the oceans, is an active part of the earth's surface water economy.
It is very possible that the estimates for sea level rise, due to global warming, are accurate, if we work under the assumption of a closed ocean water system. But if we assume a mantle-crust-ocean water system these estimates are not that good. They are way too high.
Water is very unique. At the temperatures and pressures of the mantle, water becomes a superionic phase, with tremendous solvent properties, for any viscoelastic mineral phase in the mantle. With such solvant power, water can theoretically diffuse toward the core of the earth driven by solvent based entropy; 2nd law. There is no restriction of movement.
The water economy, theoretically, goes beyond the surface and mantle, all the way to the core, where water once again changes phases, first to become ionic water, at the outer fluid core, and then metallic water at the solid core, where the water can amalgamate with the solid iron. This is solid water but more exotic than ice, with tremendous electrical conduction properties.
My theory is, Mars once was covered by substantial water. However, its water has been commandeered to below the surface, The huge amount of Martian metallic water has overwhelmed Mars's iron core and neutralized its magnetic field. The phase boundary between the ionic and metallic water phases will rust the surface of the iron core, extracting free energy. The result is an active displacement of minerals, making Mars seismically active.
The electron flow from the rusting iron of the core, to the surface water of the earth makes the oceans slightly negative and even forms the electrons for lightning. This is driven by the positive charge created by solar evaporation of surface water into the atmosphere. Oceans levels are very complicated.
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There are some other considerations, for the levels of the oceans. The earth bulges at the equator. In terms of the oceans, this means the water at the equator, is in a sense, at the top of the earth's ocean hill. The oceans are higher at the equator in terms of distance from the center of gravity. However, the water of the earth does not all flow toward the poles; seeking its own level. However, some of the water does gain elevation at the poles, as expanded ice.
Studies have also shown that the earth is denser N-S than it is E-W. The earth is wider at the equator, but it is also less dense. The earth is smaller between the poles, but it is denser. It appears gravity is a wash so ocean currents are driven by thermals, and not elevation from center of gravity.
There is also another observation that core of the earth rotates faster than the surface. The surface of the earth is being dragged along by the core, not the other way around. It takes hundreds of years for the core to lap the surface. This faster core rotation requires an engine. This is provided for at the ionic-metallic water phase boundary and the corrosion of the iron core by exotic phase water. The core always moves in the same direction, but the magnetic field can periodically reverse polarity.
The equator is the zone of highest solar heating. This evaporates the most water and therefore generates the highest levels of positive charge within the atmosphere. This and the lower density of the E-W; equator, suggests the solar heating at the equator helps to drive maximum water migration toward the core; lowered density. The equatorial currents, between the core and surface; right hand rule, define the magnetic field direction.
In this model, the seasonal tilting of earth's axis is driven by the core, based on maximizing the corrosion of the iron; fe energy release. The seasonal tilt is a way to maximize surface area for water-core contact and the release of free energy within the core in response to the sun.
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