Archimedes’ Principle and Sea-Level Rise
This article motivated by a question from the audience during my presentation about climate change and global goals. He told me, it is impossible while the melting iceberg from north and south poles could sink the land. He used the Archimedes notion. Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.
If we place water and an ice cube in a cup so that the cup is full to the brim, what happens to the level of the water as the ice melts? Does it rise (overflow the cup), stay the same, or lower? Based on the fact, the answer is nothing happen. The water level still the same. This is a little bit confusing.
This experiment is not falsified, but it misleads in its conclusions about the impact of climate change on the sea level. The experiment illustrates the Archimedes’ Principle. But this study from the University of Leeds says, “Because seawater is warmer and saltier than floating ice, changes in the amount of this ice are affecting global sea levels.” The experiment also fails to take into account the water level before the cup was filled with ice. Ted Scambos, the senior research scientist at the Cooperative Institute for Research in Environmental Sciences, explained: “If you did the same experiment with a cup of water that was almost full and then you added a big iceberg to it, it would squash over the top.”
The problem is the experiment and the real condition different. We can’t analyze the arctic iceberg like floating ice in a cup of water. Roelof Rietbroek, Geodetic Earth Scientist from German, states that Archimedes’ principle is formulated in terms of forces that are linked to weight (or equivalent mass) and not to volume. Furthermore, melting sea-ice may cause small changes in sea level. The salt concentration in icebergs and sea-ice is less that of the seawater which holds it buoyant. So if sea-ice melts in the water, the local salt concentration, and hence the seawater density, decreases.
To maintain a constant pressure at the bottom of the ocean, which is a fine assumption when considering the surrounding waters to be unchanged, one would (regionally) need a higher column of less dense water. The Archimedes argument breaks down there because of the density of the water does not remain constant throughout the melting process. Density changes also occur when the temperature of the seawater changes due to the latent heat needed to convert ice to water, essentially counteracting some of the above effects. So, the melting of icebergs a sea-ice could cause some sea-level change. However, this effect is expected to be smaller than the direct contribution of the grounded ice sources.
There are a lot more icebergs being created because of ice flowing off of ice sheets, like Greenland or Antarctica. Because when you take ice from the land where there is a significant part of the mass that is above sea level and put that ice into the ocean, that raises the sea level. Besides the total amount of the non-floating Arctic and Antarctic ice is about 50 times higher (which is 660.000 cubic kilometers are floating), and because this is not currently floating (and displacing water), if it were all to melt the sea levels would rise significantly.
As a physic student, I argue equivalent mass could change the fact. The melting iceberg increase sea-level rise for a bit. But, how about a warmer condition? Of course, the volume bigger caused by expansion. It is more complicated when we also count the salinity factor. Yet, the biggest challenge comes from the effect of global warming itself. The warmest our earth, the more catastrophe happens.
Case closed.
