The Removal Of Salt From The Sea

A topic that I do not recall ever reading anything about is the long-term implications of removal of salt from the sea by tectonic processes over very long periods of time.

In the posting on the meteorology blog, "Is The earth Losing Water?", I explained my idea that if coral forms in water, then the coral atolls that abound in the Pacific and Indian Oceans should not break the surface of the water. Since they do, that must mean that the earth is gradually losing water by evaporation into space. There must be water that was once in the oceans, but is not any more.

I would like to introduce a kind of parallel theory as to what happened to the water that must have been taken from the oceans so that coral atolls break the surface of the water. The scenario of evaporated water being gradually lost into space may still be the reason, or at least part of the reason, for the lowered sea level. But there is another possible reason involving the salt in the oceans.

All of the salt on earth was originally in the oceans. I explained this in "The Mystery Of Salt" on http://www.markmeekphysics.blogspot.com/ . Today, a vast amount of salt is found on land. This can only mean that salt is being removed from the sea by tectonic processes over very long periods of time.

Common rocks like limestone and sandstone are actually formed at the bottom of the sea, before being forced upward by tectonic activity. Any layered or sedimentary rock that you can see must have been formed in this way.

But when such tectonic uplifting of wide areas of land takes place, a lot of water may be separated from the oceans to form an inland sea. Unless there is enough water entering such a new inland sea by rivers and streams, the water will eventually evaporate and rejoin the oceans. But when it does, it will leave it's salt behind. We could say that this is a natural form of distillation, and is the reason that salt is found on land.

What usually happens is that the inland sea, shrinking by gradual net evaporation, has it's salt content increasingly concentrated by this shrinkage. This is why the Dead Sea in Israel has such an incredibly high salinity, it is what is left of a sea that was cut off by tectonic activity. When the inland sea finally evaporates altogether it thus leaves behind a concentration of salt, which is why there are salt mines.

In the posting "The Vital Role of Salt", on the meteorology and biology blog, we saw that the salt in the seas must have an effect on weather and climate. My reasoning is that the addition of salt increases the boiling point of water. Boiling means that vapor (vapour) is evaporating from the entire volume of the water, rather than just from the surface of the water as when water is below the boiling point. So, if salt in water raises the boiling point, and if boiling is evaporation, salt must also hinder evaporation in water below the boiling point. Salt therefore increases the heat capacity of water, and this must have an effect on weather and climate.

Now, if salt is being removed from the oceans over long periods of time by tectonic processes, this means that the seas must have had a higher concentration of salt in the distant past. That must have had a biological effect, on life in the seas, but it also must mean that 1) the water of the oceans had a higher capacity to hold heat than they do now and 2) less water would evaporate into the atmosphere than does today.

This would mean that there would have been less weather and fewer clouds, meaning that there would be less rainfall so that there would be less of the earth's water on land. It would then mean that there would be a higher level of water left in the oceans, and this could explain why coral atolls today break the surface of the water.

Two more implications of the higher salt concentration in the oceans of the far-away past is that those oceans would be warmer, since salt increases the boiling point and thus the heat capacity of water. Also, less rainfall would mean less oxygen in the water to sustain aquatic life, since the splashing of rain falling on water dissolves oxygen in the water.

Another reason that this would have made the earth somewhat warmer in those days is that the evaporation of water absorbs heat, and produces a cooling effect. This is why you have sweat glands. With evaporation hindered by a higher salt concentration in the seas, the earth would be warmer. The removal of salt from the seas could be yet another factor in cooling the earth enough to bring about the ice ages. A few degrees of cooling would bring about a cooling spiral by increasing the area covered by the ice caps, which reflect away solar radiation.

Clouds would seem to be a vital factor in determining the temperature on earth. However, clouds work both ways. The earth absorbs solar radiation by day, but then re-radiates it back to space by night. Clouds tend to block both solar radiation and re-radiation.

Cloud cover during the day produces a cooling effect by reflecting solar radiation back to space, but cloud cover at night has a warming effect by acting as a blanket and preventing re-radiation by the earth back to space. Since cloud cover tends to average out as about equal during day and night, the two cancel each other so that clouds have little overall effect on the earth's temperature.