It is mentioned in Quran that everything in the universe has a purpose. So, why does Allah cover over 70% of the Earth with sea water that human beings can't consume unlike the fresh water that is helpful for humans?
What is the hidden wisdom behind this? Is there anything related to this mentioned in Quran or Hadith?
A logical or a scientific explanation would really help, thanks!
Humans are not the only creatures on this Planet,
Scientists have described well over 1.7 million of the world's species of animals, plants, insects and algae. (Number of Species Identified on Earth)
Out of those, just imagine how many might be aquatic? That salt(ocean) water out there stands enough for the purpose to those marine inhabitants.
If you stop your question at...
why does Allah cover over 70% of the Earth with sea water?
This could be a possible explanation...
So we don't burn up in the atmosphere, the water cools down the planet. Technically there is more land than water anyway though since land is underneath the water. (Source)
Yes, everything is for a purpose, but not every purpose we may perceive.
Anyways, the creator knows that which we know not. And he creates as he wishes.
EDIT:
In that after careful study of the verses 68-70, we find a logic behind why Allah sends down pure water which is helpful to us, humans. So, that we remember him and thank him for his help and mercy.
Tell Me! The water that you drink.
Is it you who cause it from the rainclouds to come down, or are We the Causer of it to come down?
If We willed, We verily could make it salt (and undrinkable), why then do you not give thanks (to Allah)? (Qur'an 56:68-70)
So, here Allah is threatening us, that he could make even the rain water salty, implying, thank him enough for what ever he gave you. If Allah would have made all the water drinkable or useful, then people would rarely remember him in terms of water scarcity.
Allah it is He Who has subjected to you the sea, that ships may sail through it by His Command, and that you may seek of His Bounty, and that you may be thankful, (Qur'an 45:12)
Again, the emphasize is that we may be thankful for letting the ships sail on that salty sea water. (I couldn't find scientific references yet for this)
May the creator guide us all.
It is mentioned in Quran that everything in the universe has a purpose. So, why does Allah cover over 70% of the Earth with sea water that human beings can't consume unlike the fresh water that is helpful for humans?
That would be really bad. Yes, there would be more freshwater, but what about food sources. Humans lived from salt water fish for thousands of years, do you think that humanity would have reached the level it is in today if it was not for salt water? People have been making seawater drinkable at least as far back as the ancient Greeks. But when taken to the scale of cities, states and nations, purifying seawater has historically proven prohibitively expensive, especially when compared to tapping regional and local sources of freshwater. However, as advancing technology continues to drive costs down and freshwater continues to grow scarcer and more expensive, more cities are looking to seawater conversion as a way to meet this vital demand. One we have the technology we would have fresh water and the creatures of salt water, a win win, something that wouldn't have happened with fresh water.
Another important reason mentioned already is traveling. Salt water makes commerce and travel possible, before the age of Airplanes (which is pretty new). Imagine the exploration that would have not been done if it was not for salt water.
The third and most important reason I can think of is pretty plain, salt. Without salt water we wouldn't have had salt. Now imagine a world without salt or its benefits.
Many other ecological reasons mentioned on this sister site: https://worldbuilding.stackexchange.com/questions/14947/what-if-the-seas-had-fresh-water-in-them
Sources:
I appreciate Nadeem Khan's logical and scientific counter that water cycle has made water salty in sea after long process and time. At the origin of earth all water was pure. If we don't know the answer then we should not retrofit and attach every natural process to allah. Then why to study Science and technology. Just put everything on allah and wait for miracles to happen. Do you think we are too much dependent on allah and Quran.
