[Paul Chapman]

Paul Chapman  asked the Naked Scientists:
   
If all the salt water turned to fresh water and the fresh water turned into salt water... What would be result for All Life??

Any chance of sending the answer to this email address

Thanks

Paul
What do you think?

[evan_au]

Adults of a few estuarine species that can flexibly move between fresh and salt water would probably be okay.
But other freshwater and saltwater species would be in trouble.

Humans would be in trouble, since our existing drinking and irrigation supplies would become unusable. Only desalination plants would benefit, because they can now use much less electricity.

This situation would not be permanent.
- salt does not evaporate with water vapour. This means that rain is always fresh water, as are rain-fed streams and lakes   
- as freshwater streams run through soils, they dissolve salts. They carry these salts down to the sea (or land-locked salt lakes)

So, over time, the oceans grow progressively saltier, while rain-fed streams remain quite fresh.


Of course, we know of nothing that could reverse fresh and salt water.