Desalinating seawater around the world contributes to CO2 emissions, and requires burning a lot of fossil fuel. Look at where they are and know that what powers the process is nasty: http://tinyurl.com/y8whz6rj
But not having water is much nastier.
I think the pursuit of the "science" of global warming should be cut back 90% (i.e. arbitrarily a lot), and that those who push that "science" should be put to work planting trees, paid at $15/hr. minimum wage, side-by-side with persons of challenged upbringing (OK, drugs addicts, thieves and more). In this way much good would happen, and the "researchers" world-wide would actually be doing something to address the issue, instead of profiteering on the issue while adding to the issue with their reports which cause global warming through paper use, computers bought, car/plane travel not needed otherwise, etc., etc., ad nauseam.
The effort to "prove" warming is currently doing exponentially more to add to the subject than it is to solve it.