Almonds, water and the paradox of value

Anybody following the news about California might think, on the surface, "Wow, time to get serious about global warming." Anybody who's read a few stories and has an inclination towards speculative behaviour might think "Ah, time to buy almond futures!" And finally, anyone who's read some basic economic history might stop and reflect upon Smith's 'paradox of value'. I will expound briefly on the latter two - avoiding the global warming (or 'climate change') debate. I simply am too confused about ...