The rainy Asian monsoon season waters crops for nearly half the world's populationbut it may not be as reliable as we think. Scientists at Columbia University's Lamont-Doherty Earth Observatory are reading the growth rings of ancient trees to understand the history and workings of the monsoon. What they are seeing sheds light on past civilizationsand possibly on the future.
Written and Narrated by Kevin Krajick
Produced by Arif Noori