Climbing and drought

In my attempts to bring tree climbing events to different cities and agencies here in Colorado, I am hit with many knee-jerk objections from suits and bureaucrats. I have prepared responses to these FAQ's on my brochures and website. But a new one was thrown at me that I'm not quite sure how to answer: that climbing during dry or drought conditions overly stresses the trees and increases risk of damage. Does anyone have knowledge on this, as the West is currently in the middle of a long-term drought?