"there are likely periods of stability where the earths various systems interact to achieve relative balance in between periods where life runs amock and almost wipes itself out."
I would say harmony instead of balance... however, this has occurred when a species, (animal or plant), growth outstrips resources. Eventually the population crashes... with luck, the survivors once again reach equilibrium with the environment at some point regaining footing.
"Ward's idea of man having to take charge of managing the planet on a huge scale gives me more than a little pause."