Are there any safety guidlines about how high you can climb a tree? For example, we have a lot of very tall pine trees where the limbs are all near the top of the tree. Obviously, if you try to climb to the very tip, some part of the tree is going to break and could cause an accident. I imagine that different factors such as the height, diameter of the tree at the height, climbers weight, wind speed, ... would all affect the safe height. Are there any guidelines to say how high would be safe or not safe?