If that's not what you believe, then nothing you've said has a leg to stand on.

Because it is not the job of politics to address those issues. it is the job of the people to address that. The political structure simply delineates how. Libertarianism, and by extension, AnCap, simply says you cannot initiate the use of force to make someone comply with your wishes. That is the only restraint. You are free to use other, non-violent means to convince someone to stop clear-cutting their forest, and if they try to clear-cut yours, you can shoot 'em. If someone causes you damage through actions entirely on their property, you are entitled to recompensation.

Aside from that, libertarianism is neutral on Global Warming, resource depletion, etc.