It would be mistaken to suggest that the Libertarian Party platform (the current version of which I assembled in 2008) does not recognize negative externalities as coercion. Here are some platform quotes to set the record straight:
- Protecting the environment requires a clear definition and enforcement of individual rights in resources like land, water, air, and wildlife.
- The owners of property have the full right to control, use, dispose of, or in any manner enjoy, their property without interference, until and unless the exercise of their control infringes the valid rights of others.
- Government exists to protect the rights of every individual including life, liberty and property. Criminal laws should be limited to violation of the rights of others through force or fraud, or deliberate actions that place others involuntarily at significant risk of harm. We support restitution of the victim to the fullest degree possible at the expense of the criminal or the negligent wrongdoer.
P.S. The right to private property, like most or perhaps all rights, cannot be practically realized without government (i.e. a monopoly on rights adjudication), but it's silly to conclude from this that property rights are arbitrary, or should be subject to the whims of the minority (or majority) that dominates the government.