Capitalism is always the way to go over socialism and especially when it comes to the environment. Capitalism will help the environment sustain itself through growth and prosperity, and if it is worth keeping the environment will be saved. Too little gets done with socialism, which will hurt the environment in the long run.
While capitalism is said to eliminate waste from industry, it does not. Without regulation, businesses generally go for short term to medium term profit. Safety and environmental health are expensive, but necessary. With unregulated capitalism, industry ships waste overseas, pollutes the air with toxic gases, and releases poisons into the environment. Socialism (and some mixed systems) enforce regulations on environmental hazards. Places with socialist (or more collectivist) governments have better environments. Sweden and Norway for example, have much healthier environments than the USA (even taking into account population and size differences). When it comes to profit, capitalists don't think of environmental prices.
Regardless of my personal beliefs on what might be better for the people (a mixture of many political systems), socialism is by far better for the environment. It takes into account the need for a shared land and resources among the people. Capitalism on the other hand allows individuals or private entities to take advantage of the resources for their own means. Whether their intentions are good or evil is not the question, as in capitalism it is only whether it is profitable.