Sicarius, first of all, you must realise that corruption rarely helps you in a Capitalist society (Intel, for instance, has been fined to the tune of over 1% of the value of itself for corruption). Secondly, you must realise that it is rarer than you think, and thirdly, you must not confuse corporatism with capitalism.
Environmental issues are equally easily solved under capitalism. Just as we need government for maintaining street lights, we need government to maintain the environment, stopping pollution. The way you do that is to, on an international scale, agree acceptable levels of emissions, and then make it so that companies have to buy the right to emit these pollutants. That way, those companies that can most easily change will, those that can't will pay for it. Then, slowly reduce the quotas, so companies will do everything they can to change, or else, close down.