The Australian carbon trading scheme is not a good idea. One major concern is that property rights would be given to people or organizations who pollute a lot and also give them free permits. Additionally, carbon emissions would only decrease by approximately fourteen percent by the year 2020 which is not a large enough decrease.
Carbon trading is a dumb idea in general. Carbon is knowingly bad for the environment, but humans are within their right to burn it. If you want to burn a massive amount of carbon and it gets into your countries environment that is fine, but buying carbon credits is a pathetic way to justify ones actions.