Absolutely! If you buy CO2 rights, you reduce the emission space for companies and you send an important political signal. You then show that citizens find it important that the system works, and that companies should emit less CO2.
It is important that many people, companies and institutions become involved in the system. Climate change affects everyone in society, so that is why you and I must also be part of the discussion surrounding emissions trading. Politicians must know that they cannot sit back, but that they have to work hard to ensure that the emissions trading system works much better very quickly. That is the biggest impact of your CO2 rights purchase.