So, I can feel a theme developing here...
It seems that 'green' is the new 'black', as the environment becomes an increasingly fashionable topic. Environmentally-friendly and ethical living was once the preserve of eco-warrior Swampy and some trendy rock stars. Now the politicians have muscled in, and these issues are fast loosing their street cred, but they are also - more importantly - becoming more prolific among ordinary people like you and I.
I've been vegetarian most of my life, done my best (mostly) to recycle and to buy products that aren't tested on animals. For years I thought that made me an ethical consumer. Over time, I started buying organic fruit and veg, fairtrade tea and sugar, and using energy-saving light bulbs. I walk to work, I read my newspapers online, and do my best to conserve energy at home. But I know all this is not nearly enough.
What has struck me with most of these steps is how much more they have cost me. Now, this is a cost I choose to absorb. I'm prepared to pay more in order to limit my impact on the environment, and support 'ethical products'.
Unfortunately, not everyone is in such a privileged position. Not everyone can afford to pay more for their weekly shop. A fifth of all people in Scotland are living in poverty, and they don't have the 'luxury' of paying more for environmentally-friendly products.
Of course, there are some things we can all do to reduce our impact on the environment that cost nothing or actually save us money - such as walking rather than driving, and not leaving your TV on standby. However, most 'green choices' are more expensive.
The point to this particular ramble of mine, is that we should not forget that there are many people who simply cannot afford to live in a more environmentally-friendly way. Taxing behaviour that is bad for the environment is fine in principle, but it is a form of indirect taxation - which we all know impacts disproportionately on the poorest in society.
The solution to this is simple of course - rid Scotland of poverty! But until we are empowered to do so with independence, we must be balanced in our calls for polluter pays taxation.