Climate Change Minster and Green Party co-leader James Shaw has introduced the Climate Change Response (Auction Price) Amendment Bill, and it may confuse a few people - something the Minster admits that himself.

The bill allows a confidential reserve price to be set for auctions in the New Zealand Emissions Trading scheme.

However, Herald writer Richard Prebble described the move as "tax-gathering rort".

Shaw told The Country the bill is technical.

"The previous National Government decided that we were going to start auctioning units into the ETS as part of a way of rationing the number of units available and driving down pollution, and we're executing on that."

Shaw adds the bill is a "fast evolving" beast.

"The short version is that if you can take carbon dioxide out of the atmosphere, which generally means planting trees, you ca earn some money from that. If you put carbon dioxide into the atmosphere in the form of pollution... then you pay your money, and if you do neither it's neutral."

Shaw adds currently there is not an international market for carbon.

Listen above as Jamie Mackay challenges James Shaw to explain the bill