I wouldn't attribute the lack of progress to the relatively new carbon tax. The carbon levy is in effect and will be scaling up in increments of 15 megatonnes per year. It's intended to achieve behaviour modifications, so you won't flip a switch and see a carbon levy having an immediate effect on emissions. It's more of a long-term trend.
I can't say for sure what the effect will be. I can't say what the magic number is for the amount, because it depends on all of the other programs the federal government is implementing—