EDMONTON -- The Alberta government is tweaking its greenhouse gas reduction rules.

Large businesses will be forced to reduce the intensity of their CO2 emissions by 20 per cent by 2017.

That means they'll have to cut the amount of gas they release in relation to the amount of product they create by one fifth.

They'll also have to pay $30 for every tonne of CO2 they release that's over that level.

Environment Minister Shannon Phillips said these are meaningful steps toward a better climate change stategy for Alberta.

"Some will argue that we aren't going far enough on these issues. I say to them we are serious about making progress," she said Thursday.

"Some will argue we are moving too far and too fast. I say to them that more of the same would be the worst thing we could do for our energy economy and for the future of our province."

These changes are significant increases over current levels and penalties.

Alberta's overall emissions are still forecast to rise over the next two years.