Senator BIRMINGHAM (South Australia) (14:27): I thank the minister for the answer. Mr President, I ask a supplementary question. Given the European ETS is forecast to continue trading below A$15, isn't it highly likely there will be a multibillion-dollar drop in carbon tax revenue in 2015-16 when the shift to a floating price happens? And, given that the majority of spending under the carbon tax is fixed, as the minister admitted in her Sky News interview on Sunday, won't this lead to a multibillion-dollar budget black hole? Isn't there just as much chance of the carbon tax having—to use the minister's own words from Sunday—a very negative effect on the budget when this shift occurs?