The tax is due to be replaced in 2015 by an emissions trading scheme, in which the cost of emitting a metric ton of carbon would be determined by buyers and sellers in a carbon market. Rudd has pledged to bring forward the emission trading scheme linked to the European market by a year to July 2014, reducing the cost to Australians of emitting a metric ton of carbon dioxide from AU$25.40 to an estimated AU$6. The 30 percent mining tax on the profits of iron ore and coal miners was designed to cash in on burgeoning profits from a mineral boom fueled by Chinese industrial demand. But the boom was cooling before the tax took effect, with prices for iron ore and coal peaking in 2011. The tax was initially forecast to earn the government AU$3 billion in its first year, but collected only AU$126 million after six months.