They are set to block the government’s legislation when it is put to a vote in upper house on August 13, 2009. The government plans to introduce a carbon trading scheme in July 2011.

By 2020, Australia intends to reduce its green house gas emissions by 5% of 2000 level.

The country accounts for only around 1.5% of global emissions but is the biggest per capita polluter in the developed world because of reliance on fossil fuels, chiefly coal, for 80% of its electricity generation.

Liberal- National coalition leader Malcolm Turnbull, and independent senator Nick Xenophon, in a join statement, asked the government to withdraw its carbon trading legislation and begin talks with the opposition, minor party senators and other stakeholders to design a “more effective scheme”.

“Overall, the cost to the Australian economy over the next 20 years in net present value terms is reduced by A$49 billion, or about a third,” they said.

The opposition’s scheme would also allow Australia to adopt a tougher emissions reduction target of reducing total emissions by 10% of 2000 level they by 2020.

Other changes proposed in the current carbon plan include providing a 100% shield to emissions-intensive trade-exposed industries, including coal, and auctioning around 30% of the permits required by industry – in line with the planned ratio of the Waxman-Markey scheme being debated in the US rather than the current 70%.

Frontier also recommended excluding agricultural emissions from the carbon trading scheme, allowing agriculture to contribute to emissions abatement through measures such as carbon sequestration in forests.

“This is the modeling work that the Rudd government refused to undertake,” Turnbull said. “It shows that with relatively modest changes, the proposed emissions trading scheme can be made far less harmful to jobs, investment, regions and the Australian economy.”

Climate Change Minister Penny Wong said that the baseline and credit model proposed by the opposition was flawed, and was tried, without success, in Canada.

“Turnbull is arguing for us to copy the failed Canadian experiment of baseline and credit. This is bizarre since the Canadians have indicated that they are moving towards cap-and-trade,” Wong said.

“It is not a hybrid model, it is a mongrel. It is a smokescreen,” Wong said.

As per the legislation presently before Parliament, Australia would adopt a carbon-trading system similar to one in Europe that caps carbon dioxide emissions, forcing firms to buy carbon permits to cover their emissions.