The federal Coalition has confirmed it will dump Australia's commitment to reduce emissions by 43 per cent by 2030, arguing it is unachievable.
Australia has committed under the Paris Agreement to cutting greenhouse gas emissions by 43 per cent on 2005 levels by the end of the decade.
Abandoning the target would also mean withdrawing from the Paris Agreement.
The Coalition argues Labor will fail to meet the target, while significantly damaging Australian industry in the process of trying.
But it remains committed to reaching net zero emissions by 2050, arguing nuclear power should play a key role in getting there.
Shadow Energy Minister Ted O'Brien said the cost would simply be too great.
"If Labor is going to achieve its 2030 targets, which industry is it going to attack?" he said.
"Is it manufacturing, is it agriculture, is it resources?
"The only way now that Labor can achieve its 2030 target, is to collapse industry. We will not have a bar of it from the Coalition."
The most recent projections from the Climate Change Authority found Australia was not on track to meet the 2030 target.
But it suggested if the government implemented policies as promised, the country could come very close to making the goal.
The heavy lifting will largely be done by the energy sector, and the government has a separate commitment to run the national grid on 82 per cent renewables by 2030.
The Coalition argues that too will be impossible to meet, and is preparing to detail a very different energy policy — relying more heavily on gas, while nuclear power plants are built on the sites of retired coal-fired generators.
The release of that policy has been repeatedly delayed.
Mr O'Brien was pressed on whether the Coalition would adopt any targets at all before 2050, but was unwilling to say.
"When it comes to our energy policy — that will be released in due course," he said.
"But we will not accept from Labor an ongoing dishonesty, trying to tell the Australian people that everything is going well.
"This is turning into a trainwreck for our economy."
The federal government has heavily criticised the announcement, arguing it risks Australia's international reputation and certainty for industry.
It says there is simply no way to revise the 2030 target backwards without withdrawing from the Paris Agreement.
Energy Minister Chris Bowen said the Coalition needed to spell out how it would handle that.
"The Paris Accord is very clear — you can't backslide, you can't reduce your commitments," he said.
"So is [opposition leader] Peter Dutton proposing to leave the Paris Accord, or is he just hoping no one notices?
"At the moment, the countries outside the Paris Accord are Libya, Yemen and Iran. Is Mr Dutton proposing to take Australia into that company?"
The Coalition argues Labor is going to fail to meet the 2030 target, and needs to make its own explanations as to how it would meet the Paris commitment.
The announcement has also been criticised by climate groups, who argue Australia is building momentum towards reaching the 2030 target.
Jennifer Rayner from the Climate Council said dumping the targets would be a step backwards.
"Peter Dutton is talking about doing a huge U-turn on the momentum and progress Australia is already making," she said.
Kelly O'Shannessy from the Australian Conservation Foundation said the cost of abandoning the targets would be significant.
"Mr Dutton's plans would be an international disgrace and it would trash our relationships with key allies who are depending on Australia to adhere to keeping 1.5 degrees alive," she said.
"Mr Dutton is also banking on a nuclear fantasy which Australia does not need and Australians do not want it."