Australia's Labor Party aims for carbon neutrality
Australia's Labor opposition wants the country to be carbon neutral by 2050, meaning all its emissions will need to be offset with renewable energy.
It also proposed a 2030 emissions reduction target of 45% on 2005 levels.
That is higher than the 2030 target of between 26% and 28% that the Australian government will promote at climate change talks in Paris.
Labor's targets were described as "mad" by Australia's industry minister Christopher Pyne.
Other government ministers said Labor's plan would increase household power bills.
Mr Shorten said the 45% figure would be used in consultation with industry and a full policy would be announced next year.
Commentators said Labor wanted to appear stronger on climate change than the Liberal-National Coalition government ahead of next year's federal election.
Australian Prime Minster Malcolm Turnbull will next week join other world leaders in Paris who are seeking to reach a legally binding agreement on keeping global warming below 2C.
He told the ABC he was confident an agreement would be reached.
"I am optimistic, and I notice that the French president is optimistic," Mr Turnbull said.