Protesters calling for the declaration of a "climate emergency" have clashed with police in Melbourne amid news the federal government is unlikely to rely on "carry-over credits" to reach its 2030 Paris emissions reduction target.
Some activists glued and chained themselves to each other and the pavement on Saturday, before being arrested by officers carrying bolt-cutters.
"Australia needs to be a climate lifter, not a climate leaner. We are about to go over a cliff but nobody seems nearly alarmed enough," rally participant Miriam Robinson said.
"It has been five years since the Paris Agreement and we are still moving far too slowly to avert global catastrophe. Australia does not even have a coherent national plan, just piecemeal policies and a lot of excuses."
Saturday's dramatic street scenes follow Prime Minister Scott Morrison's address to a Pacific Islands Forum overnight, during which he hinted the government could ditch the controversial plan to use Kyoto credits amassed before 2020.
"Australia is very confident that we will now achieve our 2030 targets without the need to draw on our carry-over credits," he told the virtual forum.
Australia's emissions are projected to be 29 per cent below 2005 levels by 2030 compared with its Paris accord target of 26 per cent to 28 per cent.
Labor climate change spokesman Mark Butler on Saturday accused the government of misrepresenting the data, saying Australia was only on track for a 22 per cent reduction by 2030.
He called for the government to commit to net zero emissions by 2050, as New Zealand has, and to work harder to meet the Paris target.
"The government's projections clearly show there will only be a reduction in emissions between 2020 and 2030 of less than seven per cent," Mr Butler said in a statement.
"At that rate, it will take 146 years to get to net zero emissions.
"Electricity is the only sector with considerable emissions reduction and that is due to state government policies and households choosing to install rooftop solar."
Pacific island nations have long called for Australia and NZ, as regional leaders, to do more on climate.
Climate is a sensitive coalition policy area and Mr Morrison has beefed up his language on the perceived emissions credits.
"Those credits that have been earned have been earned by farmers investing in changes," he told reporters in Canberra on Friday.
The forum comes days after the prime minister confirmed he would not speak at an online summit organised by the United Nations, the UK and France, a move Mr Butler said demonstrated Australia's "isolation" on climate policy.
More than 70 nations are speaking at the event, including China, which has recently committed to net zero emissions by 2060.
Greenpeace Australia said it was embarrassing the prime minister wasn't speaking at the UN summit.
Saturday's protest in Melbourne included a road block and boats on the Yarra.
"We demand that the government declares a climate and ecological emergency, and reduce greenhouse gas emissions to net zero as fast as humanly possible," Ms Robinson said.
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