Federal cabinet has not agreed on a final position but Mr Morrison is expected to use his speech to the British gathering,which he will deliver online,to go further than his most recent remarks on reaching the 2030 target without the credits.
"We will only use that carryover,though,to the extent that is required,"he said in a speech to the Business Council of Australia on November 19.
"Let me be very clear. My ambition[and] my government's ambition is that we will not need them. And we are working to this as our goal,consistent with our record of over-delivering in these areas."
The latest figures on Australian greenhouse gas output showed the emissions fell to 513.4 million tonnes in the year to June,down from 529.5 million the previous year,an annual fall of 3 per cent and the lowest level since 1998.
The COVID-19 pandemic and recession have been major factors,withtransport emissions falling to 19 million tonnes in the June quarter from 24.2 million in the March quarter due to social restrictions and a collapse in travel.
The official figures,released last Monday,came with an estimate that Australia would beat its 2020 target by 459 million tonnes including carryover credits and would beat it by 316 million tonnes without relying on those credits.
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The target for 2020 was to reduce emissions by 5 per cent from the level in 2000. The target for 2030,set by the Abbott government five years ago,is to reduce emissions by 26 to 28 per cent on the level in 2005.
Energy Minister Angus Taylor said on Monday the latest figures showed national emissions were already 16.6 per cent below the 2005 level,putting Australia on track to beat the Paris target.
Greenpeace responded by calling on the Morrison government to commit to"100 per cent renewables"and net zero emissions by 2040.
Britain's Conservative government has committed to net zero emissions by 2050,a target matched by Japan,South Korea,France and New Zealand.
Labor leader Anthony Albanese has pledged to deliver net zero emissions by 2050 if he wins the next election,but Mr Morrison has refused to offer a similar pledge despite arguing the target could be reached.
One government MP,Warren Entsch from the seat of Leichhardt in Queensland,argued in favour of a net zero target for 2050 in the Coalition party room on Tuesday,but the issue has the potential to revive years of Liberal and National division on climate targets.
Mr Morrison's plan to meet the 2030 target without carryover credits clears the ground for a stronger ambition on net zero emissions beyond his current stance of meeting the longer-term target some time after 2050 and before 2100.
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Mr Johnson,Mr Guterres,French President Emmanuel Macron,Chilean President Sebastián Piñera and Italian Prime Minister Giuseppe Conte sent Mr Morrison and other world leaders a letter in October calling for more action ahead of the December 12 meeting.
"There will be no space for general statements,"the group said.
The letter said speaking slots at the gathering,to be held on the fifth anniversary of the Paris accord,would only be allocated on the basis of"ambitious"new commitments on emissions reduction,strategies to achieve net-zero emissions,new finance commitments or adaption plans.
Mr Johnson will this weekend announce the UK's new goal to cut 1990-level emissions by 68 per cent by 2030,up from the existing target of 57 per cent.
The new target would bind Britain to reducing its emissions by the fastest rate of any major economy to date,the Prime Minister said.
"But this is a global effort,which is why the UK is urging world leaders as part of next week's climate ambition summit to bring forward their own ambitious plans to cut emissions and set net zero targets."
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