An Australian campaign to get other nations to accept its definition of carbon dioxide emissions has so far failed, raising doubts over whether Prime Minister Malcolm Turnbull can easily deliver the 5 per cent cut in emissions his government has promised. 
At stake is whether Australia will be deemed by the United Nations to be on course to reach its goal of cutting emissions by 5 per cent by 2020 (compared with 2000) - as the government says will comfortably be achieved - or whether they are actually calculated to be rising.
"Regrettably, no agreement on draft decisions on the methodological issues under the Kyoto Protocol could be reached despite investing a great amount of time in the particular item," a statement from the conference said, adding it would affect "the decision on the organisation of the review of inventories and initial report of Annex I Parties [of developed nations] under the Kyoto Protocol."
It is understood that a plenary session on Friday will be the last chance to resolve the impasse that remained after negotiations ran late on Thursday without a breakthrough. Without an agreement over the definition of emissions at Paris, there may not be another chance until   June.
Key developing nations agreed on a 2015 deadline for a new global agreement at the Durban gathering in 2011 in part because the European Union and Australia signalled they would make progress on ratifying the second phase of the Kyoto Protocol. A meeting in Bonn next   June may be the next time this issue will be revisited.
It is understood that not delivering on this part of the Paris negotiations means the EU and Australia have broken their part of the 2011 deal.
As reported by Fairfax Media, Australia met resistance during the Paris summit to the inclusion of deforestation in the definition of emissions covered to 2020. Including deforestation allows Australia to meet pollution goals even as emissions from industrial and other sources rise.
A postponement to   June could embarrass the Turnbull government after the Prime Minister on Monday told more than 150 world leaders Australia would ratify the second phase of the Kyoto Protocol, a legally binding treaty to cut emissions.
The impact of an unfavourable definition, were Australia to accept it, would be in the order of 60-120 million tonnes. By comparison, the government's $2.55 billion Emissions Reduction Fund has spent almost half its money paying for 92 million tonnes of abatement.
One delegate described how the team was being put under "enormous pressure" by Australian negotiators. The delegate also noted such talks are typically held by technical experts, but the Australian party had lawyers trying to press acceptance of their definition of emissions.