The Morrison government could be forced to justify Australia's plan to count "carry-over credits" towards the country's Paris climate target, with a global summit set to debate eliminating their use.

The 25th Conference of the Parties (COP25) meeting in the Spanish capital of Madrid is scheduled to debate the so-called "rulebook" for the goals agreed by the nearly 200 Paris signatory nations.

Energy Minister Angus Taylor (right) will be defending Australia's carbon emissions targets, including the plan by Prime Minister Scott Morrison (left) to use so-called Kyoto carryover credits to count against the Paris target. Credit:Alex Ellinghausen

According to the draft "guidance on cooperative approaches", one "option" for debate will be that "Kyoto Protocol units, or reductions underlying such units, may not be used by any Party toward its [nationally determined goals]".

The Morrison government has repeatedly said Australia is entitled to use "surplus" units the country will generate during the Kyoto period (2008-2020) to count against the 2021-2030 Paris target.