An Abbott government would need to spend around $35 billion more than it has budgeted on its climate change policy to deliver its promised cuts to carbon emissions by 2020.
The findings from energy advisory firm RepuTex raise more doubts about whether the coalition's Direct Action plan can reduce carbon emissions by five per cent by 2020 given the funding allocated.
The coalition has promised to meet its target with a capped $3.2 billion fund, to be spent over four years, on activities that cut greenhouse gas emissions like revegetation and improving soil carbon.
The modelling from RepuTex - commissioned by WWF Australia - claims the coalition can meet the five per cent target, but would need to spend an extra $5.9 billion per year from 2015 to 2020.
"There's no doubt Direct Action can be an effective source of emissions abatement, the issue is the funding that's gone into it," RepuTex's Hugh Grossman told AAP on Friday.
The research claims Direct Action would lead to a surge in coal generation, reduce investment in clean energy and drive up emissions to the tune of 16 per cent on 2000 levels.
WWF climate spokeswoman Kellie Caught said this not only put the five per cent target at risk, but made it unlikely Direct Action could be ramped up to meet more ambitious goals.
Environment groups say a much deeper emissions reduction target of about 25 per cent is needed if Australia is to do its fair share.
Earlier this month, modelling for the Climate Institute estimated the coalition would need to spend between $4 and $15 billion extra to meet its 2020 target.
Opposition climate action spokesman Greg Hunt said it was clear supporters of Labor and the carbon tax had "gone into a report frenzy" with the election looming.
"This dodgy report is fundamentally flawed and goes against the government's own emissions predictions," he said in a statement.
"It has been delivered solely for a political agenda."
Mr Grossman denied RepuTex was on the ALP payroll, adding the advisory firm represented the "big boys" of the energy industry rather than any political interests.
