An internal report by National Australia Bank seen by The Sun-Herald suggests the emissions trading debate in Australia has been dominated by claims about the short-term costs, and scant attention has been paid to new investment opportunities.

"The average year-on-year investment created by the [Carbon Pollution Reduction Scheme] could be up to 60 per cent greater than that committed for infrastructure in this year's budget," the report says.

It warns there has been "little consideration of the investment stimulus" that would be created as the economy becomes less greenhouse-intensive.

"This is unfortunate, as discussion of any costs should be balanced with an examination of the opportunities."

The modelling work traces the impact of the three possible emissions reduction targets announced by the Government.

It assumes that the price of emissions will gradually rise from from $20 a tonne of carbon dioxide to $100 a tonne as the Government progressively reduces the number of permits.

The report also assumes that 30 per cent of Australia's investment efforts to cut emissions will leak to foreign countries.

It found national investment triggered by the scheme would initially be boosted by $860 million in 2012.

Under the least onerous scenario - a mandatory cut in carbon emissions of 5 per cent below 2000 levels by 2020 - investment would be boosted by $5.8 billion a year by 2020 and by $10.8 billion by 2050, or an average of $6.2 billion a year.

Assuming a 15 per cent cut below 2000 levels, the average annual gain would be about $6.3 billion a year.

A 25 per cent cut - which will become Government policy if there is a strong international agreement an United Nations meeting in Copenhagen, Denmark, in December - would boost investment by about $6.5 billion a year, on average, over the next 40 years.

Treasury modelling produced for the Government concluded the emissions trading scheme would only have a small net impact on employment.

But the Minerals Council says the mining sector will lose 23,510 jobs over the next decade if a 5 per cent target is adopted.