A HIGH level of immigration means Australia won't be able to cut its greenhouse gas emissions, an academic paper claims.

The population is forecast to rise by 6 million people to 25 million between 2000 and 2020.

Over that time the Federal Government wants to cut emissions by 5 to 25 per cent.

But the extra people means more emissions, according to the paper issued this week by Monash University's Centre for Population and Urban Research.

The population growth, most of which would come from migration, meant more people to be housed and employed, and bigger cities.

"Rapid population growth ... makes the attainment of even the most modest reductions to overall greenhouse emissions in Australia very difficult to achieve,'' said the paper, authored by Bob Birrell and Ernest Healy.

There was little prospect Australia could cut emissions by the minimum 5 per cent, let alone anything more ambitious.

But there was a "relatively painless'' solution - stabilising the population.

The paper's authors calculated that if the Government did not take steps to reduce emissions, emissions would grow by 40 per cent by 2020, and 83 per cent of that increase would come from the extra people.

The Government wants more people because it means more young taxpayers as the rest of the population ages.

Treasury projects the population will rise to 33 million by 2050.

Meanwhile, the Australian Greens have called on the Government to take the lead in the next stage of world negotiations on climate change.

Under the deal reached at the troubled Copenhagen climate summit in December, countries are supposed to announce their targets to reduce emissions by the end of this month.

Australia previously planned to reduce emissions by 5 to 25 per cent but could refine this target in light of the lack of progress at Copenhagen.

The Government has kept mum on what its new target will be, preferring to wait to see what other countries are doing.

Greens leader Bob Brown said Australia should announce a 25 to 40 per cent reduction by 2020.

"We should be leading, we should have that target up there and announced,'' Senator Brown told reporters in Canberra.

"But instead of that the Rudd Government appears to want to wait and see what Togo, and Somalia, and Nepal and Timor are going to do before they act.''



Originally published as Immigration 'will fuel greenhouse gas growth'