If successful, it could improve the health of the residents as well as reduce greenhouse gas emissions.

Garry Egger, a professor of lifestyle medicine and applied health promotion at Southern Cross University, said that addressing climate change provided an opportunity to tackle the linked problem of obesity.

''If people are not using their cars, and using their own person power instead, it will also benefit their health.''

Professor Egger's team has been awarded a $390,000 Australian Research Council grant to conduct a three-year study of the effectiveness of the scheme, which will start next year.

Norfolk Island residents will be allocated the same number of carbon units on a credit card, which they will spend whenever they buy petrol and power.

If they are frugal with non-renewable energy consumption, and walk, cycle or drive an electric car, they will be able to trade in leftover carbon credits at the carbon bank for cash at the end of a set period.

Each year the quota of carbon units will be reduced, and the price of a high carbon emission lifestyle will rise.

Although it will be a voluntary scheme, the incentive to participate was obvious, Professor Egger said: ''People can make money out of it.''

In the second year, the researchers hope to add food to the scheme, ranking products on their health cost as well as their carbon cost.

Fatty foods imported from the mainland, for example, would require more carbon units to purchase than local fresh produce.

''Over the three years we will be looking to see if there is a reduction in diabetes and obesity,'' said Professor Egger, who developed the GutBusters weight loss program for men.

He said the island provided a unique testing ground because it is small, people live a similar lifestyle to most Australians, and the goods that come in and out by plane and ship can be monitored.

About 30,000 tourists and other visitors come to the island each year and they will also be given a carbon credit card on arrival to participate in the scheme, and find out more about their carbon usage.

The Norfolk Island government is a partner in the project and the Minister for Tourism, Industry and Development, Andre Nobbs, said he was delighted it had been given the go ahead. ''The population has strong ideals and beliefs about the environment,'' he said.

Tourists would see the scheme as a ''very proactive step'', he predicted.

Professor Egger said he was disappointed that the two banks on the island had declined to participate, but he expected the scheme would provide lots of other business opportunities.

He has been invited to speak to business people at the United Nations climate change conference in Mexico in December.

The Norfolk Island trial will determine whether the approach is acceptable to people or not. If so, it could eventually be scaled up to a country level, and then world level, he said.