AUSTRALIAN aid agencies are getting on board the global climate change wagon as governments and private companies line up to pour money into environmental projects that will earn them carbon credits.

World Vision, Australia's largest aid agency, hopes to secure millions of dollars in donations from the international carbon trade market, estimated to be worth $US120 billion ($158.5 billion). It estimates it could raise $8million by delivering environmental development projects in Africa and Asia.

World Vision chief executive Tim Costello told The Weekend Australian: "It is a sweet spot for aid agencies right now, as there are very significant dollars starting to flow from donor governments and companies. We're on the front foot on this because we see it as poverty relief.

"The money World Vision gets for carbon offsets, for example, is used to benefit people through the planting of trees that are also a food source." Or, he added, to improve crop yields through better water supply to arid areas, but doing it in a way that reduces wastage.

World Vision was the first non-government agency to negotiate a deal with the World Bank for carbon-commission offsets for a reforestation project in Ethiopia.

Nationals senator Barnaby Joyce questioned the long-term viability for poor countries that might become dependent on carbon trading.

"Carbon trading is an amorphous concept based on the idea that you can trade in odourless, colourless gas, and I'm not convinced that it's the pathway out of poverty for developing nations," he said.

Mr Costello denied any suggestion the agency was moving away from its core business in alleviating child poverty.

He said donations made to World Vision's child sponsorship scheme would not be redirected to climate change work.

The agency has set up a separate environmental donor program called Twice as Green, whereby people can pledge money each month for tree planting. While World Vision was not a scientific organisation, Mr Costello said, it had to listen to what experts were saying about the threat to health posed by climate change.

This week, British medical journal The Lancet published a report that warned climate change was the biggest health threat facing the world.

Researchers from the University College of London found that the indirect effects of climate change on water, food security and extreme climatic events were likely to have the biggest effect on global health.

Oxfam's acting executive director, James Ensor, said World Vision is not alone in its intervention into the climate change debate. Most aid agencies are now incorporating the impacts of climate change into their plans and activities on the ground.

“Development agencies like Oxfam can’t afford to ignore estimates that up to 200 million more people will be at risk of hunger if global warming exceeds 2 degrees,” Mr Ensor said.