Solar panels will be a booming industry, says the report
The UN says millions of new jobs will be created worldwide over the next few decades by the development of alternative energy technologies.
More than a million people already work in biofuels, but a UN report says that could rise by 12 million by 2030.
It says "green jobs" depend on a shift of subsidies from oil and natural gas to wind, solar, and geothermal power.
New jobs could also include the expansion of recycling and making environmentally friendly vehicles.
The report, 'Green Jobs: Towards Decent Work in a Sustainable, Low-Carbon World', was commissioned and funded by the UN's Environment Programme (Unep).
It says the manufacture, installation and maintenance of solar panels should add 6.3 million jobs by 2030, while wind power should add more than two million jobs.
Unep director Achim Steiner said that if the world did not transform to a low-carbon economy it would "miss a major opportunity for the fast tracking of millions of new jobs".
The report was written before the current global economic crisis.
However, Mr Steiner said that to ditch green energy policies because of the crisis would be a mistake because in the long term the new jobs will make economies stronger and help make goods with less oil and gas.
Solar powered vehicles are already being developed
Late next year, delegates from around the world will try to reach a successor agreement to the Kyoto Protocol to control climate change, in a UN meeting in Copenhagen.
But Mr Steiner said the movement toward green jobs would happen whether there was an agreement or not.
He said that was because the world's population is heading toward eight or nine billion by 2050, and resources like metals, oil and gas are becoming more expensive to find.
If the world waits 10 years to take serious action on greenhouse gases the costs for moving to a green economy will be much higher, he said.
Workers 'at risk'
The report raised concerns for those involved in the manufacture of biofuels - fuels made from renewable sources such as plants or plant-derived material.
"Much of the employment on sugarcane and palm oil plantations in countries like Brazil, Colombia, Malaysia and Indonesia is marked by poor pay and dangerous working conditions," it said.
"There is also concern that large-scale biofuels production might drive large numbers of people off their land in future years," it said.
"Close scrutiny" will be needed to determine what portion of biofuel jobs can be counted as decent jobs, it added.