Renewable energy sources could meet nearly 80 per cent of the world's energy supplies by 2050 if governments pursue policies that harness their potential, according to a United Nations-backed report released Monday.

The findings of more than 120 researchers working with the Intergovernmental Panel on Climate Change (IPCC) indicate that if the path of renewable source is fully followed, greenhouse gas emissions could stay low enough to keep the rise in global temperatures by the middle of the century to below 2 degrees.

That 2-degree threshold is a widely regarded tipping point, beyond which the worst effects of climate change are likely to occur. Governments also agreed at a major meeting last year in Cancún, Mexico, to try to limit the average global temperature rise to that amount.

The report's findings were issued today after a four-day meeting of scientists wrapped up yesterday in Abu Dhabi, United Arab Emirates, with the aim of providing policy-makers with an assessment of the potential of renewable energy sources.

Christiana Figueres, the Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC), described the report as "most significant" and said it points the way forward for governments.

‘They must reach their goal by making use of renewable energy sources on a very large scale," she said. "It is also clear that ambitious national policies and strong international cooperation are together the key to the swift and extensive deployment of renewable energies in all countries."

Ms. Figueres stressed the need for the appropriate finance and technology being made available to poor countries, which are expected to see the largest growth in energy generation in the decades ahead.

"Industrialized nations need to create the right policy conditions and incentives so that the development and installation of clean energy technologies also receive a major boost in their own energy mixes."

The report includes a review of more than 160 different scientific scenarios based on different levels of renewable energy sources and varying environmental and social factors.

Four scenarios reflecting the full range of possibilities were analyzed in depth, and the most optimistic of the four scenarios projects that renewable energy sources could account for as much as 77 per cent of global energy demand by 2050 – compared to the figure of just below 13 per cent in 2008.

That scenario would also mean a cumulative saving of greenhouse gas emissions equivalent to 220 to 560 gigatons of carbon dioxide between 2010 and 2050.

While the report concludes that renewable energy sources will increase even without enabling policies, it notes that past experiences show that the largest increases come with concerted policy efforts.

The costs of many renewable energy technologies would also become more economically attractive, the report notes, if environmental impacts such as greenhouse gas emissions and pollutants are monetized and included in energy prices.

The overall costs of most renewable technologies have also declined in recent years and the researchers found that they are likely to fall further.