For more than a decade, an international treaty has pushed along renewables and helped prevent nearly 1.5 billion tonnes of greenhouse gas emissions from harming the earth's atmosphere.
But the future of the UN system that helped emissions-cutting projects from solar farms to efficient light bulbs is now at stake.
At the centre of the debate is the Kyoto Protocol, the agreement to curb emissions among 37 nations that expires next year. The last round of negotiations to hammer out a replacement agreement is next month.
"There is a strong desire from all sides to see a final political decision made," Christiana Figueres, the executive secretary of the UN Framework Convention on Climate Change, said this week in Panama.
But nations including Japan and Russia say they are not willing to sign up for another go unless the agreement puts a limit on the emissions of major economies such as China. Their reluctance to extend the Kyoto agreement, as well as the US's refusal to join it in the first place, may call for another approach, said Adnan Amin, the director general of the International Renewable Energy Agency (Irena).
"It's very disheartening to see that progress is so limited," he said in a recent interview. "When you have five or six of the biggest emitters in the world who are not politically able to commit to an instrument that binds them, then you have to believe that perhaps we need a different way of doing this."
One, he suggests, is harnessing the private sector. Irena is recruiting a panel of renewable energy companies and industry groups so they can be placed on equal footing with member governments. The panel could be announced as soon as next year.