CREDIT: Shutterstock The world’s collective capacity to generate renewable power grew at its fastest annual pace ever last year, the Guardian reported on Thursday. But underneath that finding, there’s also an uncertain future for green power and the world’s chances of containing global warming. The numbers, drawn from a new analysis by the International Energy Agency (IEA) — a Paris-based agency that pursues the goal of reliable, affordable and clean energy for its 29 member countries — show that renewables like wind and solar now produce 22 percent of the world’s electricity, and will likely rise to 26 percent by 2020.