A new report from the International Energy Agency has found that global carbon emissions from energy have stayed flat while economies have grown. Some analysts take this to mean that economic growth and carbon pollution are no longer linked.

However, others note that energy is not the only source of greenhouse gases -- agriculture and transportation are major emitters -- and that low natural gas prices in the United States have displaced dirtier coal, a feat other countries cannot replicate as easily.

A coal barge on the Rhine River in Bonn, Germany