The US is no longer the biggest greenhouse gas producer in the world. And Obama’s aggressive new plan would only reduce global carbon levels by around one percent. So why is it being hailed? Because it could spur the rest of the world into action.The US is no longer the biggest greenhouse gas producer in the world. And Obama’s aggressive new plan would only reduce global carbon levels by around one percent. So why is it being hailed? Because it could spur the rest of the world into action.