Repeatedly that the g20 must lead the way in dramatically stepping up climate action. i'm joined now by noah diffenbaugh, an american climate scientist and professor at stanford university. thank you forjoining us here on bbc news. we heard about the political and legal ramifications of this ruling but were interested in the climatic impact of these really potentially. how significant is it? ., ., , potentially. how significant is it? ., ., y , a, it? not only is global warming happening _ it? not only is global warming happening but _ it? not only is global warming happening but the _ it? not...