CNN: As governments from more than 190 countries descend on Paris next week to negotiate a new climate change agreement, they will have to consider both scientific and political realities. But to come up with a plan that works, they will need to fully grasp how climate change is already affecting the lives of people like Mathilda, a schoolgirl growing up in one of the poorest regions of Kenya. Mathilda, 15, is Turkana, an indigenous people that has survived by raising livestock in a semiarid region bordering...