As extreme heat blankets large parts of the US, a war is looming between the US and Mexico over water. Under an 80-year-old treaty, both sides are expected to share resources from key rivers. However, extreme drought conditions have put Mexico well behind in delivering its share. In this episode, we examine how the shortfall is impacting American farmers and look at what can be done to factor climate change into future agreements. 

Guest: Laura Paddison, CNN Senior Climate Writer