I'm traveling the world in search of the human face of the impacts of climate change. I encountered a sobering example yesterday, in Carhuaz, Peru. There, I met Juana, a middle-aged woman dressed in a white embroidered shirt, orange skirt and a grey felt hat. One Sunday morning in April 2010 Juana puttered around the rustic house she rented by a stream on the outskirts of Carhuaz, at the base of Peru's Cordillera Blanca range. The day, like every Sunday in Carhuaz [pronounced car-WHAS], a bustling town of 60,000, was market day [...]