Martin Grosjean is a professor of paleoclimatology at the University of Bern in Switzerland and former director of the country's National Center for Competence in Research on Climate Change (NCCR Climate). Grosjean and his colleagues at NCCR Climate engage not only in research, but also in education, and one of the main activities is a summer school each year at which a group of leading PhD students from around the world converge to delve into a particular climate-related topic. On several occasions, the summer school has taken place in the town of Grindelwald, a picture-perfect ski and summer resort at the foot of some of the Alps' most impressive mountains, in a valley where glaciers converge. The Grindelwald valley has an amazing natural history, one that is tied to climate change, something that the students in the summer school have the opportunity to learn about. One afternoon during the week, Grosjean guides the students on a hike up the side of one of the mountains, showing them how to see the signs of the last Ice Age and the fast glacial retreat of the past several decades. Indeed, Grosjean and his team have turned the walk into a guided tour that anybody can enjoy simply by downloading an app onto your iPhone: at various points along the trail, your iPhone will tell you what to look for, to see the signs of climate change before your eyes.

But Grindelwald also holds an important human history, something that Grosjean explains to the students but that doesn't appear on the iPhone app. It concerns the history of farming, the town's primary economic base for all those centuries before the tourists arrived. With cowbells tinkling on the hillsides during the spring and summer months and with locally produced cheese to be found in the mountain restaurants, agriculture is still one of the reasons that the tourists come, at least for the half of the year when the grass is green.