 Here's CBS News correspondent Christopher Cruz. Dr. Amir Sapkota chairs the Epidemiology and Biostatistics Department at the University of Maryland School of Public Health. These heat waves are more common, and when they do happen, they tend to last longer, and they are a lot nastier. Dr. Sapkota notes the heat wave in Europe last summer killed between 50,000 and 85,000 people. He says that should be a wake-up call.