The largest threat currently faced by humankind is the ever-rising CO2 levels in the air we breathe. In our lifetime, the CO2 level has increased by 33% from 300ppm to 415ppm. The limit for the indoor CO2 level that is without risk to humans is somewhere between 1000 and 2000ppm. Bill Treneman at UPC Cambridge showcases how we have perhaps only 200 years until human health is affected by the CO2 that we breathe in the air, if humans do nothing to change current trends.