The Earth faces some big challenges including air pollution in many parts of the world, water availability and quality, as well as sanitation issues, climate change and a growing gap between rich and poor populations. Although none of these challenges are likely to be news to anyone, we will examine them in more detail, quantify them and look at some projections for the future. We will specifically address the role of various engineering disciplines in providing solutions, leading us to the concept and academic programs known as Humanitarian Engineering.