This book considers how our human journey to where we are today, and where humanity will go in the future, are driven by consequences of the 2^nd Law of Thermodynamics. It puts into perspective how the human population has exploded to take over the Earth, and how the "bronze age" and "iron age" transformed civilisation. It helps us to understand what happens in our own atmosphere, and the atmospheres of other planets. It provides guidance on how technology might address water scarcity affecting many parts of the world, and how food production might be sustained and expanded in a period of changing climate and an expanding global population.