When you go to a doctor and the doctor gives you information about your body, the doctor makes a crucial assumption: Even though you are not a medical expert you do know the basics about how your body’s organs work. The heart pumps blood, the lungs pump air, the brain thinks, the liver filters. But I have found that few possess the equivalent level of understanding about the “organs” of the planetary physiology and the globe-connecting metabolic pathways that go in and out, to and fro, among the oceans, soils, air, and all living things.Perhaps what gives CO2 within the carbon cycle the power to serve a great entry point into a systems view of global warming and issues about the human future is the simple fact that carbon is material. Carbon can be made tangible to the mind as it moves among the organs of the biosphere. Our bodies are made of carbon. So are the trees. Carbon is in the ocean and used by the myriads of tiny green plankton. Carbon is definitely the “heart” of biological molecules, such as carbohydrates, fats, proteins, and DNA. I have found that when people learn about the fascinating global web of the carbon cycle and then see how huge has been the human-induced change in the atmosphere’s CO2, then related issues become much more salient and easier to get across: how the greenhouse effect works, why sea level will rise, why summer crops might dry out, why ecosystems will have to be managed to make the transition to a new climate, and why we need to re-think our energy systems as the global economy develops at 3 percent per year via what I call the global industrial growth automaton, for short, GIGA.In offering this book, I wear two hats. The first is that of a scientist. The second is that of motivated writer. In addition to my work over several decades as researcher and educator, I am also a person dismayed that technological society has become addicted to the fossil fuel drugs. It is highly likely that the GIGA will keep on its seemingly inexorable path, sending the CO2 higher and higher until climate change reaches future stages that are unacceptable and virtually irreversible.There is only one atmosphere, and we all, more or less, contribute to its chemical state. I try and let the facts about the conditions speak for themselves. I try to avoid any temptation for hysterics or distortions. The facts themselves lead me to conclude that we do have time to make the changes, but that they will be difficult because of the scales involved. Almost counter-intuitively, quite different but still reasonable possibilities for emissions make relatively small differences in atmospheric CO2 by 2050. The technological momentum inherent in each of those possibilities, however, make huge differences in the decades after that. Overall, we have not yet provided ourselves with enough options.But there is also room for celebration, because the carbon cycle is one of the wonders of the universe, as worthy of careful exposition for the general public as any of the discoveries of astrophysics or brain science. One of my goals is to make the carbon cycle as real as your eating and breathing.