According to Herbert Girardet (author of Cities People Planet), “sustainability enables all its citizens to meet their own needs and to enhance their well-being, without degrading the natural world or the lives of other people, now or in the future (Page 6-Planet).” Cities have been at the heart of this question because it is where the human population is at its highest and densest. Just look at the history of human civilizations for example, from Jericho to Rome (Chapter 2), from Beijing to London, and from Hong Kong to New York. What do they all have in common? They are all highly populated cities and most of them are near the coastal regions where pollution and sea levels are rising due to global warming. So given that about 80 percent of the world’s population is expected to live in urban areas by the year 2050, sustainability is an extremely huge concern for our present time and the future. Should we practice it? Definitely. Sustainability is ethical for our survival, and most importantly, preserving the natural resources and ecosystem of our planet from the destruction of global warming. We have to understand the obligations, values, and consequences of sustainability because it is self-apparent as humans to practice sustainability and maintaining a livable planet. We will look at the link between humans, cities, and the natural world, why are we talking about sustainability today. Then we will look at the impact of globalization and global warming on our planet and what we can expect to happen in the future if this trend does not stop. Finally, we will look for possible solutions to our planet’s current crisis and why we should work towards an ethic of sustainability according to Randall Curren (Toward An Ethic Of Sustainability). The author Louis Mumford said 50 years ago: “If we would lay a new foundation for urban life, we must understand the historic nature of the city. (Chapter 2)” In order for us to understand the link between humans, cities, and the natural world, it helps to understand the history of how it started. The link between humans and the natural world was already apparent from the beginning. The history of human settlements starts with hunter-gatherer bands setting up temporary camps or occupying caves in areas where fruits, nuts, fish, and game were plentiful. From there, villages emerged after wheat and barley had been domesticated in the Levant around 8,500 BC. Thousands of people lived in one space by growing crops on clearly defined areas of land and fishing the fertile waters of rivers, lakes or the sea. This early settlement exemplified human control of nature through technological innovation, “with hoes, ploughs, and sickles used to farm the land and pottery jars made to store the harvest. The emergence of towns and cities is also the story of complex forms of social organization, with the appearance of formalized political and spiritual hierarchies, administrations, writing and military power (Page 24).” Subsequently, larger civilizations developed through time. Early cities like Jericho and Catal Huyuk emerged. Dating back to about 7,000 BC, Jericho had the world’s earliest city walls, stone staircase, and its sufficient water. At 7,100 BC, Catal Huyuk existed for about 1,500 years, with a 32 acre site, mud brick houses, and a population of about 6,000. There is also much evidence of long-distance trade, cowrie shells from the Mediterranean, manganese copper and turquoise from eastern Anatolia and the Sinai. Despite having the necessary ingredients to have a livable city, these early civilizations cease to exist which means that they were not sustainable. Why weren’t they sustainable? Much more excavation work is needed before we can get a clear answer on why those early cities weren’t sustainable. This transitions us into the impact of modern cities and how it is jeopardizing the sustainability of our world.