The circumstances that will shape the long-term future of our planet will be constrained by what is physically possible and what is not. This book provides a quantitative view of our civilization over the next 100,000 years, in comparison to the 40-60,000 years it took for modern humans to emerge from Africa, on the basis of contemporary scientific and technological knowledge. The first 5 chapters provide the general scientific background, starting with a brief history of our planet, from its formation 4.5 billion years ago until the present day. The evolution of the Earth''s atmosphere and the origin of water are highlighted as being the most important factors for the emergence and the development of life, especially in comparison to Earth''s neighbours, Venus and Mars. The authors then consider both cosmic and natural hazards, pointing out that scientific information provided by satellites and communication systems on the ground could prevent many unnecessary casualties by forward planning and the installation of elementary precautions.
The changing climate in the past and in the future is considered, showing how atmospheric greenhouse gases CO2and methane played an important role in past climates, whereas future human industrial and agricultural emissions of greenhouse gases largely determine the future climate. The authors highlight the importance of long term monitoring and control of the atmospheric composition. Chapter 7 looks at future energy and inorganic resources, the needs for which in the year 100,000 will be five times larger than the present ones. The most likely sources will be from fusion, solar and wind energy, and storage facilities will be needed for the latter two. Water, agriculture and forests are considered in the following chapter: although adequate food and water should be available worldwide, inadequate management may cause some densely populated areas to experience shortages.
The colonization of other planets, in particular Mars and Venus, and the possibility of extracting resources from the Moon or asteroids are discussed in Chapter 9. The final chapters stress the importance of international collaboration to manage Earth''s future, together with the crucial role of space for its monitoring, surveillance and management. Cooperative world governance and global laws should be undertaken by the political, scientific and space worlds and encompass both the rich and poorer countries.
