The United Nations Organization defines climate change as the global variation of the Earth's climate. This variation is due to natural causes and human action and occurs on all climatic parameters: temperature, rainfall, cloudiness, etc., at very different time scales. One of humanity's most important challenges is to face climate change induced by frenetic human activity. For our planet to arrive in acceptable conditions for future generations, it is necessary to take measures. Polluting emissions from fossil fuels are the main cause of such climate change. It is clear that we must try to replace them with clean energy (without polluting emissions) and renewable energy (that does not run out). This book includes solved practical exercises, tables with data of interest, diagrams, graphs, photos, etc. Explanations are also given about the greenhouse effect, acid rain, the ozone layer, the carbon cycle, the ecological footprint, etc. It is a reference book of great interest for the general public, official bodies, equipment manufacturers, training courses, energy agencies, engineering, installers, investors, etc. ÍNDEX: Chapter 1 CLIMATE CHANGE AND THE UNITED NATIONS. Chapter 2 CLIMATE CHANGE AND FOSSIL AND RENEWABLE ENERGY.Chapter 3 REDUCING THE EFFECTS OF CLIMATE CHANGE. Chapter 4 ENLARGEMENT OF FOREST AREA. Chapter 5 FOSSIL AND RENEWABLE ENERGY. Chapter 6 ACID RAIN. Chapter 7 THE GREENHOUSE EFFECT. Chapter 8 THE CARBON CYCLE. Chapter 9 THE OZONE LAYER.