GEF

4 Contents UNIT 3 Primary Sustainability Issues 5 6 3.1 The Central Role of Energy 58 3.2 Advantages of Renewable Energy 62 3.3 Sustainable Agriculture 66 3.4 The Green Revolution of Agriculture 68 3.5 Sustainable Water Systems 74 3.6 Industrial Pollution and Toxins 78 UNIT 4 The Global Ecosystem 8 6 4.1 Our Planet in Context 89 4.2 The Earth as a System 91 4.3 The Water Cycle and the Nitrogen Cycle 92 4.4 The Importance of Ecosystems 97 4.5 Sustainability as an Integrating Concept 99 UNIT 5 The Importance of Biodiversity 1 04 5.1 Where Does Life Exist? Defining Earth’s Biosphere 107 5.2 Biodiversity as Nature’s Risk Management Tool 108 5.3 The Benefits of Biodiversity to Humans 111 5.4 The Biodiversity Crisis: Tropical Forests and Oceans 114 5.5 Biodiversity Threats and Protection Strategies 117