Without coal, our lives would be profoundly different. Formed over millions of years, coal provides one-fifth of the energy we use today. But burning coal also produces more pollution and greenhouse gases than other energy sources, which contributes to the growing problem of climate change. In the future, it will be more important than ever to find ways to make coal a "cleaner" form of energy. The countries of North America have always had plentiful natural resources. But the exploitation of these resources comes at a cost, and in certain cases, some have wondered if that cost is too high. North American Natural Resources explores all facets of this vital aspect of our economy. Readers will investigate the natural history, human use, technology, environmental impact, and economic significance of the most significant resources on the continent. Each title in this series contains color photos, a full-page map, and back matter including: an index, further reading lists for books and internet resources, and a series glossary. Mason Crest's editorial team has placed Key Icons to Look for throughout the books in this series in an effort to encourage library readers to build knowledge, gain awareness, explore possibilities and expand their viewpoints through our content rich non-fiction books. Key Icons are as follows: Words to Understand are shown at the front of each chapter with definitions. These words are then used in the prose throughout that chapter, and are emboldened, so that the reader is able to reference back to the definitions- building their vocabulary and enhancing their reading comprehension. Sidebars are highlighted graphics with content rich material within that allows readers to build knowledge and broaden their perspectives by weaving together additional information to provide realistic and holistic perspectives. Text Dependent Questions are placed at the end of each chapter. They challenge the reader's comprehension of the chapter they have just read, while sending the reader back to the text for more careful attention to the evidence presented there. Research Projects are provided at the end of each chapter as well and provide readers with suggestions for projects that encourage deeper research and analysis. A Series Glossary is included in the back matter contains terminology used throughout the series. Words found here broaden the reader's knowledge and understanding of terms used in this field.