Another paradigm shift occurred in the 1960s, when geologists accepted plate tectonics. By this time, evidence for the movement of continents and the action of tectonic plates had accumulated and become overwhelmingly convincing. Paradigm shifts demonstrate the strength and vitality of science, showing science to be a process that refines and improves itself through time. Understanding how science works is vital to assessing how scientific interpretations progress through time as information accrues.


This is especially relevant in environmental science—a young field that is changing rapidly as we obtain vast amounts of new information, as human impacts on our planet multiply, and as we gather lessons from the consequences of our actions. Throughout this book you will encounter environmental scientists asking questions, testing hypotheses, conducting experiments, analyzing data, and drawing conclusions about the causes and consequences of environmental change. Environmental scientists, who study the condition of our environment and the nature of our impacts, are addressing the most centrally important issues of our time. Society’s primary challenge today is finding how to live within our planet’s means, such that Earth and its resources can sustain us—and all life—for the future.


This is the challenge of sustainability, a guiding principle of modern environmental science and a concept you will encounter throughout this book. Sustainability means leaving our children and grandchildren a world as rich and full as the world we live in now. It means conserving Earth’s resources so that our descendants may enjoy them as we have. It means developing solutions that work in the long term. Sustainability requires maintaining fully functioning ecological systems, because we cannot sustain human civilization without sustaining the natural systems that nourish it.