The twentieth century, especially in its second half was full of rapid and unprecedented security problems at the Global level. The human impact on the natural environment is so immense, and this caused the environment has become a security problem with Global Dimensions. In today's world, the common interests of countries are increasingly dependent on the collective cooperation of governments and people to protect the earth ecosystem. However, in recent years, these issues have led researchers and policymakers to consider the importance of the environment and environmental policies which are essential to human life. Thus, this book addresses some of the most important environmental issues. More specifically, the role of the United States as a hegemony was analyzed in the convergence and divergence of environmental issues. It was found that the environmental policies of America from 1990 to 2012, has had many ups and downs in the domestic and international level.