Abstract
Global environmental challenges in 21st century are more threatening than traditional national security threats on the world because it has had effects globally and victims are completely in a state of natural disaster. The only things which can be secured from these threats are the precautionary measures before these threats occur. The excessive number of natural disaster particularly in past ten year horrified the world and transfers their attention more towards the environmental changes. The geographical location of American continent and growing military activities and WMDs testing of USA needed to focus on the rapid environmental changes around the world especially after the 20th century, because these changes affected the entire world in the shape of excessive rains, tornados and cyclones. The paper analyzes the various challenges of environment for North America particularly for United States by its own actions and in general to the world faces today, as well as measures that have been taken by entire world and United States and their future impact.