By Keith Harper, Rob Roy Smith and Claire Newman (March 26, 2018, 5:13 PM EDT) -- Native American tribes in the United States have long been leaders in environmental protection and since the U.S. pulled out of the Paris Climate Agreement in June 2017, they have stepped up efforts at the local, state, national and international levels to combat climate change. As inherently land-based communities, tribes are disproportionately affected by the impacts of climate change and are less likely to relocate from the places that have been their homeland since time immemorial. Action on climate change also presents new opportunities. Tribes are uniquely positioned to employ their abundant traditional knowledge of the natural environment to guide comprehensive approaches to climate adaptation and mitigation. In addition to these issues, this article discusses new doors that are opening for tribes willing to exercise their sovereignty to push for bold action at the local, state, national and international levels....