US film director James Cameron discusses global environmental policies on Capitol Hill as actress Sigourney Weaver and National Radio host Richard Greene look on. Weaver will return to Washington next week to mark Earth Day, using her celebrity to continue to fight for environmental causes.(AFP/Joyce N. Boghosian)AFP – When Sigourney Weaver wrapped up her role as a feisty environmentalist in James Cameron’s blockbuster movie „Avatar,” the US actress teamed up with Cameron again — to save the Amazon.