Early last year, while "Avatar" was still dominating the box office, Sigourney Weaver joined director James Cameron and some other castmates visiting indigenous tribes in the Amazon. Their purpose was to see firsthand the effects that the proposed Belo Monte Dam Complex would have on the region and its people.

By joining in the protest of the project, which would flood 668 square kilometers and displace more than 20,000 people, Weaver and Co. thought they could bring some additional worldwide attention to the project — and convince the Brazilian government to scrap it. Unfortunately, months later, the dam is still moving ahead, so a new media blitz has been created to fight back.

First up is Weaver's narration for a new Google Earth animation on the Belo Monte, with a goal of informing local people about the impacts of dam and other hydroelectric projects: "Even for people who live along the Xingu River itself, the impacts of damming the river are difficult to understand," said Antonia Melo, a leader and spokesperson of the Xingu River Forever Alive Movement. "This animation can help the local population visualize the potential damage caused by Belo Monte, and can encourage them to take action."

The 10-minute video animates the flooding associated with the dam, the impact on the region's spectacular biodiversity, and maps out more than 60 dams planned for the Brazilian Amazon over the next two decades.

In "Message from Pandora", James Cameron takes the documentary route with a short film based on his travels to Brazil — and firsthand interviews with indigenous people impacted by the project. It will be included in the special-edition box set of "Avatar" due to be released in November.

“Here were people whose lives were going to be altered irrevocably, whose communities were going to be destroyed, literally put under water, or affected negatively as the river’s flow would change,” Cameron said in a statement. “For these people, it’s the end of their world, as they know it.”

Check out Weaver's presentation and Cameron's trailer below:

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Sigourney Weaver, James Cameron fight Amazon dam project
'Avatar' star and director launch new media blitz to convince Brazilian government to drop plans for controversial hydroelectric project.