Young joined the group of ranchers, farmers and indigenous leaders who have been camped out on the National Mall for nearly a week protesting the pipeline.
Asked what had motivated him to join the protest, Young said: "The world, the basis of everything."
Young was quick to point out that each gallon of gasoline wrung from the Canadian tar-sands adds another four pounds of CO2 to the atmosphere. "The oil being taken from the ground in Canada is three times uglier, three times as damaging as the stuff from Saudi Arabia," Young added. "It's time to turn the corner on this abuse."
Young said he and the group of ranchers, farmers and Native Americans -- known collectively as the Cowboy and Indian Alliance -- hope the protest sends a strong message to President Obama and the American people, a message that the environment needs to be protected.
"Maybe we can make a statement for world history," Young said.
The rock icon and the Cowboy and Indian Alliance -- including leaders from Native American tribes like the Dene, Cree and Metis Peoples -- were joined by protesters from across the United States, as well as actress and avid environmentalist Daryl Hannah.
Rich Rusk, who hails from Athens, Georgia and wandered the protest grounds armed with his fly rod, said he came on behalf of fly fishermen. Rusk serves as the secretary for the Georgia Climate Change Coalition, which sent a delegation to join the chorus of environmental activists.
"We see the impacts of pollution and climate change on our fish," Rusk said. As a group, fly fisherman come from a diverse range of political perspectives, Rusk acknowledged. "But we'll stay together on climate issues like this."
The Saturday protest featured music and speeches followed by a procession around the Capitol. The week-long encampment is expected to end Sunday with a traditional ceremony led by Tribal elders.