Usher, Common, Gwen Stefani and more perform for the free rally..

Usher, Common, Gwen Stefani and more perform for the free rally..

A daylong Earth Day concert had R&B star Usher dancing on crutches in Washington DC to rally thousands for political action to confront climate change and poverty.

Usher, Mary J. Blige, Gwen Stefani, Common, Fall Out Boy and Train all performed during the free Global Citizen 2015 Earth Day rally hosted by and Soledad O'Brien.

After suffering a fracture in his foot, Usher was in a cast but drew big cheers when he got his dance on anyway. He sang his hits, including "Yeah!" and "OMG" and also teamed up with Common to sing the beginning of "Glory," the Oscar-winning song from the movie "Selma."

"To end poverty, it starts, in my opinion, with an education about it," Usher told the crowd. "I want you to go and investigate for yourself so that you can really understand what's going on."

The rally was a joint initiative of the Global Poverty Project and Earth Day Network. It coincides with meetings at the World Bank and International Monetary Fund. "I felt really good that the issues we are addressing here are on the table," Usher told The Associated Press. After his performance, Usher said his passion is expanding education to help end poverty. But the impacts of climate change also have severe impacts on the world's poor, he said.

"Global warming is something that obviously will affect all of us. Clean water and sanitation is something that is very real," he said. "I understand and cannot turn a blind eye to what's going on."

For his part, played host and said the huge turnout shows people are concerned.

"What I hope happens post the concert is that people go out and talk about some of the issues that we were spelling out today," he said. "Talk about solutions, go online, dig deep and hold our leaders accountable for some of the things that they're pledging."

Patrick Stump and Pete Wentz from Fall Out Boy played some of their hits and said they wanted to show their fans everyone has a responsibility to help.

"How do you wake up every day knowing that a lot of these things are within our grasp and just kind of be like oh, ok, whatever," Stump said. "It's frustrating. But I think we're here for the reality that it's hopeful. We can actually do something. We can actually effect change."