JOHANNESBURG — An anti-apartheid campaigner who on Monday became the head of the environmental group Greenpeace says he will use his activism know-how to spur governments into reversing climate change, stressing that unless dramatic steps are taken "all the world is going to sink."

Kumi Naidoo is the first African to head Greenpeace, said Gerd Leipold, his predecessor.

In an exclusive interview with The Associated Press before he took the helm of the independent global campaigning organization, Naidoo said Greenpeace is committed to dialogue but knows when to deploy headline-grabbing protesters. The activist recently went on a hunger strike to press for solutions to Zimbabwe's political and economic crises and says he learned during the struggle against apartheid the importance of being "strong in our voice and our actions."

Leipold, a German who once headed Greenpeace's nuclear disarmament campaign, said Naidoo's appointment is a watershed for the organization that was founded in the 1970s by Americans campaigning against U.S. nuclear tests and that Naidoo is the first executive director to come from outside the organization.

After battling apartheid as a teen, the South African led global campaigns to end poverty and protect human rights. Naidoo said pursuing commitments to address climate change fits his resume.

Naidoo, 44, has fought for the rights of women and children, among the most vulnerable when droughts bring hunger or floods disrupt livelihoods. He has pushed to strengthen international cooperation and ensure the concerns of poor countries are heard when rich nations plan the future.

Greenpeace will be present when negotiators sit down next month in Copenhagen to try to draft an agreement to cut greenhouse gas emissions blamed for global warming.

"We either get it right and all of humanity comes out on the other side with a new world," Naidoo said in the interview Thursday. "Or we get it wrong and all the world is going to sink."

But world leaders said Sunday it is unrealistic to expect an international, legally binding agreement to emerge from Copenhagen. Instead, the goal is a political framework, with a fully binding legal agreement left to a second meeting next year in Mexico City.

"Anything short of a binding treaty in Copenhagen must be read as a failure of leadership on the part of the political class," Naidoo told a news conference on Monday. "We can't change the science. The science is clear. We have to change the politics. If we can't change the politics, then we have to put our energies into changing the politicians."