Greenpeace activists protested Friday in Barcelona, Spain, against the role the United States has played in producing greenhouse gases and urged world leaders to attach importance to the climate change.

The protests were mounted as the last negotiating session before the UN climate change conference in Copenhagen in December was being held in Barcelona.

The activists climbed to the city's trademark, the statue of Christopher Columbus, and hugged a banner with the slogan "Climate Chaos, who is culpable?".

Director General of Greenpeace in Spain Juan Lopez de Uralde said the organization had pointed to the United States as it was the main culprit for the climate catastrophe awaiting the humankind.

Greenpeace, an independent global campaigning organization that acts to protect environment, also criticized Spanish Prime Minister Jose Luis Zapatero for having not attended the talks.

Uralde lamented that Zapatero had not used the Barcelona conference to show a clear will to reach a climate agreement. "It seems he hardly cares that the meeting is in our country."

Meanwhile, Greenpeace published a document, The Guide to the Political Climate, stressing the contradiction between the words of world leaders and their deeds to prevent climate change.

"The lives of hundreds of millions of people are in danger, along with the destiny of innumerable species. We know what the problems are and we also know what agreement needs to be reached," said Jose Luis Garcia Ortega, member of the Greenpeace delegation in Barcelona.