A major United Nations conference on climate change has just opened in the South African city of Durban. Up to 20,000 people from more than 190 nations are expected to attend the two-week conference. At a rally on Sunday night, South African Archbishop Desmond Tutu described climate change as a “huge enemy” that threatens humanity.

South African Archbishop Desmond Tutu: “We are saying this is the last chance. Please, for goodness sake, take the right decision. This is the only world we have. This is the only home we have. If it is destroyed, we all sink.”

Former Irish President Mary Robinson also spoke ahead of the U.N. climate conference. Robinson is founder of the Climate Justice Foundation.

Mary Robinson, founder of the Climate Justice Foundation: “People are suffering because of the impacts of climate, and those who are suffering most are not responsible. So, the rich world has to take its responsibility. We have to have a continuation of Kyoto and a track that leads to a fair, ambitious and binding agreement. And we have to do it here in Durban”

The U.N. Climate Change Conference is opening at a time when South Africa is experiencing a bout of extreme weather. Eight people died in heavy flooding in and near Durban on Sunday. Scores of home were destroyed.