The United Nations secretary general, Ban Ki-moon, yesterday urged to consent to a modest deal to rein in climate change without holding out for perfection. After the US president, Barack Obama, and other leaders were not able to work out a new climate treaty at last year's summit in Copenhagen, Ban stressed that Cancún has more modest ambitions: “We don't need final agreement on all the issues, but we do need progress on all the fronts. We cannot let the perfect be the enemy of the good,” Ban said in his address to the opening ceremony of the high-level segment of the COP 16 talks. “Business as usual cannot be tolerated for it would condemn millions – no, billions – of children, women and men around the world to shrinking horizons and smaller futures. Cancún must represent a breakthrough,” he added. The Mexican president, Felipe de Jesús Calderón, warned that time was running out and called on nations to act now. “I urge you, all parties, to make concrete here a balanced packet of agreements that will allow is to advance. A balanced packet of agreements that will allow us to already to take the first actions and steps because we can't wait any longer and time is running out,” claims Calderón.