"Business as usual cannot be tolerated, for it would condemn millions no, billions billions of children, women, and men around the world to shrinking horizons, and smaller futures," Ban told delegates of 194 nations at the climate change conference.
Kicking off the high-level segment of the climate conference as the two-week talks entered the final four days, he said: "Cancun must represent a breakthrough. The status quo will not do".
"However, I am deeply concerned that our efforts so far have been insufficient...that despite the evidence, and many years of negotiation, we are still not rising to the challenge, he said, adding "Determination must be our watchword."
There are four days left before the meeting ends, which are expected to achieve significant outcomes on issues like reduction of greenhouse gases, providing money to developing countries and saving forests.
These talks come one year after the talks in Denmark, which were supposed to "seal the deal" on a treaty to combat climate change, but instead yielded a political document called the 'Copenhagen Accord,' which left countries deeply divided.
The UN chief acknowledged that solutions would not be found overnight. "I realise you all face political and economic constraints at home," Ban said. "Climate change was not created overnight," he said, adding "It will not be solved overnight either."
Ban, who is attending the fourth climate change conference since becoming Secretary-General, also linked the success of the climate talks with progress on the Millennium Development Goals.
We will not reduce extreme poverty without coming to grips with the increasing intensity and unpredictability of weather trends associated with climate change, he warned.
The UN chief also pointed out that negotiators could not get away with taking decisions on issues where there was already some consensus, but they had to find solutions on the divisive issues like mitigation.
"You can take significant decisions here in Cancun on forests, on adaptation, on technology, and on the creation of a new fund for long-term climate financing," Ban underlined.
"You also need to make progress on mitigation, on anchoring your national commitments, on accountability and transparency, and increasing clarity on the future of the Kyoto Protocol," he added.