You are here to step into the shoes of UN ambassadors - to draft resolutions, to plot strategy, to negotiate with your allies as well as your adversaries. Your goal may be to resolve a conflict, to cope with a natural disaster or to bring nations together on an issue like climate change. You may be playing a role, but you are also preparing for life. You are acting as global citizens.

The power of the leader is given to him by the people, so he has a duty to engage and listen more attentively and carefully to the aspirations of the people.

Our world is one of terrible contradictions. Plenty of food, but one billion people go hungry. Lavish lifestyles for a few, but poverty for too many others. Huge advances in medicine while mothers die every day in childbirth, and children die every day from drinking dirty water. Billions spent on weapons to kill people instead of keeping them safe.

Women must be full partners in development, so they can lift themselves and their communities out of poverty.

Climate change is destroying our path to sustainability. Ours is a world of looming challenges and increasingly limited resources. Sustainable development offers the best chance to adjust our course.

Many say our world is at a tipping point. If we do not act together, if we do not act responsibly, if we do not act now, we risk slipping into a cycle of poverty, degradation, and despair.

Climate change...is, simply, the greatest collective challenge we face as a human family.