You have to work and think about how we can make this world a better place for all. This is what I'd really like to ask our young leaders. We will try as leaders of today to minimise the problems which we will hand over to you. But it is to you. You have to take ownership and leadership of tomorrow. For that to be possible, you have to strengthen your capacity and widen your vision as a global citizen.

The current model is global suicide. We need a revolution. Revolutionary thinking. Revolutionary action. Natural resources are becoming more and more scarce.

One of the main lessons I have learned during my five years as Secretary-General is that broad partnerships are the key to solving broad challenges. When governments, the United Nations, businesses, philanthropies and civil society work hand-in-hand, we can achieve great things.

I call for the need of world leaders to address climate change and reduce the increasing risk of disasters- and world leaders must include mayors, townships and community leaders.

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.

We have all heard of the web of life. The way we live threatens to trap us in a web of death.

We must turn the greatest collective challenge facing humankind today – climate change – into the greatest opportunity for common progress towards a sustainable future.