The international community cannot accept that whole communities are marginalized because of the color of their skin. People of African descent are among those most affected by racism. Too often, they face denial of basic rights such as access to quality health services and education. Such fundamental wrongs have a long and terrible history.

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.

Planet Earth is our shared island, let us join forces to protect it

Climate change, demographics, water, food, energy, global health, women's empowerment - these issues are all intertwined. We cannot look at one strand in isolation. Instead, we must examine how these strands are woven together.

Nuclear terrorism is one of the most serious threats of our time. Even one such attack could inflict mass casualties and create immense suffering and unwanted change in the world forever. This prospect should compel all of us to act to prevent such a catastrophe.

We must follow the wisdom of the Brundtland Report. We must pursue development that meets the needs of the present generation without compromising the ability of future generations to meet their needs.

The longer we delay, the more we will pay.