Too often, our world seems to careen from one crisis to the next: violence in the Middle East, disease in Africa, soaring food and fuel prices around the globe, the threat of climate change. When people are buffeted by one shock after another, it's not uncommon for them to grow pessimistic, to see the world's problems as too intractable to solve. The temptation is to throw up our hands, retreat from the world and tend our own gardens.

Yet from where I sit, on the 38th floor of the United Nations building, the view is rather different. My perspective is of cautious but resolute optimism. Every problem of the world finds its way to the U.N., our global crossroads of politics and diplomacy. But if the problems come together at the U.N., so do the often hidden connections among them—and through those connections, the ways to real solutions. Nowhere is that more apparent than in our approach to climate change. Many of the challenges we face, from poverty to armed conflict, are linked to the effects of global warming. Finding a solution to climate change can bring benefits in other areas. A greener planet will be a more peaceful and prosperous one too.

The U.N. was founded, famously, to "end the scourge of war." We often confuse that with the dispatching of peacekeepers to this or that zone of conflict. I see it differently. The basic building block of peace and security for all peoples is economic and social security, anchored in sustainable development. It is a key to all problems. Why? Because it allows us to address all the great issues—poverty, climate, environment and political stability—as parts of a whole.

Consider Darfur, where I've put considerable diplomatic effort during my first year as Secretary-General. It is, of course, most immediately a challenge of peacemaking and peacekeeping. But Darfur's violence began with the onset of a decades-long drought. Farmers and herders came into conflict over land and water. If this root problem is not addressed—if the challenges of poverty alleviation, environmental stewardship and the control of climate change are not tied together—any solutions we propose in Darfur will at best be a temporary Band-Aid.

More than ever before, solutions must bridge the local and the global. Hunger in Africa will be solved partly by helping farmers get the improved seeds, water pumps and soil nutrients they need for a good harvest. It also requires the traditional U.N. development effort—coupled with a new attention to the environment. Since problems spill across borders, security anywhere depends on sustainable development everywhere.

That brings us back to climate change. No place is immune, neither the arid Sahel of Africa nor the grain-exporting regions of Australia nor the drought-prone Southwest of the U.S. To fight it, the U.N. family, including the Nobel Prize-winning Intergovernmental Panel on Climate Change, has begun tapping into a pool of global resources—scientific and engineering expertise, corporate engagement and civic leadership. We have begun to appreciate more fully how the world's dazzling know-how can solve the seemingly unsolvable when we view our problems through the right perspective.

This year at the U.N., as we link the crucial agendas of poverty reduction and climate change, we must remember that among the best minds are the farmers, doctors and community leaders at the local level who have worked out ingenious solutions to urgent challenges. They tell us that there are indeed pathways, at modest cost, to clean and sustainable energy systems, high-yield agriculture in Africa and improved water management in drought-prone regions of Asia, Africa, the Middle East and the Americas.

This year could mark a watershed at the U.N. We will undertake climate-change negotiations in earnest and accelerate our efforts to achieve the Millennium Development Goals to fight poverty, hunger and disease. As we embark on this great undertaking, we might recall the historic importance of American leadership in this fight. In 1963, President John F. Kennedy told the U.N. General Assembly, "The effort to improve the conditions of man...is not a task for the few. It is the task of all—acting alone, acting in groups, acting in the United Nations. For plague and pestilence, plunder and pollution, the hazards of nature and the hunger of children are the foes of every nation. The earth, the sea and the air are the concern of every nation. And science, technology and education can be the ally of every nation." Let us heed that sound advice.