Warning that rising food and oil prices pose a crisis for the world’s poor, Robert B. Zoellick, the president of the World Bank, is calling on President Bush and other leaders convening in Japan next week in an economic summit meeting to make new aid commitments to avert starvation and instability in dozens of countries. “What we are witnessing is not a natural disaster — a silent tsunami or a perfect storm,” Mr. Zoellick said in a letter sent Tuesday evening to the major leaders of the West. “It is a man-made catastrophe, and as such must be fixed by people.”