Why America's Currency Is the World's Problem

The ailing US economy seems to be driving the exchange rate of the dollar inexorably downward, with serious consequences for the global economy. Politicians and central bankers are looking on helplessly as the economic outlook worsens by the day and European companies rack up huge losses.

It costs about four cents to produce a one-dollar bill -- a pittance, compared to the greenback's influence on the world's economy.

The exchange rate of the dollar can boost the fortunes of companies and entire economies -- or plunge them into crisis. Its rate against the euro fluctuates by a few hundredths of a cent each day. But in the past five years that fluctuation has more often than not taken the US currency on a downward trajectory, causing consternation -- and now despair -- among people around the world.