As I noted on this page in December 2007, the presumptive cause of the world-wide decline in long-term rates was the tectonic shift in the early 1990s by much of the developing world from heavy emphasis on central planning to increasingly dynamic, export-led market competition. The result was a surge in growth in China and a large number of other emerging market economies that led to an excess of global intended savings relative to intended capital investment. That ex ante excess of savings propelled global long-term interest rates progressively lower between early 2000 and 2005.
That decline in long-term interest rates across a wide spectrum of countries statistically explains, and is the most likely major cause of, real-estate capitalization rates that declined and converged across the globe, resulting in the global housing price bubble. (The U.S. price bubble was at, or below, the median according to the International Monetary Fund.) By 2006, long-term interest rates and the home mortgage rates driven by them, for all developed and the main developing economies, had declined to single digits — I believe for the first time ever. I would have thought that the weight of such evidence would lead to wide support for this as a global explanation of the current crisis.
The full article can be found here.