Abstract: A regional climate change consists of many components of the regular (periodic) and irregular forcing from diurnal cycle, annual cycle, inter-annual, decadal, inter-decadal and centennial timescales while every component is phase-lagged in its force. In the twentieth century, most of the global temperature increase belongs to the natural climate variability, and there is a small part of human activity impacts on regional and urban climate changes. Early in this century, a warm fl at was the overlap of several temperature components. On the inter-decadal timescale, regulating global-mean temperature variation is associated with the expansion of monsoon domain.