The variation of the Asian summer monsoon in warmer climates
For the next century it seems that the major rainfall belts would move northward by about 2040, but unstable. Afterwards, the summer precipitation in North China would increase considerably and stably. Furthermore, this anthropogenically-driven precipitation shift would appear to be consistent with the occurrence of rainfall peak period caused by the natural near-80-yr cycle.
The present study has further shown that the differential increases of the upper-tropospheric temperature over the tropical Indian Ocean (TIO) and Tibetan Plateau (TP) lead to the changed relationship between the South Asian summer monsoon (SASM) intensity and tropospheric thermal contrasts over the SASM regions in a GHG-induced warmer climate. The weakening of the SASM circulation is directly related to the decrease of upper-tropospheric TP-TIO thermal contrast, which in turn is caused by the larger upper-tropospheric warming over the TIO than over the TP. The fact that the SASM weakens as the lower-tropospheric thermal contrast increases in the 21st century implies a smaller role of this thermal contrast in determining the SASM intensity than that suggested by previous studies for the 20th century. Therefore, in the future warm climate, the SASM is likely to have a different trend (weakening) from the Asian summer monsoon (increasing).