Weak East Asian summer monsoon during the high atmospheric CO2 middle Pliocene period: Evidenced by red clay record on the Chinese Loess Plateau

Abstract

The mid-Pliocene warm period (MPWP) during 3.3–3.0 Ma has been defined as a potential analog for future climate warming with atmospheric CO₂ concentration higher than the modern level. However, the migration of the East Asian summer monsoon (EASM) rain belt during this period is still controversial, which hinders our understanding of the future environmental changes in China. Two periods, Pleistocene interglacials (with atmospheric CO₂ ∼280 ppmv) and mid-Pliocene (with atmospheric CO₂ ∼450 ppmv) were selected to study the changes of regional humidity and the EASM edge location as high CO₂ forcing. The results show a relatively drier and warmer climate prevails in the area and the edge of the EASM retreated eastward. Our study supports that the edge of the EASM will eastward retreat in the future and the CLP will get drier and warmer with increasing atmospheric CO₂ concentration can be expected.