Regional character of the “global monsoon”: paleoclimate insights from Northwest Indian lacustrine sediments

Abstract

The concept of a “global monsoon” proposes that the annual insolation cycle and global-scale atmospheric circulation drive and synchronize regional mon-soons. However, model, proxy, and observational studies reveal differences in the regional variability of the summer monsoon and its direct response to solar forcing and glacial boundary conditions. Here, we focus on paleoenvironmental data derived from paleolake sediments in northwest India. These paleolakes straddle a precipitation gra-dient from sub-humid to semi-arid to arid plains and contain a wealth of information about summer monsoon variability at regional scale over the past 10,000 years. The paleolake records provide compelling evidence of significant regional differences in the timing of monsoon responses to orbital forcings; only sub-humid to semi-arid lakes resemble monsoon reconstructions from marine sediment and speleothem archives, while the arid region lakes contain regional hydroclimate histories. Extracting regional trends from the global signature of monsoon variability is necessary for understand-ing the regional impact of future climate warming on the monsoon system and human populations. The paleolakes in northwest India highlight the importance of con-sidering the specific location of archive and signal heterogeneity when interpret-ing monsoon records. Results indicate that detailed records are required from other monsoon regions to improve knowledge of the imprints of the complex monsoon system at regional scales.