Indian summer monsoon during the last two millennia

Abstract

The monsoon is a large-scale feature of the tropical atmospheric circulation, affecting people and economies in the world's most densely populated regions. Future trends due to natural variability and human-induced climate changes are uncertain. Palaeoclimate records can improve our understanding of monsoon dynamics and thereby reduce this uncertainty. Palaeoclimate records have revealed a dramatic decrease in the Asian summer monsoon since the early Holocene maximum 9 ka BP. Here we focus on the last 2 ka, where some records indicate an increasing trend in the summer monsoon. Analysing Globigerina bulloides upwelling records from the Arabian Sea, we find the weakest monsoon occurred 1500 a BP, with an increasing trend towards the present.