  The northwest Australian summer monsoon owes a notable degree of its
interannual variability to interactions with other regional monsoon systems.
Therefore, changes in the nature of these relationships may contribute to
variability in monsoon strength over longer time scales. Previous attempts to
evaluate how proxy records from the Indonesian-Australian monsoon region
correspond to other records from the Indian and East Asian monsoon regions, as
well as to El Ni\~no-related proxy records, have been qualitiative, relying on
`curve-fitting' methods. Here, we seek a quantitative approach for identifying
coupling relationships between paleoclimate proxy records, employing
statistical techniques to compute the interdependence of two paleoclimate time
series. We verify the use of complex networks to identify coupling
relationships between modern climate indices. This method is then extended to a
set of paleoclimate proxy records from the Asian, Australasian and South
American regions spanning the past 9,000 years. The resulting networks
demonstrate the existence of coupling relationships between regional monsoon
systems on millennial time scales, but also highlight the transient nature of
teleconnections during this period. In the context of the northwest Australian
summer monsoon, we recognise a shift in coupling relationships from strong
interhemispheric links with East Asian and ITCZ-related proxy records in the
mid-Holocene to significantly weaker coupling in the later Holocene. Although
the identified links cannot explain the underlying physical processes leading
to coupling between regional monsoon systems, this method provides a step
towards understanding the role that changes in teleconnections play in
millennial- to orbital-scale climate variability.
