Understanding low-frequency (inter-decadal and longer) variability in climate is the key to disentangling human-induced climate change from natural climate variation.
UWA School of Plant Biology staff have researched this using tree rings found in Western Australia's South West.
in Climate Dynamics as following citation:
Cullen L and Grierson PF. (2008). Multi-decadal scale variability in autumn-winter rainfall in south-western Australia since 1655 BP as reconstructed from tree rings of Callitris columellaris. Climate Dynamics DOI 10.1007/s00382-008-0457-8.