The published graph clearly shows a very strong inverse match between rises and falls in snow at Law Dome and rainfall in south-west Western Australia for the past 100 years.
Up until 1970.
At which point, Dr van Ommen observes, there is a breaking of this close coupling.
According to Dr van Ommen, "Since the late 1960s there has been a 15-20% decline in winter rainfall in south-west Western Australia, and at the same time there has been a 10% increase in snowfall at Law Dome."
Van Ommen continues, "In the past three decades the strength of persistent high and low pressure systems off southern Australia have increased, directing more warm, moist air south towards the coast of Antarctica and dry, cold air north in winter."
He then concludes that, "This does not appear to be in the range of natural variability: we can see from the ice core that an event like the increased snowfall at Law Dome would only come along once every 38,000 years without some change in climate patterns and, given the connection we see with Western Australia, it would suggest that the drought is also not a natural event."
Extrapolating from this, Dr van Ommen concludes that human-induced climate change is the most likely cause, the observed changes being derived from either reductions in ozone or increased levels of atmospheric carbon dioxide.
Clearly this is just one small study, but it certainly adds to the weight of evidence in support of human-induced climate change.