I’ve noticed your recent thread on the long-term hydrological drought affecting eastern Australia. I’ve whipped off a few charts for you which put this into an historical context based on rainfall data going back to 1900 (some limited earlier data is available).
In terms of eastern Australia, the current meteorological drought started in early 2002 with the emergence of an El Nino event and continues to the present. The first figure below shows essentially drought “deciles” for this period.
As you can see a significant part of SE Queensland has experience its driest 55 month period on record. The data are not spatially dense enough to resolve structures at the catchments scales (though Warwick’s graphs suggest ~5 yearly rainfalls which are lowest on record).
Note that the analysis only shows those areas which are experiencing severe or serious meteorological drought (almost all of eastern Australia has experienced below average rainfall through this period).
Rainfall is only part of the drought story (drought is a function of both water supply and water demand), but it does support the general conclusion that it has been abnormally dry and probably the driest period in “of order” 100 years.
This is just one of three protracted drought periods which Australia is experiencing. Probably the most important from a water management perspective is that which started in early 1997/late 1996 in southern Australia. This is shown in the second figure.
This has seen the Perth, Canberra and Melbourne catchments all experience their lowest (or nearly so) rainfall on record. The third protracted drought event is that which commenced in SW Western Australia in the 1970s and which has been linked to a combination of greenhouse gas increases, ozone depletion and natural variability by the Indian Ocean Climate Initiative (see http://www.ioci.org.au/).
An aspect which is not covered in these analyses is the high temperatures. The third figures shows the mean temperature deciles for the period starting in 2002.
This analysis is based on the post 1950 period only (though temperatures before this time were generally considerably cooler) and uses only the high quality national temperature network discussed at http://www.bom.gov.au/climate/change/reference.shtml .
These stations have minimal or no urban heat island effects. There are a number of papers published on the increasingly warm temperatures which we now experience with droughts (as a result of global warming interacting with climate variability). As you can see almost everywhere has been warmer than average and most of Queensland has experienced its warmest 55 month period on record.