This wet season (May to August or MJJA) in southwestern Australia has been certainly the driest since before 1885. Rainfall has, as you can see here, been as much as 47 percent below the pre-anthropogenic global warming average, which I will take as the average up to and including 1967. (Though exact data from 1885 to 1899 are not available, sufficient rainfall records for southwestern Australia do exist to show that including these years makes negligible difference.) What is alarming is that of the nineteen wettest wet seasons in southwestern Australia, not one has occurred in the past twenty-two years and only one in the past thirty-six. In fact, not one May to August period since 1989 has had a southwestern Australian rainfall reaching the pre-global warming average.
If we accept Tim Flannery’s view that major climate shifts began in 1976, then we can take a “pre-global warming” average May to August rainfall over southwestern Australia up to and including 1974. Under such a scenario, 1996 is slightly above the pre-global warming average by five millimetres or one percent, but every other of the last twenty-two years has had below normal wet season rainfall. More than that, six of the nineteen driest wet seasons in southwestern Australia since 1885 have occurred in the past decade alone (1894 has no exact average available, but was certainly as dry as the “nineteen driest” wet seasons listed here).
The key point is that everybody concerned with global warming should see that these changes are in fact less than what can be expected with my estimated poleward expansion of the Hadley circulation of around ten degrees since 1967 (data unfortunately only exist from 1979, by when southwestern Australia’s climate was already severely affected by anthropogenic greenhouse gases). On this basis, Perth is climatically today well within the tropical belt and right amidst the descending air of the Hadley circulation, whilst the ascending, rain-bearing air is well south even of Northcliffe, before 1968 the wettest town in Western Australia. The rainfall and temperature data for the winter of 2010 suggest that what we are seeing, as we did in the winter of 1998, the development of a “tropical easterly jet” over Australia that drives moisture in from north of the edge of the Hadley circulation to large areas on inland Australia that have historically been rainless during this time of year. Tropical Australia this drought season has had a remarkable number of rain events, so that parts of the historically arid interior have had totals as high as that of Perth! The observed extremely high sunshine and frosts over southwestern Australia result from the region under this new climate pattern being the centre of a high pressure system north of which moist air is fed into the rest of the continent.
Even should the arid zone become less arid, it will not become more productive because the soils will become like those of tropical Australia: ever since agriculture began the most intransigent obstacle in the world to its spread. What is worse is that at the present rate even the historically humid karri-forest regions will quite soon under present rates of CO2 concentration increase be too dry for the extraordinarily diverse flora and wildflowers of southwestern Australia. Already decimated by land clearing for cheap food, the unique kwongan now faces anthropogenic global warming as its greatest threat.
Saving the kwongan is something that would under present rates of climate change be an amazing feat. Green Left Weekly suggest that the preservation of the Mediterranean climate to which it is adapted would require an actual reduction in CO2 concentrations, a view supported by paleoclimate data.
To achieve such an actual reduction would require the masses of Australians:
- to be more aware of how much the climate is drying out, via using only pre-anthropogenic global warming (say pre-1968 or pre-1975) rainfall averages
- to demand:
- a restoration of the mining tax
- constitutional laws to require governments to spend all transport funding on railways or road demolition
- lowering road capacity to pre-1974 levels, when public transport paid its way profitably with zero subsidies
- to campaign for ultimate the abolition of private motorised transport from Australia, a step that with climate and biodiversity data known in 1980 could have been demanded then.
- The Democratic Socialist Party suggest that if the profits of mining and car companies were redirected into mass transit, abolition of private road vehicles could be achieved without any mobility loss