Darwin doesn’t have a water shortage. Quite the opposite in some ways. I think I’m just about ready for the wet season to end. Travelling to Sydney at Christmas was quite a strange experience in that context. There people can’t even hose down their cars and can only water their gardens with a hand-held hose (which must mean the garden will go brown and die unless there’s fairly frequent rain).
In fact Sydney’s gardens are looking quite healthy, because they have been getting pretty frequent rain. So why are there ongoing draconian water restrictions? Strangely, Sydneysiders mostly don’t seem to ask this obvious question, at least not very insistently. I suspect they’ve been conned by Bob Carr’s calculated pontificating about global warming, and have assumed erroneously that it explains Sydney’s “water shortage”. In fact, it’s likely that global warming does provide part of the reason, although very much a subsidiary one. As this article by Barrie Pittock explains:
Australian average temperatures have risen by 0.7 ºC over the last century, and the warming trend appears to have emerged from the background of natural climate variability in the second half of the 20th century. Rainfall has increased over the last 50 years over northwestern Australia, but decreased in the southwest of Western Australia, and in much of south-eastern Australia, especially in winter. The changes are consistent with an observed increase in mean sea level pressure over much of southern Australia in winter. Effects on runoff are potentially serious as evidenced by a 50% drop in water supply to the reservoirs supplying Perth since the 1970s and near-record low water levels in storages in much of south-eastern Australia in 2002-03 due to low rainfall and high temperatures in the south-east since 1996.
Attribution of the rainfall changes is under lively discussion within the scientific community. In the case of the south-west of Western Australia, a combination of natural variability and a trend due to the enhanced greenhouse effect is considered to be the likely cause, although recent papers suggest that stratospheric ozone depletion may also be causing a southward shift of the westerlies and associated rainfall systems. Northern Hemisphere aerosol effects may also have played a part via changes to atmospheric dynamics, but as aerosol lifetimes in the atmosphere are short and precursor sulfur emissions are being curtailed, this effect is probably of diminishing importance. If rainfall decreases are due to anthropogenic effects they may well continue, necessitating “informed adaptation” to a reduced water supply.
It is at least as difficult, with the current state of knowledge, to attribute changes in Australian ecosystems to climate change, as other local causes are possible in many cases. However, a number of observed changes in vegetation, wetlands, terrestrial vertebrates, marine birds and coral reefs are consistent with regional warming trends. …
The Australian region spans the tropics to mid-latitudes and has varied climates and ecosystems, including deserts, rangelands, rainforests, coral reefs and alpine areas. The climate is strongly influenced by the surrounding oceans. The ENSO phenomenon leads to alternations between floods and prolonged droughts, especially in eastern Australia. The region is therefore sensitive to the uncertain but possible change toward a more El Ni±o-like mean state suggested by the TAR.
There are lots of qualifiers and unknowns in there, but it seems likely that global warming is a factor. But undeniably a far more significant reason for Sydney’s “water shortage” is population increase and the failure of successive NSW state governments to plan for it and build adequate new dam infrastructure. When the massive 682,830 megalitre Warragamba Dam was completed in 1960, Sydney’s population was a bit over 2 million. Since then, Sydney’s population has doubled to over 4.3 million while only a miserable 60,000 megalitres has been added to the city’s total catchment capacity with the completion of the Shoalhaven scheme (Tallowa, Fitzroy and Wingecaribee dams) in the late 1970s.
Moreover, a previously-planned expansion of the Shoalhaven scheme would certainly have avoided any water shortages at all. The existing Shoalhaven scheme dams have all been full throughout the current “water shortage” and indeed Tallowa has overflowed its dam wall on an average of 162 days each year. Unlike Warragamba, the Shoalhaven valley isn’t in a “rain shadow”. As SJ, a frequent commenter at John Quiggin’s blog, explains:
I should expand on this a bit vis-a-vis Sydney. Water usage in Sydney is something like 630 GL/pa, and the average inflows into the catchemnts are about 2,100 GL/pa.
600 GL/pa of that inflow goes into the main storage system: Warragamba, Nepean, Avon, Cataract, Cordeaux, Woronora Dams, having a total storage capacity of about 2,300 GL, or about 4 years of inflow.
The other 1,500 GL/pa of inflow goes into Tallowa Dam, which can store only 90 GL, or about 3 weeks of inflow.
The now-shelved plans for expansion of the Shoalhaven scheme involved raising the height of the Tallowa dam wall, and a new and much larger dam further up the Shoalhaven at Welcome Reef. It was both feasible and affordable in an engineering sense, and had no significant adverse environmental effects that the greenies were able to discover, but they managed to scuttle the plans anyway with help from local Coalition-voting NIMBYs. I wonder what Sydney’s voters would think of the Carr/Dilemma government if they actually realised that they were enduring utterly unnecessary water restrictions in order to avoid possible minor discomfort to a few long-nosed potoroos?
Incidentally, although the greenies assert that the potoroo and a few other birds and animals found around the Welcome Reef area are “rare and threatened”, none of them are actually listed as endangered or threatened by the NSW Parks and Wildlife Service (although some are theatened in particular local habitats).
Given the lack of environmental justification, it’s a bit difficult to see why Carr ran up the white flag on the Shoalhaven scheme and declared the area previously set aside for Welcome Reef dam as a national park. The political justification is also a bit obscure given that all the surrounding state electorates are held by the Coalition.
Carr’s successor Morris Dilemma doesn’t appear to have any coherent water policy whatsoever. He recently abandoned a hare-brained Carr promise to build a hugely expensive, greenhouse gas-producing desalination plant that would have done little to alleviate the water shortage anyway, but has put nothing in its place other than an assertion that “newly-discovered” local aquifers have relieved the situation and avoided the need to do anything at all!!
But Warragamba Dam is still only about 44% full, Sydney’s population continues to grow (most estimates suggest a probable population around 6 million by 2050), and the best scientific estimates on global warming indicate that evaporation rates in south-eastern Australia will continue to rise with average temperatures, even if there aren’t any further reductions in average rainfall. So why isn’t the NSW government taking any positive action apart from water restrictions, a meazly subsidy for rainwater tanks and a free water saving kit including low flow shower heads and the like? No sign of any tax incentives for more extensive private use of “grey” water, which could certainly result in significant further cuts in per capita water consumption, and certainly no sign of any serious plans to build new dams. Why?
I can only postulate that Carr had a grand strategy of pandering to the green vote by making frequent empty prognostications about global warming and turning biggish slabs of wilderness into national parks, while simultaneously keeping the corporate sector onside by continuing to build greenhouse gas-emitting power stations, deliberately neglecting public transport and promoting privately-funded tunnels and motorways whose main effect has been to boost road traffic volumes and therefore create yet more greenhouse gases from exhaust emissions. While Bob Carr’s political smarts were undeniable, in policy terms the Carr/Dilemma regime may well be the most incompetent government New South Wales has seen since Bob Askin. Of course, Askin was corrupt as well as incompetent. But I wonder what word adequately describes a Premier who calculatedly runs down the public transport system and agrees to close public roads in order to advantage the private developers of toll tunnels and motorways, and then accepts a lucrative consultancy from the principal beneficiary of those policies as soon as he retires?
Sadly, the NSW Coalition is highly unlikely to do anything effective about Sydney’s water shortage either. Bad governments exist in part because of even worse oppositions, and New South Wales is currently very poorly served by both major parties. As observed earlier, all the state seats surrounding Tallowa and Welcome Reef are held by the Coalition. Opposition activity on the issue consists of running a local scare campaign to convince Southern Highlanders that Dilemma actually has a secret dam-building plan that he’s hiding until after the next election. I certainly hope so, but Dilemma strikes me as more an ineffectual bumbler than a decisive Machiavellian plotter.