Perth’s Big Dry  

WA Today reports that Perth looks like running out of dam water this summer courtesy of climate change induced declines in rainfall and deforestation, forcing the city to rely on water from aquifers and from the new-ish desalination plants - Perth’s Dry Dams.

Perth's drinking water supplies from dams will run out by the end of next summer even with decent rainfall, according to predictions by the Centre for Water Research. By then, Perth and the South-West would become solely reliant on water supplied from the already stressed Gnangara Mound aquifer and the Kwinana desalination plant, director Jorg Imberger said.

Even using an optimistic calculation that 35 gigalitres (35 billion litres) of rainwater would flow into the city's dams - far greater than the 13 gigalitres last year - the dams would run dry. "(Even) given recycled water, less water use, pumping the surface aquifer at Gnangara Mound a little bit more and hoping for rain, we'll basically have no water left at the end of summer 2012," Professor Imberger said.

The comments confer with the national Climate Commissioner's first report released yesterday, which warns that water availability will be at great risk before the end of the century due to changing rainfall patterns.

WA's South-West region was already "drying out" and all projections showed no improvement, the report by Professor Will Steffen said. "Rainfall is the main driver of run-off, which is the direct link to water availability," the report says. "Hydrological modelling indicates that water availability will likely decline in south-west Western Australia."

Perth's dam capacity is already below 25 per cent and only 10 per cent of that is drinkable.
WA Water Commission figures show the average amount of rainfall flowing into the dams has dramatically declined since 1974:

* 1911 - 1974 - 338 gigalitres
* 1974 - 2000 - 117 gigalitres
* 2001 - 2005 - 92.4 gigalitres
* 2006 - 2010 - 57.7 gigalitres



"It's raining less but the reduction into reservoirs has reduced even more because the vegetation is sucking up the rest (due to deforestation)," Professor Imberger said. "Between 30-40 per cent of that reduction is due to climate change. The remainder is down to land clearing - trees are not (there to) recycle water the way they used to be."

But a Water Corporation spokesman said it was too early too predict how much water would be left in the dams by early next year. He said over the past 10 years the dams had averaged 100 billion litres of water per year, although last year only 13 billion litres flowed.

Rainfall flows into the dams had been getting later and later each year but it already started this year. According to the Bureau of Meteorology, the Perth metropolitan area recorded only 59 per cent of its average annual rainfall last year. A record hot summer brought no relief and so far this year, less than 50 millimetres of rain has fallen in Perth.

Professor Imberger said the state government's only option to avoid running out of drinking water was to immediately bring other sources online. That included expanding use of the Yarragadee aquifer in the South-West, doubling capacity of the second desalination plant at Binningup - due to come online by the end of the year to provide 45 gigalitres of water - to 100 gigalitres, and improving water recycling.

The SMH has an article on the Climate Commission report referred to above - Cutting fossil fuel production the green key.

Speaking at the launch of the Commission's report, The Critical Decade, into climate science, the report's author, Will Steffen said any climate change policy needs to quickly drive investment away from fossil fuels to ensure long-term emissions reductions. The Commission chief, Tim Flannery, said while efforts should be taken to store carbon in the landscape, it wouldn't prepare the whole economy for the necessary cuts to greenhouse gases. ...

While Professor Steffen did not comment directly on the Coalition's direct action policy, he said if storing carbon in soils is used as the ''the only methodology, as the primary one, and you allow emissions from fossil fuel emissions to go up, you won't solve the climate change problem, the science is clear on that. There is a very good case to be made for getting carbon back into the land, but if that is all you do, or you use that to delay action on fossil fuel emissions, you will have gone backwards a long way,'' he said....

The debate on soil carbon came as the top climate change official confirmed that the government's promise to use more than 50 per cent of the revenue generated by a carbon price for household compensation included measures to reduce the impact of petrol price rises.

The Australian reports the greens are calling for a ban on new coal mines while the details of the carbon tax are sorted out - Greens call for ban on new coal mines as they negotiate with Labor over carbon price.

GREENS deputy leader Christine Milne has called for a ban on new coal mines, amid signs of a growing gulf between the minor party and Labor as they try to reach an agreement on pricing carbon. Welcoming a Climate Commission report calling for urgent emissions cuts, Senator Milne said her party was pushing for the highest possible carbon price it could achieve in its talks with the government.

She attacked the burgeoning coal seam gas industry as a “disaster”, and said coal industry expansion should end. “(Coal seam gas) is not an industry we should be beginning at a time when we need to be getting away from investment in fossil fuels,” she said. “In terms of coal mines, the Greens have said very clearly no new coal mines, no extension of existing coal mines. Let's invest in renewables.”