He said regarding the rain "it may not come".
The implied timeframe was until after the dams were empty.

His opponents had such poor comprehension that they inferred he was saying it WILL NEVER rain again!

Dear loudmouth2,

Perhaps this might help.

http://indifferencegivesyouafright.wordpress.com/2012/08/06/tim-flannery-did-not-say-australias-dams-would-never-fill-again/

Aidan,

One needs to take into account that those who stand against what Tim Flannery has to say about environmental issues have probably never read any of his work such as 'We The Weathermakers'.

I am into environmental sociology these days and Flannery has had a major influence on my thinking.

Flannery urges us to listen to what the scientific community is telling us about climate change.

He challenges the deniers, asking them to define what evidence they need to see that would convince them that anthropogenic global warming is real. He points out they do not have an answer to this question which demonstrates they do not know what they are talking about.

And most importantly, he asks us if we should take a chance that the scientific community is wrong about global warming and climate change because if we are disregard them we will never be able to undo the damage to our planet and human civilisation.

Aidan,

I sincerely apologise. I honestly thought he declared that the dams around Sydney would never fill again.

Just by the way, historically, during a prolonged cold spell, or an Ice Age, or even the Little Ice Ages over the last millenium, not only has it got colder but drier.

Conversely, it seems, during warming periods, such as around 1200-1000 BC, around the time of Christ, and around 800-1200 AD, it seems that rainfall was much more plentiful. i.e. during global warming, perhaps because there is a prolonged, higher level of evaporation over the oceans, there is higher (and perhaps more catastrophic) rainfall.

So, if anything, the current rate of rainfall conforms to the principles of global warming: increases in precipitation. Which isn't necessarily a bad thing, I suppose: over here in SA, we always love when it rains. We might even get more of our rightful share of the Murray-Darling water now.

Joe

Joe,
You are correct that, in general, a warming climate will bring more rain. However there are two reasons why it could have the opposite effect in Australia:
Frstly, it will push the sub tropical high pressure zone further south. This means that southern Australia will get less rain, though the summer rains of northern Australia are likely to extend a bit further south.
Secondly, El Niño events are likely to become both more frequent and more intense. These bring more rain to Chile but less to Australia.

Aidan and pseudo-mouth,

You are both on the right track but how the hydrosphere-atmosphere complex works is still not understood well enough to make accurate predictions.

The El Nino-La Nina system is unpredictable because scientists do not understand how it connects to other things eg the great ocean conveyor belt that circulates water/cold water from the North Sea through the Atlantic and Indian Oceans and into/out of the NE Pacific. If this stops (which it has done) it can throw the northern hemisphere into a cold snap for millennia.

There are plenty of books on this in local libraries. Flannery discusses it and so do writers like Brian Fagan who delves into environmental archaeology just to name a couple.