@Brian of Buderim: "The second point is that it is very difficult to have a reasoned, calm and rational debate when 2 of the people who are contributing, but not listening, are paid employees of The Heartland Foundation or The Climate Skeptics?"

And who would that be, Brian?

James H Rush is an advisor for the Heartlands Foundation and Anthony Cohen is the secretary of the Climate Skeptics [sic]. James H rush information comes from Google and Anthony Cox comes from this website.
Neither is impartial but makes no reference to their employment in posts on this website.

Brian is what is loosely defined as a Concern Troll:

"A concern troll is a false flag pseudonym created by a user whose actual point of view is opposed to the one that the user claims to hold. The concern troll posts in Web forums devoted to its declared point of view and attempts to sway the group's actions or opinions while claiming to share their goals, but with professed "concerns". The goal is to sow fear, uncertainty and doubt within the group"

Concern Trolls are common, indeed ubiquitous amongst alarmists and are easy to strip of their pseudo moral veneer to reveal their censorious, platitudinous shell.

Brian has contributed nothing to this debate; his sole purpose is to denigrate and besmirch the right of sceptics to express their view and this site for having the temerity to host sceptic views.

Since alarmists, even the best [sic] of them, have nothing except recourse to authority such as the BOM, IPCC etc, which have been discredited they cannot respond once their authoritative source is shown to be deficient.

I'm not sure but I think I saw Brian's name on the credits for Noah as one of the talking rocks; if he wasn't he should have been.

JBowyer, my impression is that Melbourne is drier and warmer now than when I lived there as a child. But because impressions can be wrong, I prefer to look at data. Autumn rainfall in Melbourne has declined by about 80 mm over the past 40 years, which is quite a decline. Spring temperatures have increased by 0.8 C, which is perhaps less concerning.

Because these changes are the same as predicted by models describing the effect of increased CO2 in the atmosphere, one has to consider the possibility that that extra CO2 in the atmosphere is playing a role. We know from research done more than 100 years ago that CO2 absorbs energy in the IR and re-emits it, so increasing CO2 in the atmosphere will warm the atmosphere. We also know from measurements that there is more CO2 in the atmosphere than there has been since agriculture was invented. We also know from measurements that the surface is warmer now than it has been at any time since measurements began and probably since agriculture was invented.

Even if there was to be no more effects of the CO2 currently in the atmosphere, there is a problem in south-eastern Australia. Because spring is warmer, farmers will have to plant their crops earlier to avoid heat stress. However, as autumns are drier, they are getting fewer opportunities to sow the crop. This will inevitably reduce crop yield.

Then we get the scientifically ignorant like cohenite going on about how it there were very hot periods in the late 19th Century and the early 20th Century. Well there were, but they were not as hot as the present temperatures. But if that is some sort of argument around crop production, it is worth remembering that average wheat yields in the first decade of the 20th Century were about 0.5 T/ha as a result of drought (which was also connected to the fact that temperatures were higher)

In response to agro; it is default setting 101 for alarmists to denigrate anyone who disagrees with AGW science; it doesn't matter whether it is Dick Lindzen, John Christy, Roy Spencer, Ross McKitrick or Stewart Franks, all of whom I consider to be the top climate scientists in the world and who are all sceptics. All are wrong.

It is a pathetic tactic.

Agro claims today is climatically exceptional. This is crucial to AGW. But it is NOT TRUE. The MWP was warmer; so was the RWP, the MInoan Warm Period and the Holocene; in terms of the interglacials, this current one is the coolest.

In respect of the Hockeystick McShane and Wyner is the definitive rebuttal of the claim that today is climatically exceptional.

Globally temperature has paused.

Australia seems to be a little hot oasis. Agro has dismissed any concern about the discarding of pre-1910 temp data by BOM. In fact it is a scandal. It is almost certain that the late 19thC was warmer than today in Australia but due to a problematic complaint about a warming bias in the Glaisher stand which was resolved by the Stevenson stand the BOM has literally thrown away decades of temp records.

That single fact along with the rounding controversy when Fahrenheit was converted to Centigrade in 1972 goes along way to explaining why the temp trends in Australia are warmer than the rest of the world.

A real scientist would be concerned about this. Enough questions have been asked about BOM and the CSIRO for an audit but that is being resisted. As I say that is the issue not AGW or the supposed ignorance of sceptics.

Sorry Agro but the AGW people always do retrospective forecasts like Flannerry. Whatever happens it is "Climate change", why not "Global warming"?
I suggest you read Water into Gold written by Ernestine Hill in the 1960's. That detailed much higher temperatures and frosts that destroyed the vine industry crops.
She also detailed when the Murray Darling was a succession of pools for years at a time, enviromental flows anyone?