The Australian Climate Commission pdf paper – “THE CRITICAL DECADE Queensland climate impacts and opportunities” has a Figure 3 shown below.
Which shows how Queensland has become drier in the 1970-2011 period.
But taking another view of Queensland rain data – this BoM chart of Qld annual rain anomalies 1900 to 2011 shows the cyclic and erratic nature of Queensland rain. This chart also shows that the large brown areas in Qld on the Climate Commission Figure 3 for 1970-2011 are entirely due to the careful selection by the Climate Commission of 1970 as a starting point – the decade 1970-79 having the highest values for the 11 year average rain for over a century.
For another view of recent Qld rain checkout that map of Australian rain deciles for the past 36 months.
No shortage of rain anywhere in Queensland since 1 Nov 2009. So it pays to look at a variety of data sources to better understand the numbers behind what you are being told by GreenLabor and their propaganda organizations.
I’m finding this confusing.
Is the colour map showing the trend across the indicated period rather than mean rainfall? (given that rainfall can’t be -neg, makes a lot more sense)
If that’s true then obviously it’s the first one — 1900-2011 — which is meaningful from a global warming perspective i.e. the trend from the start of the century to now. (or dumbing further down for the benefit of any Climate Commission readers – is there more rain or less rain after a century of global warming?)
Then obviously yes, they’ve thrown in the 1970-2011 map just so they can show one with some scary red splattered about on it.
But then it could be seen as more malicious than that. Putting the scary red one with end of century dates after another green one with start of century dates might very well deceive the less astute reader into thinking that we started off green at the start of the century and ended red at the end of the century. Given the otherwise nonsensical use of the 1970-2011 period I wouldn’t put it past them that they had exactly that in mind with this presentation.
Warwick – thanks for posting this up and flagging it to me separately. Good to see that my deduction about high rainfall in the 1970s was correct.
DaveA – yes, you’re right, the colour maps show the trend over the indicated period, in millimetres of annual rainfall, per decade. So the nasty dark brown in the second map gouging into the central and southern Queensland coast, shows a 40 or 50 millimetre per decade fall in annual rain over the period 1970 to 2011, in other words, a 200mm per year fall over the whole period.
Now that’s a lot, but remember it’s only one area of Queensland. Warwick’s bar chart shows that, for the state as a whole, rain peaked in the 1970s at about 100 mm more per year than it is now. That is consistent with the 1970-2011 Queensland map – a few dark brown bits with 200mm or even more falls, quite a lot of lighter brown, indicating falls 50, 100mms or more in annual rainfall over the 41 years, and a few areas with some modest rises in rainfall. So, on average, about 100mm drop from the 1970s plateau.
I suspect you are right in the rest of what you say too. The century-long trend is far more relevant for climate change assessment, but the Commissioners have chucked in a shorter trend to give the impression that rainfall is somehow lower in recent years than usual. That is not the case. It was just that the 1970s were almost continuously wet. Over the century there is no drying trend, if anything the trend is slightly up, though largely still because of that string of wet years in the 70s.
Given the misleading alarmism of their Figure 2, which Warwick discussed earlier, I can also only agree with you that: Putting the scary red one with end of century dates after another green one with start of century dates might very well deceive the less astute reader into thinking that we started off green at the start of the century and ended red at the end of the century. Given the otherwise nonsensical use of the 1970-2011 period I wouldn’t put it past them that they had exactly that in mind with this presentation.
The only other explanation is scientific illiteracy. That is, they don’t know that shorter trends are less reliable, and more dependent on the start and end points. In this case, the 70s were generally wet, so the trend from then to now is sharply down in some places – although up in others. Overall there is no meaningful trend at all, and no point in making any sort of fuss.
But the pathetic aspect of these maps to me is that, once again, the Commissioners have managed to bungle the simplest possible operation of copying something from a BoM site. Here the task was incredibly easy – literally just copy and paste. But once again they have managed to foul it up – no units for the scale, or explanation of what the maps show. The originals are here and clearly state, for example: “Trend in Annual Total Rainfall 1970-2011 (mm/10yrs)”. They must have very carefully cut around that title to get Tasmania into their screen capture while meticulously excluding the title that explained what the map actually showed.
This is not the place to get into the dismal content of the actual text of this and other State reports of the Commission, which are chock-a-block with gushing encomia for solar and wind power, green buildings, bike paths and other fads, without the slightest hint of any cost-benefit analysis. But like Warwick I say, disband this wasteful Commission now!