The Financial Times recently reported on the Australian bushfires, linking them to increases in greenhouse gases. We take another look at the data in the DECR and find Australia is getting wetter not drier:

Scientists say Australia, with its harsh environment, is set to be one of the nations most affected by climate change.

“Continued increases in greenhouse gases will lead to further warming and drier conditions in southern Australia, so the [fire] risks are likely to slightly worsen,” Kevin Hennessy at the Commonwealth Scientific and Industrial Research Centre told Reuters.

Bob Brown, the senator who leads the Greens party, said the bushfires provided stark evidence of what climate change could mean.

“Global warming is predicted to make this sort of event happen 25 per cent, 50 per cent more,” he said. “It’s a sobering reminder of the need for this nation and the whole world to act and put at a priority our need to tackle climate change.”

The Drought Exceptional Circumstances Report, that I have been reviewing in this series, promoted these conclusions. Lets look at another analysis, this time using simple quantile analysis of the data in Table 3. This table contains the average percentage area having exceptionally low rainfall years for selected 40-year periods and the most recent
decade (1998-2007).


1900-1939 1910-1949 1920-1959 1930-1969 1940-1979 1950-1989 1960-1999 1968-2007 1998-2007
Qld 9.5 6.5 5.5 4.1 3.3 3.1 2.7 2.6 4.7
NSW 5.7 6.9 5.7 6.2 5.8 4.3 4.0 3.8 6.4
Vic&Tas 5.3 6.0 4.2 6.1 5.1 5.0 5.3 5.2 8.5
SW 5.2 7.1 7.2 6.9 7.9 5.9 4.9 4.4 3.4
NW* 6.3 5.3 6.5 7.5 6.5 6.1 4.7 3.5 3.3
MDB 6.1 7.2 5.8 6.4 5.7 4.1 3.5 3.5 6.9
SWWA 2.5 4.7 4.1 6.5 8.3 6.1 6.3 8.5 8.9
Australia 6.4 6.4 6.6 6.4 6.3 5.3 4.6 3.5 3.1


Using the function ‘quantile’ in R, we output the percentage areas for each probability in each 40 year period. Then we lookup the probability for each region using the most recent 40 year period 1968-2007.


Quantiles
5% 10% 50% 90% 95%
3.25 4.05 5.85 7.15 7.60



Regions, area and probability drought has increased.
Qld 2.6 <5%
NSW 3.8 <10%
Vic&Tas 5.2 NS
SW 4.4 NS
NW* 3.5 <10%
MDB 3.5 95%
Australia 3.5 <10%


The results show that over the last 40 years, regions Qld, NSW, NW, and MDB have had significantly less area under drought. Only in SWWA has the drought area increased significantly, while Vic&Tas (the region of recent bushfires) and SW have no significant change.

The ‘inconvenient’ results were reported in the DECR text as follows:

Observed trends in exceptionally low rainfall years are highly dependent on the period of analysis due to large variability between decades.

Despite these highly significant DECR results showing Australia getting wetter, not drier, CSIRO scientists continue to report in the media that Australia will get drier.

It only takes two thoughts to realize that wetter conditions can pose greater fire risks due to the greater production of fuel in the wet season, and more dangerous conditions when it drys out. Drier conditions lead to a more open grassland environment in Australia, much like the African Savannah, with cooler grassfires but not the hot forest fires suffered recently in Victoria. You simply cannot look at environmental factors in isolation.

But don’t tell CSIRO, or the next thing we will hear is that greenhouse gases are causing more fires by making it wetter.