Archive for the ‘floods’ Category

Is Australia Getting Harder To Live In?

March 23, 2022

Update: see link below kindly supplied by Big M

According to Scomo it is.

And are natural disasters becoming worse and more frequent?

If you listen to or look at commentary in the mass media and social media, largely fuelled by politicians and journalists with no contact with nature and no life experience, you might think so.

The Conversation says:

It’s too soon to say whether the current floods are directly linked to climate change. But we know such disasters are becoming more frequent and severe as the climate heats up.

Time for a reality check.

Flood and fire and famine are the three great normals of Australia, as so well expressed by Dorothea McKellar in My Country, and we in the north also have cyclones.   

First, floods.  Brisbane was hit hard by floods last month.  Figure 1 is from a previous post, showing historic floods in the Brisbane River with the 2022 flood inserted.  No cause for alarm there.

Figure 1: Historic Brisbane Flood heights 

What about fatalities?  Figure 2 shows the 2022 floods compared with some historic floods from all over Australia.  Fatalities are totalled if several floods occurred in one year.

Figure 2:  Death tolls of flooding events

Are flood disasters getting deadlier? No.

Fatalities and housing damage are the result of people living in flood prone areas- or from being trapped in vehicles in rising waters.   After the 1916 flood, the people of Clermont in Queensland moved their town to higher ground- without any government assistance.  This photo from Bonzle shows the Commercial Hotel being moved on log rollers by a steam traction engine.  The Commercial is still standing- I’ve had a few coldies there.

Figure 3: Moving the Commercial Hotel to higher ground

And no one asked where Billy Hughes was.

What about fires?

Figure 4 shows the area of land burnt by bushfires by notable fires across Australia.  I have marked some fires that are fairly well known- but does anyone mention the fires of the 1960s and 1970s?  These were in largely savannah country of WA, Queensland, and the NT.

Figure 4:  Area Burnt by Bushfires

Figure 5 shows fatalities due to bushfires.

Figure 5:  Bushfire Fatalities 1920-2020

Despite the terrible 2009 fires, fatalities due to bushfires in the last 100 years have been trending down.  Lessons must be learned from these tragic events.  We should remember that fire is part of the Australian bush.  Many fatalities occur where housing is surrounded by bushland, with poor escape routes.

The downtrend in fire fatalities is even more apparent when you consider Australia’s population has grown enormously since 1920.  The following plot shows how the risk of death by bushfire has changed.

Figure 6:  Bushfire Fatalities per 1,000 people 1920-2020

No, by no measure are bushfires getting worse, or making Australia harder to live in.

Droughts are also in decline across most of Australia.  The following plots use BOM data.

Figure 7:  Percentage of Land in Severe Drought (lowest 10% of rainfall)

Even though 2019 was an extremely dry year, over 120 years the area of land in drought is decreasing at the rate of 0.23% per decade.

The only areas where drought has increased are Southwestern Western Australia, Victoria, and southern South Australia. 

In southern Australia as a whole, there is no trend in droughts, even with the 2018-2019 drought.

Decadal averages are an excellent way of showing long term patterns.  In southern Australia the worst period of long lasting dry years was the 60 years from 1920 to 1980.

Figure 8:  Percentage of Land in Severe Drought- Decadal Averages Southern Australia

But are dry periods getting drier, and wet periods wetter?  And are dry areas getting drier, and wet areas wetter?  Here are long term rainfall records for Sydney, Cairns (very wet) and Alice Springs (very dry), and Adelaide (drying trend) again with decadal means.  Values are anomalies from months of overlap of weather stations, in millimetres of rain.

Figure 9:  Decadal Mean Rainfall- Sydney

The three major droughts stand out, as does the major reset of the 1950s.  Note the decreasing values to the 1940s, and again from the 1960s.  There is no indication of wet periods getting wetter and dry periods drier.

Figure 10:  Decadal Mean Rainfall- Cairns

Figure 11:  Decadal Mean Rainfall- Alice Springs

It seems that dry periods are getting wetter at Cairns and Alice Springs, and apart from the 1970s-1980s, wet periods show no great difference.

Figure 12:  Decadal Mean Rainfall- Adelaide

Here we see the gradual fall off in rainfall in southern SA, gradually since the 1930s but more rapidly since the 1970s.  The shift in the Southern Annular Mode has caused drying in southern parts of the continent.  It is too early to draw any conclusions from that.

The alternately wet – dry feature of Australian climate is obvious from all the above plots.  However, wet periods are not getting wetter, and dry periods are not getting drier.

What about cyclones?  Here is a plot straight from the Bureau:

Figure 13:  Tropical Cyclones 1970-2021

Cyclones are NOT becoming more frequent or more severe.  The trend is clearly downwards.

Finally, heatwaves.  In reality we have no idea, as the temperature record managed by the Bureau is so bastardised- as shown here, here, here, here, here, and here.  We just don’t know, no matter what they claim.

Those who live in the cities, who have little contact with nature, and who have no knowledge of the history of Australia’s climate, will accept whatever they’re told about natural disasters as gospel.  The truth is different.

Scomo has nothing to worry about (apart from the next election).  Australia is NOT getting harder to live in: floods, fires, droughts, and cyclones are NOT getting worse or more frequent. 

UPDATE: Big M has kindly supplied this link, which I missed.

https://www.abc.net.au/news/2021-05-26/australias-hidden-history-of-megadroughts/100160174

The 1760s WA drought seems to match data from the Barrier Reef showing a 30 year drought in NQ.

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How Unusual Is All This Rain We’ve Had?

March 3, 2022

Yesterday, 2nd March, ABC weather reporter Kate Doyle posed this question on the ABC website about the recent rain event in SE Queensland and Northern NSW.

Her answer to the above question was:

Very unusual.

The rainfall totals from this event have been staggering. 

From 9am Thursday to 9am Monday three stations recorded over a metre of rain:

– 1637mm at Mount Glorious, QLD 
– 1180mm at Pomona, QLD
– 1094mm at Bracken Ridge “

She goes on to say:  “South-east Queensland and northern NSW are historically flood prone and have certainly flooded before but this event is definitely different from those we have seen in the past.”  And of course climate change is involved.

Time for a reality check. 

My answer to Kate’s question:  Not very unusual at all.

I went looking at Climate Data Online for four day rainfall totals over one metre, to compare with the recent totals above at Mount Glorious, Pomona, and Bracken Ridge. 

For a start, Pomona’s BOM station has been closed for years, and Bracken Ridge is not listed at all, so those reports are from rain gauges external to the BOM network and can’t be checked. 

That’s OK.  In about half an hour I found the following four day rainfall records.

Crohamhurst4/2/18931963.6mm
Yandina3/2/18931597.8mm
Tully Sugar Mill13/02/19271421.3mm
Palmwoods4/2/18931244.6mm
Buderim3/2/18931150.3mm
Bloomsbury20/01/19701141.8mm
Dalrymple Heights6/04/19891141mm
Innisfail3/04/19111075.8mm
Nambour11/1/18981013mm

1893 was a wet year!  Crohamhurst had 2023.8 in five days, and Brisbane had three floods in two weeks in February and another in June.

And there is no such thing as a “rain bomb”, a term invented to make it sound unprecedented.  This was an entirely natural and normal rain event.  Slow moving tropical lows drift south every few years in the wet season, producing a large proportion of Queensland’s average rainfall.

Floods have affected Brisbane and surrounds since before European settlement.  The Bureau has an excellent compilation of accounts of past floods at

http://www.bom.gov.au/qld/flood/fld_history/brisbane_history.shtml

It includes this graphic showing the height of known floods.  I have added an indication of the height of the 2022 flood.

Here are some notable Brisbane floods:

1825       a flood probably as high as the 1893 flood

1841       8.43m

1844       about1.2 metres lower than 1841

1864       ?

1887       ?

1889       ?

1890       ?

1893       8.35m

“              8.09m

“              ?

“              ?

1908       4.48m

1974       5.45m

2011       4.46m

2022       3.85m

Every flood is different- water backs up higher in unexpected places, or gets away faster, so for many people this flood was worse than 2011.  However it is beyond any doubt that this flood, heartbreaking as it was for many people, could have been much worse.  It was nowhere near as big as several in the past.  Wivenhoe Dam worked as planned this time, which greatly lessened the impact.

Another thing worth remembering:  floods were more frequent and higher in the 19th Century than they have been in the last 100 years.

ABC journalists need to do a lot more research.