After the deluge

My town was hit by a monster storm on Friday 20th of February 2015.  At least that’s how the media reported it.  They were thick on the ground.  If you couldn’t get interviewed for TV then you weren’t trying.  I at first said no on principle.  Never say yes first off to a bright, young person with a big smile.  Besides – what could I say about being at Wreck Point with a cyclone imminent without sounding like a berk?

It started at 4.00am with an automated evacuation alert to both my mobile phone and the landline.  I put my cyclone plan into action – which involved bacon, eggs, fresh rolls, butter and an ample supply of medium roast Capricorn Coast Coffee grounds.  The cyclone breakfast of choice.  We duly evacuated to the Police Citizens Youth Club by 5.00am as advised – but the authorities thought better of this and sent us on to the high school gymnasium.  We were between shelters and took the opportunity to have a peek at the coming storm.

Our day was spent locked up with some 700 people.  I could see snatches of the storm from behind reinforced windows and could hear the wind – if I listened for it – high across the roof.  I followed the storm on my phone in radar loops and 10 minute observations from the Bureau of Meteorology.  Wind gusts peaked in Yeppoon at 150km/hr – the highest in the cyclone path.  Nothing to be trifled with – but not unprecedented even over the last 100 years.  The lowest pressure as the system passed was 996.3 hPa.  Make the comparison with historic storms.  After being released – what I saw of the damage locally was by and large confined to pre 1984 housing – along with lots of trees that had matured since the last cyclone.  Post 1984 housing is much stronger.

Despite the hype – and the global warming opportunism – it was not anywhere near the monster nature can – and will in future – throw at us.   We get the occasional cyclone – and big ones – south of the Tropic of Capricorn.  Cyclones arise as a result of evaporation from warm oceans being spun up by the rotation of the Earth.  They originate in the Coral Sea – generally south of 10 degrees of latitude – and take an erratic path down the Australian coastline.  They hit the coastline and become a tropical low pressure system or weaken in cooler southern waters.

Cyclones are much more frequent and intense – in Australia – when the Pacific Ocean is in the La Niña state.  Stronger trade winds in the cooler ocean mode since early in this century have pushed warm water up against Australia and Indonesia increasing the frequency and intensity of cyclones.  The relative frequency and intensity of the two states – El Niño and La Niña – changes over decades to millennia.  Christopher Moy and colleagues published some interesting work in 2002 on lake sediment at Laguna Pallcacocha in southern Ecuador.  It traces the El Niño-Southern Oscillation (ENSO) across the Holocene.

It is based on the presence of more or less red sediment in a lake core. More sedimentation is associated with El Niño. The record has continuous high resolution coverage over 11,000 years. It shows periods of high and low El Niño activity alternating with a period of about 2,000 years. There was a shift from La Niña dominance to El Niño dominance that was identified by Anastasios Tsonis  as a chaotic bifurcation – and is associated with the drying of the Sahel. There is a period around 3,500 years ago of high El Niño activity associated with extended drought and the demise of the Minoan civilisation (Tsonis et al, 2010).  Red intensity during the Minoan decline exceeded 200.  For comparison – the red intensity during the 1997/98 ‘super’ El Niño was 99.

Tsonis 2009 Figure 1

Figure 1:  Red intensity in a lake core at Laguna Pallcacocha, southern Ecuador

We can look more closely at the last 1000 years of ENSO in work done by Tessa Vance and colleagues on salt content in an ice core at the Law Dome in Antarctica.  More salt is deposited in the La Niña state.  In great detail it shows the 20 to 30 year periodicity of cool and warm regimes, the variability of the timing of shifts between El Niño and La Niña, drier conditions in Australia during the past century (as well as 1000 year ago) and the dominance of the La Niña state in the past millennia.  The reasons for these dramatic changes are not known.  As well as influencing cyclones and planetary scale rainfall – El Niño result in a warmer atmosphere and have increased in frequency over the past century.

Vance2012-Antartica Law Dome ice core salt content  

Figure 2:  Salt content in an ice core at the Law Dome showing the dominance of La Niña

The findings are consistent with work done by Jonathon Nott on cyclone intensity and frequency on the Australian coastline.  Professor Nott found that the current period has historically low cyclone activity.  His work on nature’s extremes more generally shows drought and storms much greater than anything seen in the past century.

We have been without power for three days now.  I am writing this by candlelight.  No refrigeration, washing machines, air conditioning or – the thing I miss the most – the dish washer.  It is the little things that go first.  Shaving and wearing underpants in my case.   Thus civilization falls.  The United Nations has suggested that enough power for a light, a fan and a radio for a few hours a day is sufficient.  We have that – it is nowhere near enough.  Resilience to nature’s extreme comes from prosperity – and any future global civilization worthy of the name is on a high energy planet.  From my dining room table I can see sections of the town lit up that weren’t yesterday – fuelled by coal.

I have finished clearing the felled trees – and removing the garden shed that showed up during the storm.  It is hot and tiring work and we are all over it and want to get back to our lives.  More seriously – the girl next door packed up her baby and left town for a few days after two trips with the baby to the emergency room – suffering from heat stress.

The spirit is one of forbearance, fortitude, humour and mutual assistance.  The great Australian tradition of fighting fire, flood, pestilence or war side by side.  An example – a grocery stacker at a local supermarket had worked 20 hours overtime in a couple of days keeping food supplies moving – and offered to work for free.  Just an ordinary Australian hero.  In the larger sense this is in fact a heartening story of successful emergency planning and management – and the strength of ordinary people.  It is a story we should take some time to celebrate – things worked very well indeed – keeping in mind that it is a story that will be told again.  As the poet said – a hard rains gunna fall.

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