Record polar vortex last November

The southern polar vortex
The southern polar vortex. NASA image

We had powerful gales in southern Tasmania in December, after a fairly wet early November.

Gales are hardly abnormal here, but these seemed special, anecdotally speaking, based on my 10 years on the farm.

In Judbury, the grass up the hill was pressed hard against the ground for three days in footage from my trailcam video.

A tree fell locally and killed two cows.

Even when it wasn’t a gale front, it blew hard.

There was plenty of drizzle in December, but it evaporated off the soil. Very little soaked in.

Interestingly, the southern hemisphere had a record strong polar vortex event in November 2020 before the gales.

The polar vortex is the wind that spins around the earth’s poles at high altitude.

When the vortex is strong and cold over the South Pole it brings rain to Australia’s East Coast, and low temperatures.

When the vortex is weak, it brings drought, heat and fires.

I am unsure if the vortex brought the gales, as the vortex is 30km high, separate from land and ocean winds.

But it does affect the weather in complex ways.

Here’s the kicker, 2019 was an unusually weak vortex year, with sudden stratospheric warming.

The 2019 Australian fires were a true disaster.

Right now the North Pole is having a vortex breakdown, something that happens more often with global warming.

This brings unusual blizzards to some northern hemisphere countries, and when that happens climate change deniers say: “Look, it’s getting colder!”

What they don’t see, unless they look for it online, is the huge lump of heat over Greenland that forms during vortex breakdowns.

If you have been paying attention, you’d know Greenland ice melt has been off the scale in recent years, and being a massive ice sheet sitting on land, it’s melt will raise global sea levels.

We live in interesting times.

Sounds of the Weld

I don’t know what this sound is, some type of owl?

Tried listening to YouTube clips of owls and other birds and none of them match.

It was a persistent call, going for at least half an hour, but sometimes just for a few minutes.

I recorded it in the Weld Valley in the evening and early morning, and have also heard it recently at night in Judbury.

Don’t recall hearing it before in my 10 years in Tasmania, but I do tend to pay more attention these days, maybe I just missed it.

Gibbons? 🙂

Paddock Life

Those who cross paths with a thylacine tend to go silly, with their new life quest being the pursuit of visual evidence to prove they aren’t a fringe-dwelling nutter.

So far, despite the wonders of affordable no-glow trailcams, camera drones and what-not, Tasmania’s surviving thylacines have remained elusive, leaving witnesses gibbering to anyone who’ll listen how the animals are still here, but without the witness being able to provide actual proof.

Fortunately, the pursuit of tiger evidence is not without its rewards, even when tigers don’t show.

Our hidden cameras and evening wanderings with a Canon SLR have picked up several devils, some of which do not have facial cancers, eastern bandicoots, feral cats, wombats, wallabies great and small, echidnas, possums with their young, eagles, and other birds.

The big devil in the picture above does unfortunately appear to have a lump on its jaw, but it is hard to know if it is a cancer or the jawline.

The photo is interesting because it demonstrates that sheep aren’t too fussed by them being around, although the youngest lambs might disagree, as three of our late ones simply disappeared this year.

Meanwhile, we wait patiently for the thylacines’ return. It has been a long eight years and I hope they hurry, as I can’t live forever, and battery purchases for my trail cameras are sending me broke.

For those of you who read this at the time of posting, have a great Xmas.

Rain, with thylacines …

The data tells the story … we’ve had good rain in the Huon in the first week of October, but the Weather Bureau rainfall anomaly map for September (top image) shows below-average rainfall in the south-west and west of Tasmania.

Lake Gordon is still half empty (bottom image).

It wasn’t long ago when Lake Gordon hit a record low of 46m below full capacity.

That was in March 2016, during a drought, and when the Bass Strait cable also broke, creating extra hydro-power demand.

The lake was so low the government worried that silt might damage the turbines.

On a lighter note, watch the impressive video below and try to tell me thylacines are not still here.

Miles and miles of rugged country where no one sets foot.

The bounty-hunting tiger trappers who plied the state from the 1830s didn’t hit the remote south-west much because it was hard country and not as productive.

However, it was well-noted that thylacines lived in rugged country right across the state.

The south-west was known to have fewer animals of all kinds than the fertile north, but thylacines were recorded there.

They were recorded in the Huon, including the “Monster of Mountain River”, an animal that scared some locals in 1949 before (apparently) disappearing back into the wilderness.

Often repeated claims that thylacines only lived on the plains are untrue, as historic reports make it clear they liked rugged areas away from people.

As a Tasmanian of 10 years, living on a farm that borders the south-west wilderness, the mystery for me is no longer whether they exist.

The mystery is why they have not grown in numbers and moved back to areas they were once known to inhabit, given that they are no longer culled by bounty hunters, and have presumably survived the mange disease that greatly lessened their numbers around 1910.

Are there too many domestic and feral dogs around now, scaring them off?

Or is it because the Tasmanian emus, which went extinct in the 1860s, are no longer a reliable food source to bring them out into more open country?

Thylacines were rarely seen even before the bounty days. They were always elusive.

The thing that changed somewhere along the way was that people stopped believing the eyewitness reports.

Thylacine sightings never stopped. It is unlikely all the witnesses are deluded or mistaken.

The great Tasmanian fox cull around 2012 was arguably the true delusion, but there were dollars to be made, so perhaps it wasn’t so crazy for those involved.

Yip yip!

Tasmania’s wild south-west as viewed from a light aircraft

The $1000 radiator bill

The heat is on
The heat is on

I recently installed ducting to all the bedrooms, putting the air intake near the woodheater flue.

It was an easy job, assembled using an eBay kit and a few extra parts, with the wiring left for the pros.

I had them install a cheap bar-style radiator on the wall under the air intake for when I had no firewood, or for when a really cold blast hits.

The radiator was doing a great job on its own so I left it on for much of the time over slightly more than month.

Then the quarterly power bill came in – $1000 above normal!

I can’t say the increase was solely from the radiator, as I used the wall panels a little more than usual, but I suspect it was the bulk of the cost.

The scary thing is that my radiator is wired into the heat tariff circuit, which is less than a quarter of the cost of the standard power.

The unit came with a standard 240v plug, which means most people would just connect it to the expensive standard tariff.

I know – radiators use a lot of juice and I should have done the maths first yada yada – but it was still a shock.

I think of folk on pensions who buy a similar radiator and plug it into their wall socket in winter, and are then hit with the bill. Ouch.

Any doubt about firewood providing cheaper heating has been dispelled, even after the cost of chainsaws, chains, oil, petrol and time.

I’ll continue cutting my own firewood as it is the cheapest way to go.

Heat pumps are of course best for electrical efficiency, but there is a big spend required up front.

Lastly, under the current tariffs my 5.5kw solar system is near useless, just $150 off the bill. I don’t know why people would bother with new systems now in Tassie, although the return is better during the long summer days.

I am considering building a small wind turbine to power the radiator.

If only we could tap into all the hot air coming out of politics these days.

Observations from a Huon farm

Rain anomalies for the two months before September
Rain anomalies for the two months before September

This winter rain has finally put water back into the soil of our farm after two very dry years.

I dug a post hole last week and the soil was wet to the bottom.

Our top dam, which dried out last summer for the first time in our 10 years here, is now full.

It has been a great time to dig trenches for water pipes, as the soil is soft and workable instead of rock hard.

What does the Weather Bureau data say about the winter rain?

Surprisingly, the anomaly map shows that the past two months of rain in the Huon region was below average.

It also shows that the severe dry trend on the once sodden West Coast continues.

I am chuffed that it has rained, as all the tanks are full.

There has been a lot of life in the forest too, when it warms up the birds are singing and there is a real evening chorus.

Other nights it is dead quiet.

The snow that falls during cold fronts doesn’t seem to last long on the Snowy Range these days, but maybe that is just me worrying about global warming.

Or maybe it is because of global warming.

A La Nina weather pattern is developing as I write this.

La Nina tends to bring flood rather than fire to Australia.

The Top End has had two terrible rainfall years and barramundi fishing has been hit hard.

La Nina tends to bring a good wet season to the north.

It remains to be seen what it brings southern Tasmania, but hopefully it will be a wet, fire-free summer.

Meanwhile, I filmed two big devils on our nightcam, and both were free of the facial cancer.

One of them was huge, being about the same rough size as the grown Bennetts wallaby carcass it stood by.

I also filmed a couple of small ginger quolls and an eastern bandicoot.

The big black quolls don’t seem to be around here as they once were.

There are many wallabies and possums, and wombat poo everywhere.

There’s a lot of life here, we are lucky to live in this paradise.

Winter and spring is a good time here.

Cumbungi, dams and dementia

Cumbungi - might it be useful? Image used under Creative Commons licence.
Cumbungi – might it be useful? Image used under Creative Commons licence.

Cumbungi or bullrush is a weed that commonly infests Tasmanian dams.

It is considered a pest, but could it be beneficial in some circumstances?

There is a global trend for even historically clean waterbodies to turn green, the result of warmer temperatures, more sunlight, lower water levels and added nutrients.

The colour is caused by blue-green algae, which is surprisingly nasty stuff.

Blue-green algae contamination of drinking water and food has been linked to fatal motor neurone disease and dementia, the suggested cause being a combination of exposure to the neurotoxic amino acid BMAA, along with genetic susceptibility in some individuals.

Might cumbungi be useful?

Cumbungi and silt had built up in my dams so I had them dug out with an excavator.

When cumbungi was present the dam water was clear most of the time, and without cumbungi the water went bright green in summer.

Cumbungi, being thick and tall, shielded much of the water from sunlight, which presumably lessened algal growth.

I expect cumbungi also pulled nutrients from the water, such as those from washed-in animal poo.

There was also life in the cumbungi – frogs and birds liked it. They went away with the cumbungi removal.

Cumbungi is deemed a problem because it “clogs dams, reduces capacity and may pollute water when it dies off in autumn/winter”.

Given that many farm dams only need to retain enough water for stock to drink in summer, reduced capacity from cumbungi may not be an issue.

As a livestock farmer, water quality is more important to me than water quantity, as long as it doesn’t run out.

Cumbungi may use water, but it may also reduce wind and light-driven evaporation.

There is evidence that using blue-green algae contaminated water in agriculture may introduce toxic BMAA into the food supply, something to consider if you are using green water to grow vegetables and feed livestock.

So, given the risks of BMAA exposure, is summer cumbungi growth potentially useful?

I have not noticed water quality problems when the cumbungi dies off in autumn/winter, but that does not mean all dams may be unaffected.

Here’s a few links meanwhile …

Tasmania’s DPI cumbungi page
BMAA and Parkinson’s disease
BMAA in Australian waterbodies
How farms make BMAA

Late edit: BMAA from hot waterholes may be to blame in the deaths of dozens of elephants in Africa.

12 years of growth

She Oak Hill tree coverage 12 years apart ... images from Google Earth
She Oak Hill tree coverage 12 years apart … images from Google Earth

She Oak Hill is located on the upper settled part of the Huon Valley in Judbury.

These two satellite images are from the north face, which is the drier, warmer side of the hill.

The zoom level and location are roughly the same.

It appears the hill was cleared some time before 2005, perhaps by fire, or for farming – I do not know which.

She Oak Hill was presumably named after its Tasmanian casuarina cover.

Today, the she oak canopy is extremely thick.

Many of the large eucalypts that poke above the she oak “blanket” were damaged or killed in a fire some time around 2009/2010, and stand as skeletons.

Locals have told me that “back in the day” they would have burned such a dry hill before the undergrowth got so thick.

“Why not burn it now?” I ask.

Apparently organising such things is no longer as simple as it was.

The sheep like eating the casuarina, probably an important addition to their diet.

The wood burns well in a heater, although it seems wasteful to burn such an attractive, workable timber … see it here.

The wind grows stronger

Trends in wind speeds
Trends in global wind speeds … graph adapted from study by Zhenzong Zend et al 2019

We are told constantly the planet is getting warmer, but wind speed trends are rarely mentioned.

The graph above shows wind speed trends over land.

There was a downward trend until 2010, then it started getting windier.

Wind speeds over the sea have been going up for decades, with a study showing the fastest increase in the Southern Ocean.

Young and Ribal [2019] assessed trends in oceanic wind speed and wave height from 1985 to 2018 using satellite altimeters, radiometers and scatterometers.

“The largest increases occur in the Southern Ocean. Confidence in the results is strengthened because the trends were confirmed by all three satellite systems,” they said.

It is a mystery why land wind speeds went down, while sea wind speeds increased.

But make no mistake, land and sea wind speeds are now both going up and will shape Tasmania’s future.

The state is already a windy place, being located in the Roaring 40s wind belt.

Gaining access to local historic wind speed data is unfortunately not as easy as obtaining rain and temperature records.

We know it is getting warmer.

Rainfall trends are harder to assess, because annual rainfall totals only tell part of the story.

The Bureau of Meteorology acknowledges that the timing of annual rainfall has changed in Tasmania.

This is where I fall back on local anecdotes.

What I have seen in 10 years on a Huon rural property is a drying trend.

There is less drizzle, but more short, heavy deluges.

There seems to be more wind, and warmer summer temperatures.

Normally I would put this down to decadal variation, but what I see matches current observations elsewhere.

What’s it all mean?

Where wind, warmth and rain intersect is in evaporation.

More wind and warmth creates dry soil and dry forests, even if rainfall remains static.

Dry forests burn, especially when it is windy.

We are seeing a recipe brewing for repeated epic bushfire seasons in Tasmania.

It is hard to imagine a bushfire as I look outside today at the lush green hills and thick fog over the river.

But the reliable spring and summer gales, the cracked soil around the dams, and the hundreds of dead trees on the hills are a huge hint.

Hopefully our community managers are taking notice of the brewing recipe.

It’s not hand-wringing time, but it is time to be prepared.

For rural dwellers, fire pumps and fuel removal strategies are essential, and you should have ember-intrusion prevention measures.

If you want to know more about wind trends, look up Australia’s wind and hydrology expert at CSIRO, Tim McVicar.

Meanwhile, here’s a recent story about the latest Australian weather trends.

Seepage-fed dam tells a story

This Huon Valley spring-fed dam was almost dry in June ... will there be adequate rain this year?
This Huon dam was almost dry in June … will there be adequate rain this year?

Yesterday, before the rain set in, our spring-fed dam (pictured above) was empty.

I use the term “spring-fed” loosely, as the dam is recharged slowly by seepage from surrounding waterlogged soil, and an occasional flooding downpour.

The dam is located in a gully in the upper settled Huon.

In my 10 years on the property it has never before dried up, and has mostly remained full.

A reliable dam located below it was low too, so the low water is not caused by leaks.

The last two summers seemed to remove most moisture from the ground.

Globally, data shows it is getting windier and warmer, which assists evaporation.

Anecdotally, it seems to be getting windier and warmer on our property.

We have had 40C days and the pasture around the dams started cracking.

Fortunately, we are now having the famous Huon winter drizzle.

Drizzle does the vital job of soaking the ground.

Short, hard rains on dry soil tend to just run off.

Downpours of the past two years failed to raise the dams much.

My first year here, the ground became so sodden from drizzle that some concreted-in timber fence posts leaned over.

Given how dry the deeper soil is now we will need a few days of drizzle to get things back to the way they were.

Tasmania’s fire website has shown that soil and fuel dryness the past two years has likely worsened bushfires.

“People once only needed one water tank around here, but not any more,” the water delivery man told me last year.

The climate is changing, but for now, hopefully the rain will hang around a while.

Global trends suggest this coming summer will be warmer and windier.

As the northern hemisphere swelters through its summer, Siberia is again experiencing extended hot periods, heat records, and is on fire.

Fire prep on our Huon property continues even as the drizzle and pea-souper fogs roll through.

EDIT: Hobart’s Mt Wellington received about 250mm of rain over June 21-22. In the Huon, the pastures now seem soaked, I’ll dig down into the soil for a look some time this week.

Tasmanian Life