Australia is on fire

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nefibach
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Re: Australia is on fire

Post by nefibach » Sat Feb 15, 2020 9:00 pm

Herainestold wrote:
Fri Feb 14, 2020 10:28 pm
We are in a new geological era, where the old rules do not hold.

Because of human induced influences catstrophic changes can happen instantly with no warning.

Look at corona virus for instance.
The existence of a new geological era, and 'anthropocene' is far from settled science.
Old geological rules still hold.
Geological catastrophes are entirely separate from human-induced catastrophes, and most of the human ones do have some form of warning it's just that we don't pay attention. Some geological ones come with warning signs as well, though some of the most dramatic do not.
Coronavirus is not an example of anything geological.

nefibach
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Re: Australia is on fire

Post by nefibach » Sat Feb 15, 2020 9:03 pm

plodder wrote:
Mon Feb 10, 2020 11:59 am
Cool thanks. This fits with the position that rare and extreme events are far more influential in shaping the physical world than gradual small processes. For example, rivers tend to change course after big floods or other erosive events rather than gradually moving. Note “tend” - lots of factors in play.
A vast amount of the physical world is the shape it is because of extremely slow processes that take place over millions of years. Sudden and extreme events affect really a quite a small percentage of the observable world, but they happen on a human scale, which is why we notice them more than the long, slow processes.

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jimbob
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Re: Australia is on fire

Post by jimbob » Sat Feb 15, 2020 9:20 pm

nefibach wrote:
Sat Feb 15, 2020 9:00 pm
Herainestold wrote:
Fri Feb 14, 2020 10:28 pm
We are in a new geological era, where the old rules do not hold.

Because of human induced influences catstrophic changes can happen instantly with no warning.

Look at corona virus for instance.
The existence of a new geological era, and 'anthropocene' is far from settled science.
Old geological rules still hold.
Geological catastrophes are entirely separate from human-induced catastrophes, and most of the human ones do have some form of warning it's just that we don't pay attention. Some geological ones come with warning signs as well, though some of the most dramatic do not.
Coronavirus is not an example of anything geological.
I recall reading in one of my brother's undergrad textbooks in the 1990s that human activity moved more rock than natural processes in the continent of North America, and given the situation in China (a few years this decade using more concrete than the US in the whole of the 20th Century according to the World Service).

I'd say one could argue that humanity is the most significant geological influence on one (maybe two) continents based on this alone.

Then you have the effects of global warming. And the effects on flora and fauna. It seems pretty reasonable to define the current era as the anthropocene
Have you considered stupidity as an explanation

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Re: Australia is on fire

Post by plodder » Sun Feb 16, 2020 4:19 am

OK. I’m pretty sure that rather than the daily breath of wind or patter of rain eroding mountains over millions of years, it’s the annual (or five year) storm that does the shaping (over millions of years)

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Re: Australia is on fire

Post by Herainestold » Sun Feb 16, 2020 4:38 am

plodder wrote:
Sun Feb 16, 2020 4:19 am
OK. I’m pretty sure that rather than the daily breath of wind or patter of rain eroding mountains over millions of years, it’s the annual (or five year) storm that does the shaping (over millions of years)
Its both. In some sediments, millions of years old, you can trace daily tidal patterns. Big events like a major hurricane can change river mouths by miles. You can see those events in the stratigraphic record too.
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Re: Australia is on fire

Post by plodder » Sun Feb 16, 2020 4:51 am

Yeah, OK.

Can’t find the actual equations I’m looking for, but geomorphology is essentially the study of sediment transport. Here’s a good summary, that also explains why, most of the time, under ‘low’ energy conditions, you get temporary equilibrium:

3.2.3 Sediment Transport
Transport Mechanics
Transfers of material in the fluvial system take place through the transport of sediment downstream from erosive source to depositionary sink. It is, therefore, sediment transport that links up the fluvial transfer system. For sediment transport to occur, two conditions must be met:
1. Flow must be sufficiently vigorous to carry available sediment along with it;
2. Sediment of a calibre that can be carried must be available for transport.

from p99 of http://randd.defra.gov.uk/Document.aspx ... 47_TRP.pdf

for more info on the various factors at play etc start around p45, it’s easy reading

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Re: Australia is on fire

Post by dyqik » Sun Feb 16, 2020 5:33 pm

Not relevant to Australia, but things like regular frosts and thaws loosen rock and destabilize the structure, but then it's a big freeze/gale/rainstorm that moves that loosened rock significant distances.

Similarly for glaciers calving - gentle warmth weakens the structure, undermining the glacier and giving it space to flex, and then a big storm breaks icebergs off.

Something a bit like that is also what happens to chalk and sandstone cliffs, which I'm guessing you're (plodder) familiar with. Or with landslides on hills. Gradual processes like loss of stabilizing roots or leaching of organic matter happen slowly, and then a big flood/runoff event provides enough force to cause a significant movement.

The gradual process generates the supply in your 2., and then the big event provides the impetus in 1.

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Re: Australia is on fire

Post by bjn » Sun Feb 16, 2020 7:19 pm

dyqik wrote:
Sun Feb 16, 2020 5:33 pm
Not relevant to Australia, but things like regular frosts and thaws loosen rock and destabilize the structure, but then it's a big freeze/gale/rainstorm that moves that loosened rock significant distances.
Ahem...

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Re: Australia is on fire

Post by dyqik » Sun Feb 16, 2020 10:52 pm

bjn wrote:
Sun Feb 16, 2020 7:19 pm
dyqik wrote:
Sun Feb 16, 2020 5:33 pm
Not relevant to Australia, but things like regular frosts and thaws loosen rock and destabilize the structure, but then it's a big freeze/gale/rainstorm that moves that loosened rock significant distances.
Ahem...

Image
Feel free to insert the word "mostly" wherever the word "entirely" or "absolutely" isn't used.

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bjn
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Re: Australia is on fire

Post by bjn » Sun Feb 16, 2020 11:47 pm

The snowfields of Australia are bigger than Switzerland, and frosts are common in the deserts during winter nights.

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Re: Australia is on fire

Post by plodder » Mon Feb 17, 2020 7:16 am

dyqik wrote:
Sun Feb 16, 2020 5:33 pm
Not relevant to Australia, but things like regular frosts and thaws loosen rock and destabilize the structure, but then it's a big freeze/gale/rainstorm that moves that loosened rock significant distances.

Similarly for glaciers calving - gentle warmth weakens the structure, undermining the glacier and giving it space to flex, and then a big storm breaks icebergs off.

Something a bit like that is also what happens to chalk and sandstone cliffs, which I'm guessing you're (plodder) familiar with. Or with landslides on hills. Gradual processes like loss of stabilizing roots or leaching of organic matter happen slowly, and then a big flood/runoff event provides enough force to cause a significant movement.

The gradual process generates the supply in your 2., and then the big event provides the impetus in 1.
River morphology is a little different, with periods of equilibrium. Not entirely sure how the analogy transfers to geomorphology in general, or what the effect of daily wetting/drying or heating/cooling is, but I wouldn’t be at all surprised if it’s the sum total of f.ck-all and just something they teach kids because it’s almost right, it’s simple and it captures the imagination.

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Re: Australia is on fire

Post by Allo V Psycho » Mon Feb 17, 2020 2:38 pm

Just been speaking to a colleague in Australia, who 5 weeks ago had to pack family, pets and passports to flee a bush fire of half a million hectares, 5k from their house.
This week they are home: filling sandbags because of the imminent floods.

Edit spell

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dyqik
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Re: Australia is on fire

Post by dyqik » Mon Feb 17, 2020 3:28 pm

plodder wrote:
Mon Feb 17, 2020 7:16 am
dyqik wrote:
Sun Feb 16, 2020 5:33 pm
Not relevant to Australia, but things like regular frosts and thaws loosen rock and destabilize the structure, but then it's a big freeze/gale/rainstorm that moves that loosened rock significant distances.

Similarly for glaciers calving - gentle warmth weakens the structure, undermining the glacier and giving it space to flex, and then a big storm breaks icebergs off.

Something a bit like that is also what happens to chalk and sandstone cliffs, which I'm guessing you're (plodder) familiar with. Or with landslides on hills. Gradual processes like loss of stabilizing roots or leaching of organic matter happen slowly, and then a big flood/runoff event provides enough force to cause a significant movement.

The gradual process generates the supply in your 2., and then the big event provides the impetus in 1.
River morphology is a little different, with periods of equilibrium. Not entirely sure how the analogy transfers to geomorphology in general, or what the effect of daily wetting/drying or heating/cooling is, but I wouldn’t be at all surprised if it’s the sum total of f.ck-all and just something they teach kids because it’s almost right, it’s simple and it captures the imagination.
You can make the very general "gradual build up of pressure, sudden event causes visible change" model work for oxbow lakes getting cut off, at least (neck of land in a meander narrows gradually, probably with greatest erosion happening during flood/rain events when flow is highest, another flooding event allows water to overflow neck and cut a channel or push through). And probably for erosion and break-through in other situations as well. But that's about the limit of my GCSE river geography (plus some general stuff from degree level materials science), and I'm guessing at the correct terms.

Generally though erosion of any kind isn't a steady continuous process when you look at it on short timescales, it's an episodic thing. At the shortest timescales, each rain or wind storm causes a small step of erosion, with nothing happening in the dry calm periods in between.

Both the gradual build up of small steps and the final proximate cause event are important though.

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jimbob
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Re: Australia is on fire

Post by jimbob » Mon Feb 17, 2020 6:05 pm

bjn wrote:
Sun Feb 16, 2020 11:47 pm
The snowfields of Australia are bigger than Switzerland, and frosts are common in the deserts during winter nights.
I'm guessing there isn't that much moisture in the deserts for freeze-thaw to generally be significant. Not like Scotland, where you have rain falling into the cracks in the rock then freezing.
Have you considered stupidity as an explanation

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Re: Australia is on fire

Post by Bird on a Fire » Sat Oct 31, 2020 3:02 pm

Bushfire inquiry says Australia must prepare for 'alarming outlook'
Australia must prepare for an "alarming" future of simultaneous and worsening natural disasters, says a long-awaited report into the country's bushfires.

A royal commission inquiry examined Australia's Black Summer bushfires of 2019-20 - which ravaged vast swathes of the nation - and other disasters.

At least 33 people died in what was by many measures an unprecedented season.

The report made more than 80 recommendations to the government.

They included detailed proposals to improve national response efforts, tools and climate data, among many other areas.

It also reiterated that climate change had exacerbated the extreme conditions which caused the fires, but that future projections were more grim.
The Royal Commission into National Natural Disaster Arrangements warned global warming was "inevitable" the coming two decades.

The commissioners said that "compounding disasters" would become more common - where natural hazards such as fires, floods and storms happen simultaneously, or one after another.

"To properly manage natural disasters of national scale and consequence, it is no longer suitable or appropriate to assess disaster risk at an individual hazard," they wrote in the report.

"We must assess the risk of multiple hazard events occurring concurrently or consecutively."

The report said the damage from successive disasters could be partly mitigated by how well authorities prepared.

Australia needed "strong adaptation measures" to deal with the impacts of future warming which depended on "the trajectory of greenhouse gas emissions", the commissioners added.

The inquiry, which focused on national response efforts, called for the federal government to take earlier intervention in disasters.

Some of the recommendations included:

Introducing powers to declare a national state of emergency
A better system for reporting climate data
More resources for aerial firefighting and emergency warnings
Nationally consistent fire danger ratings and air quality monitoring.
I'd add "move to a net-negative carbon balance ASAP and apply maximum pressure to other countries to do the same" to that list of recommendations, but it's probably outwith the remit of the report.

Nevertheless, we probably won't view fires like last year's as particularly unusual going forward.
We have the right to a clean, healthy, sustainable environment.

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