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Re: The Climate, Environment and Energy Thread

Reply #45 –
Quote from: Thryleon – on
I only disagree with one part of your post DJC, and that is that the evidence points to us still being in an Ice Age even though you might have stated we arent because even at a recent trivia night I attended the correct answer was that we are technically still in one, (my gut said that its true was a better trivia answer so we got the points on that one).

Your trivia master was wrong Thry  :)

This is my bread and butter; you can’t understand Australian archaeology without understanding the climatic context.  For example, the sundering of Bass and Torres Straits and the inundation of what is now the continental shelf had profound effects on the first Australians.

Stone artefacts have been found on Mud Islands in Port Phillip Bay.  While it is possible that Aboriginal people could have navigated there, it would have been an extremely risky voyage in the watercraft they had.  However, recent studies have revealed that Port Phillip Bay was dry land between 1,000 and 2,800 years ago and it would have been possible to walk to what would have been prominent dunes on Port Phillip Plain.  The major causes of the drying up of Port Phillip Bay was sand deposits blocking the Heads combined with higher than normal evaporation rates, reflecting a drier climate at that time.  Port Phillip Bay as dry land features in the oral histories of the Kulin people of central Victoria.

Technically, there are no “ice ages”, it is a lay term.  Climate scientists, geologists, archaeologists, palynologists, etc refer to glacial and inter-glacial periods.  As I said previously, glacial equates to ice age and inter-glacial is not an ice age in lay terms.

Looking at it from the perspective of the geological time scale:

The Pleistocene is the most recent period of repeated glaciations. Until recently, glaciations were a feature of the end of the Pliocene Period (the “ice age” was the Plio-Pleistocene) but the beginning of the Pleistocene has been pushed back to 2.58 Ma so that all recent repeated glaciations are within the Pleistocene era.  In other words, the Pleistocene is the “ice age”.

The Holocene refers to the last 11,700 years, that is, the time since the end of the last major glacial epoch, the Pleistocene or "ice age." There have been the small scale climate shifts since the commencement of the Holocene, including the "Little Ice Age" between about 1,200 and 1,700 CE, but that was restricted to the northern hemisphere. The defining feature of the Holocene is the relatively stable climate, as opposed to the widely fluctuation climate swings of the Pleistocene.  Note that the “Little Ice Age” almost overlaps with the period that Port Phillip Bay was dry land so while it was colder in the northern hemisphere, southern Australia was experiencing higher evaporation rates.  That does suggest warmer temperatures but a much larger part of Australia was arid during the Pleistocene as more of the water budget was locked up in ice caps and glaciers.

Where confusion can arise is the grouping together of the Pleistocene and Holocene as the Quaternary Period.  Most of the 2.59Ma of the Quaternary Period has been glacial so you could say that we are still in a period of repeated glaciation.  Of course, that ignores the fact that Holocene is defined as the period following the repeated glaciation of the Pleistocene.

On top of that is the use of Anthropocene as the most recent geological period.  I don’t think that there is agreement on when human activity became the driver of climate and environmental change but it doesn’t necessarily coincide with the Holocene period.  Many researchers push the commencement of the Anthropocene back beyond 11,700 years BP that is accepted as the end of the Pleistocene.
It's still the Gulf of Mexico, Don Old!

Re: The Climate, Environment and Energy Thread

Reply #46 –
Quote from: DJC – on
Note that the “Little Ice Age” almost overlaps with the period that Port Phillip Bay was dry land so while it was colder in the northern hemisphere, southern Australia was experiencing higher evaporation rates.  That does suggest warmer temperatures but a much larger part of Australia was arid during the Pleistocene as more of the water budget was locked up in ice caps and glaciers.
Yes, this correlation between ice caps and dry hot periods over low latitudes is frequently overlooked in climate sceptic debates. The general public's assumption is that hot means dry, when history indicates you need more ice at the caps to be dry at low latitudes in the absence of some other effect.

Just An FYI for some readers;
Low Lattiudes are near the equator, +/- 0° north or south, High Latitudes are near the poles, +/- 90° North or South. Be careful when reading about High and Low latitudes, because a term like "Down South" doesn't mean at a Low Latitiude!



Sometimes I think modern scientists should throw out the historical deference to old terminology, some of the terms used in this case were originally phrased when the debates over the earth being round, flat or hollow were still underway!
"Extremists on either side will always meet in the Middle!"

Re: The Climate, Environment and Energy Thread

Reply #47 –
I don't know about what LP posted, but i listened to a podcast on iceages and they agreed with Thry and his trivia master. We are still in the latter stages of an ice age.

I cannot recall the exact definition and where it came from, but if i had an educated guess at it, it would be the fact we still have ice on our caps.

From memory there was 3 stages. ice age, middle bit aka lesser ice age which we are in now and non-ice age. Obviously the technical jargon is not there, but the point remains.

Re: The Climate, Environment and Energy Thread

Reply #48 –
Quote from: kruddler – on
I don't know about what LP posted, but i listened to a podcast on iceages and they agreed with Thry and his trivia master. We are still in the latter stages of an ice age.

I cannot recall the exact definition and where it came from, but if i had an educated guess at it, it would be the fact we still have ice on our caps.

From memory there was 3 stages. ice age, middle bit aka lesser ice age which we are in now and non-ice age. Obviously the technical jargon is not there, but the point remains.

That was the rationale too in his explanations.

The technicality was that we have periods where the ice levels increase.



"everything you know is wrong"

Paul Hewson

Re: The Climate, Environment and Energy Thread

Reply #49 –
https://theconversation.com/climate-explained-why-we-wont-be-heading-into-an-ice-age-any-time-soon-123675

This aside though, the timing is right for the next ice age to come around soon. For the past two and a half million years, the Earth has experienced regular ice ages, related to slow changes to earth’s orbit around the sun and changes in the earth’s axis of rotation (Milankovitch cycles). We are currently in one of the warm periods (interglacials) between ice ages and the present interglacial should be ending about now. The catch is carbon dioxide.

Re: The Climate, Environment and Energy Thread

Reply #50 –
Quote from: PaulP – on
https://theconversation.com/climate-explained-why-we-wont-be-heading-into-an-ice-age-any-time-soon-123675

This aside though, the timing is right for the next ice age to come around soon. For the past two and a half million years, the Earth has experienced regular ice ages, related to slow changes to earth’s orbit around the sun and changes in the earth’s axis of rotation (Milankovitch cycles). We are currently in one of the warm periods (interglacials) between ice ages and the present interglacial should be ending about now. The catch is carbon dioxide.

About 100 years according to my research.  What that means for humanity if we solve it and it happens i find most interesting.

After all, I think a proper ice age might be worse for humanity in general.
"everything you know is wrong"

Paul Hewson

Re: The Climate, Environment and Energy Thread

Reply #51 –
I suppose the first thing you have to define when discussing the idea of glacial or inter-glacial periods is defining what either period is, some will refer to the Maunder Minimum as an Ice Age but others suggest hardly! For example what is the "period" interval, 11kyr, 19, 23, 40, 100kyr?

If it's 11kyr, and the Maunder Minimum was perhaps a sign of solar dynamics that triggered the Little Ice Age, the next seems overdue.

Fwiw, a lot of commentary denies the Maunder Minimum was an effect because it only lasted a short time in relation to the claimed period of the Little Ice Age, but of course that ignores that the possibility that the solar dynamic effect causing the Maunder Minimum were only present when low solar sunspot activity was actually being observed and detectable by the best people of the time. If the solar dynamics had no effect was it orbital dynamics, if so what changed in this regard on such a short cycle, certainly not orbital dynamics?

The problem is the best data available only goes back about 450kyr, from ice cores, and that the evidence for influences from orbital dynamics in those cores is only weak if not merely just a correlation. The Earth has precessed many times over that period, like a clock that ticks out 26kyr cycles. So much so that some even question the validity of Milankovitch cycles, if they are real, there are climate effects but it seems they are not explained by orbital dynamics. Further if they are real they most likely don't happen(that is the polite don't) in 11kyr cycles, or 23kyr, or 40kyr but closer to 500kyr cycles. Actually, a huge flaw is that if followed explicitly a modelling of the Milankovich cycle predicts asymmetric freezing and thawing of Earth's opposing poles, and that is not what happened as the record shows the whole Earth cooling or warming. I won't get into the arbitrary choices made when analysing or modelling data, it's a rabbit warren.

The take home is that orbital effects have an influence, but they are not likely to be the explanation of climate dynamics, think of them as a small contributing factor not a outright cause. It's the largess of humans to explain these things, and claim to have the answer, it's much smarter to admit there is no answer and talk about only what we know.

Humans are pattern matching machines, and we are powerless in taming this evolved ability.

Opinion.
Many will post commentaries declaring what the weather will do next century like it's a certainty!

Reality.
We have magnetic field records in rocks 4Gyr old, we have thousands of years of detailed human records about Earth's magnetic fields and fluctuations, we can measure these things with instruments more sensitive and accurate than any thermometer. Yet we can't predict where the magnetic north pole will be next year beyond a general trend in direction and speed, it's behaviour tomorrow is a mystery! It's finely detailed movement is chaotic!
"Extremists on either side will always meet in the Middle!"

Re: The Climate, Environment and Energy Thread

Reply #54 –
Quote from: PaulP – on
https://theconversation.com/up-to-90-of-electricity-from-solar-and-wind-the-cheapest-option-by-2030-csiro-analysis-151831
I'm on the fringe of this stuff having been involved with some of the R&D for quite a few years, it is based on some rather grandiose assumptions relating to storage and efficiency, for example it still requires Hydroelectric as a large scale storage medium which from a perspective of the environment is pretty damaging if not the very worst option, note hydro emits both CO2 and methane as well as destroying beyond repair many many square kilometres of high country type environments.

Each participant has to talk up their technology as it's a war to get funding to keep on developing the systems.

Base load demand will never go away, hospitals, entertainment and big industry need 24x7. There isn't a hope in hell Joe Average will turn off his TV when the footy is on just to keep a hospital from being blacked out, unless of course he has to go to hospital at which time he'll demand everybody to switch off, sorry for the cynicism!
"Extremists on either side will always meet in the Middle!"

Re: The Climate, Environment and Energy Thread

Reply #55 –
The value of Australia’s newest coal-fired power station, Bluewaters in WA, has been written down to zero, wiping out a $1.2B investment after just ten years.

Simon Nicholas, an energy finance analyst at IEEFA, says;
"In Australia, the cost of utility-scale renewables is often lower than the cost of fuel for coal-fired power plants.
So, the long-term future for coal-fired power plants is looking fairly grim and banks are responding to that — they don't want to finance coal anymore."

And the self-proclaimed champions of the free market are clamouring for more coal-fired power stations  ::)
It's still the Gulf of Mexico, Don Old!

Re: The Climate, Environment and Energy Thread

Reply #56 –
Quote from: LP – on
Opinion.
Many will post commentaries declaring what the weather will do next century like it's a certainty!

Reality.
We have magnetic field records in rocks 4Gyr old, we have thousands of years of detailed human records about Earth's magnetic fields and fluctuations, we can measure these things with instruments more sensitive and accurate than any thermometer. Yet we can't predict where the magnetic north pole will be next year beyond a general trend in direction and speed, it's behaviour tomorrow is a mystery! It's finely detailed movement is chaotic!

It’s relatively easy to interpret the past (my caper) but predicting what’s going to happen in the future is another kettle of fish altogether.

A significant unknown is whether the Anthropocene impacts will negate the forces that would normally cause a change from inter-glacial to glacial.

Then there’s asteroid strike  :o
It's still the Gulf of Mexico, Don Old!

Re: The Climate, Environment and Energy Thread

Reply #57 –
Quote from: DJC – on
Then there’s asteroid strike  :o
While I don't want to jinx us, I have to say it's very unlikely to happen in the time scale that humanity has already existed in. Also humans like immediate explanations, so they favour the asteroid as it is not something that quietly creeps up on you like a cancer, but at the moment more and more evidence is building the Deccan Traps played a much bigger role than the asteroid, and the resulting long term climate shift left dinosaurs defenceless against something as simple as fungai, but we may never know!

When people start referencing asteroids, I often wonder what the chances of a new Tambora or Krakatoa, Australia in particular should be treating this seriously in conjunction with Indonesia and New Zealand, and the effects could well be global. Yet we(governments) stand by while Italy jails seismologists, it doesn't fill me with a lot of confidence about humanity!

Interesting aside, tectonics was basically unknown when Milankovic postulated his cycles!
"Extremists on either side will always meet in the Middle!"

Re: The Climate, Environment and Energy Thread

Reply #58 –
Quote from: DJC – on
It’s relatively easy to interpret the past (my caper) but predicting what’s going to happen in the future is another kettle of fish altogether.

A significant unknown is whether the Anthropocene impacts will negate the forces that would normally cause a change from inter-glacial to glacial.

Then there’s asteroid strike  :o

Apparently this has already occurred and we are roughly 100 years late.

The issue I have is determining correlation vs causation.  We would be polluting at a much higher rate today than we were 100 years ago simply by volume.
"everything you know is wrong"

Paul Hewson