[Rockhounds] Scientists match Earth's ice age cycles with orbital shifts

[Dora Smith]

I've done just a little more work on volcanoes and ice ages, and what 
I'm seeing makes sense.  It isn't quite true that no people outside of 
Africa survived the Toba eruption.  Some survived it in India, but far 
fewer than survived it anywhere else.   These supereruptions do not 
cause hundreds or thousands of years of volcanic winter.  Typically they 
cause a couple of years of it (often, as I understand, followed by heat 
and drought).   Neither Toba nor the eruption in South America would 
have caused an ice age by itself, but calendar wise they occurred as an 
ice age was about to start.

The fun and games in 536 AD may have been a pair of supervolcanoes that 
erupted close together, not as large as Toba and its companion, and 
there was about ten years of severe disruption to the environment, that 
caused famine, disease outbreaks like the plague, and problems with 
feeding livestock on the steppes, which reorganized the planet 
politically.  Even regimes in central and south America fell.

Yours,

Dora

On 3/1/25 5:32 PM, Dora Smith wrote:
> I just sent three replies to the person who wrote the posts instead of 
> the list.
>
> This (changes in earth's orbit) isn't at all a new idea, but, I 
> believe the correspondence is far from exact and other things play a 
> role.  Before the western hemisphere took its current configuration 
> there weren't ice ages!
>
> There have been extremely long periods of earth's history lasting a 
> billion years or more where the entire planet was outright hot.
>
>
> -------------------------------------------------------------------
>
> How did this eruption compare with the Tobo supervolcano around the 
> same time, that is thought to have driven the human race to the verge 
> of extinction?  It buried India under many yards of ash, and caused a 
> definite volcanic winter.  It is thought that only humans living in 
> certain parts of Africa at that time could have survived.  Humans 
> lived in Asia, but they didn't survive.
>
> The Tobo eruption is supposed to have been bigger than those of 
> Yellowstone, that would destroy civilization as we know it if it 
> erupted the same way today.   Was Los Chocoyos puny by comparison?
>
> I'm actually feeling a little skeptical, because every single time 
> scientists find a world changing eruption that changed the course of 
> humanity or civilization, someone else says oh no, this other volcano 
> in South America did it, for the sake of argument, just to deny reality.
>
> -----------------------------------
>
> Wait - what caused that ice age, the last one before the most recent 
> around 45,000 years ago - changes in Earth's orbit around the sun, or, 
> volcanic eruptions?  LOL!
>
> I have been of the opinion that a volcanic winter might help push the 
> planet into an ice age that other forces were already inclining it 
> toward.
>
> ---------------------------------------------
>
> When I looked into it, I found that this Nature article thinks both 
> eruptions caused an ice age.  I still don't think they caused it all 
> by themselves, especially not if they occurred 10,00 years apart.  
> Toba is not exactly dated.  Over the long years since it was blamed 
> for humanity's population bottleneck, I have seen 65,000 and 75,000.
>
> https://www.nature.com/articles/s43247-021-00293-6
>
> They were both huge eruptions.
>
> Yours,
>
> Dora
>
>
> On 3/1/25 1:32 PM, Kreigh Tomaszewski wrote:
>> Beginning around 2.5 million years ago, Earth entered an era marked by
>> successive ice ages and interglacial periods, emerging from the last
>> glaciation around 11,700 years ago. A new analysis suggests the onset of
>> the next ice age could be expected in 10,000 years' time.
>>
>> The findings are published
>> <https://www.science.org/doi/10.1126/science.adp3491> in the journal
>> *Science*.
>>
>> An international team, including researchers from UC Santa Barbara, made
>> their prediction based on a new interpretation of the small changes in
>> Earth's orbit of the sun, which lead to massive shifts in the planet's
>> climate over periods of thousands of years. The study tracks the natural
>> cycles of the planet's climate over a period of a million years. Their
>> findings offer new insights into Earth's dynamic climate system and
>> represent a step-change in understanding the planet's glacial cycles.
>>
>> The team examined a million-year record of climate change, which 
>> documents
>> changes in the size of land-based ice sheets across the Northern 
>> hemisphere
>> together with the temperature of the deep ocean. They were able to match
>> these changes with small cyclical variations in the shape of Earth's 
>> orbit
>> of the sun, its wobble, and the angle at which its axis is tilted.
>>
>> https://phys.org/news/2025-02-scientists-earth-ice-age-orbital.html
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