
Ancient farmers spared us from glaciers but changed Earth's climate: study - dnetesn
https://phys.org/news/2018-09-ancient-farmers-glaciers-profoundly-earth.html
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TSiege
This new research is definitely intriguing, but at the same time I think it's
fair to be skeptical of this new science. During the times of increase in
global temperatures, human populations are estimated to be between 5 to 20
million for the whole planet. That is a very low density. Not to mention human
farming began before the Younger Dryas (a sudden return to cold temperatures),
which briefly ended agriculture for over a millennia.

Also, during more recent times the earth has swung into cold spells that had
dire consequences for human populations, such as the Little Ice Age which
began in the 1300s and only ended during the beginning of the Industrial
Revolution. It's likely Earth would have continued getting colder had it not
been for the mass expelling of CO2 and methane into the atmosphere at that
time.

So maybe humans had an impact on the global atmosphere during the second
beginning of agriculture, but it's also possible other natural phenomena lead
to an increase in CO2 and Methane that just haven't been discovered yet. And
as a disclaimer, I personally believe that humans have had a major impact on
shaping environments for as long as we inhabited them. I'm just a little
skeptical until more research can solidify these findings and explain other
changes in global temps in the opposite direction when there were more people
and more intensive agriculture.

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hinkley
There’s some evidence that the Little Ice Age was caused by a sudden decrease
in farm acreage cause by sudden depopulation during the Black Death.

I hesitate to call it anthropogenic because it’s the opposite of that. I
suppose the _delay_ of the cold period counts, though.

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DrScump

      a sudden decrease in farm acreage
    

but.. it wouldn't happen that way (like throwing a switch). Crops would rot in
the field and then be _replaced_ by native plants. Is this evidence presented
in paper(s)?

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hinkley
Having trouble parsing your complaint.

The moment the farmer dies without an heir, his field is fallow. From that
point forward, whatever germinates will grow if it can compete. So pioneer
species get free reign and they can spread widely in only a few years.

The little ice age was almost 300 years. From a geologic standpoint or even a
glacial one, trees sprouting up all over in a five year time frame is pretty
sudden, but the sudden event I was talking about was acreage of unmanaged
land.

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jefflombardjr
Anyone fascinated by this article, I highly suggest reading Sapiens by Yuval
Noah Harari. I just recently picked it up after seeing it recommended on a
couple of threads here and it did not disappoint. Humans have been affecting
ecology for a long long time.

If you are like me, you're probably wondering what you can do to mitigate some
of the effects, while legislation and societal action is important. I also
recommend checking out permaculture. Portland state has a great free online
course [0]. I like to think of permaculture as ecosystem building, which you
can do on a micro level. Enough microecosystems change the larger surrounding
ecosystem.

[0]
[https://open.oregonstate.edu/courses/permaculture/](https://open.oregonstate.edu/courses/permaculture/)

~~~
adreamingsoul
Instead of courses, I recommend to get a couple books on Permaculture and also
look to see if any universities have extension courses for Permaculture or any
topic related to it. Chances are, most of the teachers are now familiar with
Permaculture and can speak to the “historical” methods and the “Permaculture”
methods. Yes, a lot of people have been trying to make money of the
cerificstion courses, which I think is a waste of money. I started with my
backyard and have used Permaculture design to re-approach working with nature.
My end goal is to have a diverse forest garden that has it’s own ecosystem.
But, that’s at least 10 years of work to achieve, but well worth it. I’m
almost two years into this and have zero regrets. If anyone is interested to
know more, I can try to share what I’ve learned or answer any specific
questions.

~~~
Jamesbaxter29
What books do you recommend do a university student without much familiarity
in the subject looking for practical design advice?

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george_kaplan
Not OP, but I can recommend these two books:

"Making Small Farms Work" by Richard Perkins

and

"Restoration Agriculture: Real World Permaculture for Farmers" by Mark Shepard

Then there are the books by Bill Mollison that arguably started it all:
"Permaculture: A Designers' Manual", and "Introduction to Permaculture"

~~~
adreamingsoul
These are great! Thank you, for sharing.

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Rubinsalamander
Rises the question which temperature is the "right" one. Assuming we can
control climate change at some point in the future

Like having a clima-council which votes to lower or rise the temperature.
Would definetly cause conflicts between very hot and cold nations

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api_or_ipa
The economic consequences would be absolutely huge. Take my native Canada for
an example. There's breathtaking amounts of land that's currently of little
economic value because of a shortened growing season and permafrost. A small
increase in temperature would have a huge impact on the usability of that
land. Conversely, other places in the world would suffer desertification and
suffer greatly.

As an amusing side-note I've pondered whether colder countries
could/should/will intentionally spew C02 into the atmosphere to improve their
own living situation. There's not a whole lot other countries could do about
it except try and capture the C02 which is much more expensive than burning
it. Obviously this doesn't take in effect other averse consequences from
global warming but it was still an amusing train of thought.

~~~
baxtr
BTW: it is CO2 not C02... (sorry)

~~~
api_or_ipa
Sorry that was me being lazy. On my dovark keyboard. C,0,2 are all right next
to each other on my right hand and since numbers are behind the shift key, my
left hand just holds the shift down. The alternative is a bit of a finger
juggle because my caps lock is remapped as well.

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andriesm
Geeze this conclusion seems rather counter intuitive, a much smaller human
population's pre-modern agriculture had enough of an impact on climate so much
as to prevent an ice age?

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paganel
Mainly because of deforestation (one of the causes mentioned in the article).
French Gaul in Roman times had already been largely deforested in the previous
centuries, some historians even suggest that the process had been underway
since Neolithic times, that’s about 4,000-5,000 years ago. It’s relatively
unconmplicated to get rid of large swaths of forrest without having to have
access to modern industrial tools, you just need to put some good old physical
work into it.

As a reference, I’m doing a mapping of Southern Romania’s forrests as they
showed up in a 1860s Austrian map (it’s a hobby project that I work on during
my spare time) and it’s crazy when comparing it to more modern times. As early
as the 1920s (that is in less than 60 years) 60-to-80% of the forrests from
the plane areas had disappeared, and that was not because of the introduction
of modern technology, because most of the tree-cutting was being done with
good old axes, but only because Romania had entered the international
agricultural markets and that land was more economically valuable with grain
or cows on it compared to trees (the same thing is now happening in Brazil).

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jaclaz
Sure, but the study places the "pivot point" much back in time in the 7,000 to
5,000 years ago range (probably give or take a thousand years):

>"I noticed that methane concentrations started decreasing about 10,000 years
ago and then reversed direction 5,000 years ago and I also noted that carbon
dioxide also started decreasing around 10,000 years ago and then reversed
direction about 7,000 years ago," says Ruddiman. "It alerted me that there was
something strange about this interglaciation ... the only explanation I could
come up with is early agriculture, which put greenhouse gases into the
atmosphere and that was the start of it all."

~~~
paganel
Yeah, I had noticed that, too. To give a totally unsubstantiated opinion (i.e.
mine) I'd say that that only helps make the case for the massive deforestation
happening as soon as the Neolithic Revolution got under way in earnest,
starting about 5,000 BCE, that would explain the rise in CO2 concentration
(also see the Cucuteni–Trypillia culture -
[https://en.wikipedia.org/wiki/Cucuteni%E2%80%93Trypillia_cul...](https://en.wikipedia.org/wiki/Cucuteni%E2%80%93Trypillia_culture)).
The rise in methane concentration which happened 2,000 years after that might
be explained by people raising a lot more cows around 3,000 BCE (the start of
"civilization" on the Nile and Euphrates, for example).

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coldtea
If indeed ancient farmers (that were like 1/100 our population) already had
"profoundly changed Earth's climate", so much for the "human activity couldn't
be the reason for climate change today" argument...

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empath75
nobody making those arguments is making them in good faith and no amount of
evidence will stop them from making it.

~~~
coldtea
Bad faith means not believing what you say ("with the intention of deceiving
someone or doing harm").

One could very well imagine (and some of us actually know) people that
legitimately believe that the climate change we're through is not man made --
they say it cause they believe it, they don't try to knowingly deceive anyone.

It's another thing to say something because you do not trust scientists
(including scientific consensus) because e.g. you believe that they
extrapolate from incomplete data and not enough understanding, or to prefer
this or that fringe researcher to the majority opinion, and another to be in
bad faith.

~~~
specialist
I now believe, but cannot prove, that most people's professed beliefs are not
rational, logical, reality-based, sensical.

Rather, beliefs appear to be more about identity, virtue signaling, and tribal
acceptance.

If true, reason is impotent. To change belief systems, one must use
psychology, rhetoric, propaganda, evangelism.

The lesswrong.com crowd is calling this "belief as attire". I don't know what
to call "Popperian beliefs" (true until proven false) vs "aspirational
beliefs" (make our own reality).

My greatest fear is that my self-image of being a Popperian is actually just
aspirational.

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jajag
As mentioned in the article, one of the interesting things about this is that
it provides support for an earlier date for the start of the anthropocene, as
opposed to a date in e.g. the 50s.

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edoo
The end of glaciers also opened up huge swaths of land to methane producing
life. Large percentages of the earths habitable land.

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pdonis
A glaring omission in this study is the effect of farming (and human
activities more generally) on land use and albedo.

