did climate change start in the neolithic ?

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bicicleur 2

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Millennia ago, ancient farmers cleared land to plant wheat and maize, potatoes and squash. They flooded fields to grow rice. They began to raise livestock. And unknowingly, they may have been fundamentally altering the climate of Earth.


Fifteen years ago, study co-author William Ruddiman, emeritus paleoclimatologist at the University of Virginia, was studying methane and carbon dioxide trapped in Antarctic ice going back tens of thousands of years when he observed something unusual.

"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."



https://archaeologynewsnetwork.blog...red-us-from-glaciers.html#jY3PPkmt0KDdJ17Q.97
 
Why would you assume that climate change started in the Neolithic?

What brought about the Ice Ages? That isn't climate change? There was certainly no Neolithic and no farming before then.

I think you need to look at the history of the earth through a deeper lens.

Climate Change 101:
https://skepticalscience.com/climate-change-little-ice-age-medieval-warm-period.htm

"Climate is always changing. We have had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and there have been previous periods that appear to have been warmer than the present despite CO2 levels being lower than they are now."
 
It is a theory, nothing more.
But concentrations of CO2 and CH4 changing are a hint.

I know climate is unstable. It will always change.
The question is, has human activity an impact on climate, and if so, since when?

Last 800.000 years there has been an LGM about every 100.000 years, followed by a warmer period.
Now we are already 20.000 years in the warmer period, which is quite long.
During the warm period before this one, some 120.000 years ago, sea levels rose till about 2 meters higher than today.
Just to put things in perspective ..
 
P.S.

Angela, the link you provide is biassed.
Climate is very complex. Those who claim to know the truth are all biassed. And there are so many of them ..
 
bicicleur said:
P.S.

Angela, the link you provide is biassed.
Climate is very complex. Those who claim to know the truth are all biassed. And there are so many of them ..
Click to expand...

Yes. Talking about climate change and putting a link to SS is like talking about politics and putting links to Hufpost, Msnbc or Fox.
 
Bicicleur,
And yes. Anthropogenic climate change has started in the Neolithic. Whatever meager it was, agriculture did change climate locally.
Removing a part of a forest and replace by agriculture does have an impact on local climate (mostly min/max at night).
 
So this encouraged you to doubt Al Gore and Prince Charles after they have made Billions with their Borneo plantations selling carbon tax credits to European companies? Congratulations. Better late than never.

bicicleur said:
Millennia ago, ancient farmers cleared land to plant wheat and maize, potatoes and squash. They flooded fields to grow rice. They began to raise livestock. And unknowingly, they may have been fundamentally altering the climate of Earth.


Fifteen years ago, study co-author William Ruddiman, emeritus paleoclimatologist at the University of Virginia, was studying methane and carbon dioxide trapped in Antarctic ice going back tens of thousands of years when he observed something unusual.

"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."



https://archaeologynewsnetwork.blog...red-us-from-glaciers.html#jY3PPkmt0KDdJ17Q.97
Click to expand...
 
Both deforestation and reforestation have climatic effects (increasing and decreasing CO2) .
 
CrazyDonkey said:
Both deforestation and reforestation have climatic effects (increasing and decreasing CO2) .
Click to expand...
How much climate one million of neolithic farmers could change, when we have couple of billions of farmers now (which is a thousand times more), and yet most of global warming is blamed on CO2 emission from fossil fuels, and not by farming per se. Having this perspective one would conclude that neolithic farming effect on climate was imperceivable.
 
LeBrok said:
How much climate one million of neolithic farmers could change, when we have couple of billions of farmers now (which is a thousand times more), and yet most of global warming is blamed on CO2 emission from fossil fuels, and not by farming per se. Having this perspective one would conclude that neolithic farming effect on climate was imperceivable.
Click to expand...

Slash and burn:

Now Ruddiman in a paper published in Quaternary Science Reviews is answering another criticism of his theory that says human populations were too small to cause as much deforestation for food production as Ruddiman has suggested. According to Ruddiman, human populations may have been small, but they were hugely destructive when it came to the world’s forests. He says that contemporary civilization uses 90 percent less land per person for growing food than the farmers of 7,000 years ago.

“They used more land for farming because they had little incentive to maximize yield from less land, and because there was plenty of forest to burn,” said Ruddiman. “They may have inadvertently altered the climate.”

Due to the large amount of forested land, Ruddiman argues, that farmers used a rotation method for agriculture: once early farmers saw yields decline in one area they would simply burn more forest and begin planting in new fields. This could have led to a situation where five times more land was deforested than was actually farmed at any given time.

“It was only as our populations grew larger over thousands of years, and needed more food, that we improved farming technologies enough to begin using less land for more yield,” Ruddiman said.
Click to expand...

https://news.mongabay.com/2009/08/d...e-altered-climate-long-before-industrial-era/
 
LeBrok said:
We read:

“They may have inadvertently altered the climate.”

You see, it is a guess, not firm numbers. Other words, it is unproven hypothesis. All it is.
Click to expand...

It's a theory. That doesn't mean there isn't evidence to support it. What kind and how much is the question.

Reforestation after retreat of the glaciers pulled carbon out of the atmosphere, moderating the temperature change. If there was widespread deforestation due to slash-and-burn agriculture, that would add CO2, methane, and other greenhouse gases to the atmosphere, heating up the climate. Wide-scale herding might also have had an effect, apart from conversion of forest to pasture - each cow releases 70 to 150 kg of methane a year.
 
CrazyDonkey said:
It's a theory. That doesn't mean there isn't evidence to support it. What kind and how much is the question.

Reforestation after retreat of the glaciers pulled carbon out of the atmosphere, moderating the temperature change. If there was widespread deforestation due to slash-and-burn agriculture, that would add CO2, methane, and other greenhouse gases to the atmosphere, heating up the climate. Wide-scale herding might also have had an effect, apart from conversion of forest to pasture - each cow releases 70 to 150 kg of methane a year.
Click to expand...
Could you entertain evidence please.
 
CrazyDonkey said:
It's a theory. That doesn't mean there isn't evidence to support it. What kind and how much is the question.

Reforestation after retreat of the glaciers pulled carbon out of the atmosphere, moderating the temperature change. If there was widespread deforestation due to slash-and-burn agriculture, that would add CO2, methane, and other greenhouse gases to the atmosphere, heating up the climate. Wide-scale herding might also have had an effect, apart from conversion of forest to pasture - each cow releases 70 to 150 kg of methane a year.
Click to expand...
Could you entertain evidence please.

Global temps of last 10k years can't confirm it.
gisp-last-10000-new.png
 
LeBrok said:
Could you entertain evidence please.

Global temps of last 10k years can't confirm it.
gisp-last-10000-new.png
Click to expand...

Your chart ends in 1855!!!!

Here's a more representative one, with modern temperatures:

sg2wav.jpg

The temperature peaks:

1) ~7,000 (5,000 BCE): Post-glacial warm period due to decreased reflection off ice sheets and methane releases from melting permafrost. Reforestation across the northern temperate zone likely contributed to the following deep dip ("8.2 kiloyear event") from 5,000 to 4,000 BCE.

2) ~5,800 (3,800 BCE): Corresponds to the expansion of early agriculture into Europe and Asia, with the expansion of farming causing deforestation. Interrupted by a sharp dip ("Piora oscillaion") at ~5,200 (3,200 BC), which some attribute to vulcanism - associated with the domestication of the horse in central Asia.

3) ~5,000 (3,000 BC): Rise of the major agricultural civilizations. Followed by a cold period, but with warming temperatures, beginning around ~4,800 (2,800 BC) and peaking at:

4) ~3,800 (1,800 BCE), the approximate date of the Santorini volcano (Plato's "Atlantis"?), leading to the decline of the Minoan Empire and the Hyksos invasion of Egypt, with a following sharp dip at ~3,500 (1,500 BCE), possibly precipitating the collapse of the Bronze Age (and the Harappan Empire in India), followed by a recovery and then a deeper dip covering the Greek "Dark Ages" (population collapse and reforestation).

This roughly fits the thesis laid down here:

The hypothesis advanced here is that the Anthropocene actually began thousands of years ago as a result of the discovery of agriculture and subsequent technological innovations in the practice of farming. This alternate view draws on two lines of evidence. First, the orbitally controlled variations in CO2 and CH4 concentrations that had previously prevailed for several hundred thousand years fail to explain the anomalous gas trends that developed in the middle and late Holocene.

Second, evidence from palynology, archeology, geology, history, and cultural anthropology shows that human alterations of Eurasian landscapes began at a small scale during the late stone age 8000 to 6000 years ago and then grew much larger during the subsequent bronze and iron ages. The initiation and intensification of these human impacts coincide with, and provide a plausible explanation for, the divergence of the ice-core CO2 and CH4 concentrations from the natural trends predicted by Earth-orbital changes.
Click to expand...

https://stephenschneider.stanford.edu/Publications/PDF_Papers/Ruddiman2003.pdf
 
I don't see how that sharp spike in temperature after 1855 (and after the huge decline from medieval onward) can be blamed on Neolithic farmers who died several thousands of years before then.

also the number of farmers only went higher as time went on. You would expect temps to continue to rise between the first farmers and more modern periods like the Roman, correct?
 
davef said:
I don't see how that sharp spike in temperature after 1855 (and after the huge decline from medieval onward) can be blamed on Neolithic farmers who died several thousands of years before then.

also the number of farmers only went higher as time went on. You would expect temps to continue to rise between the first farmers and more modern periods like the Roman, correct?
Click to expand...

No one is claiming that early agricultural practices (slash and burn) caused modern atmospheric warming (post-1855), just that they might have, along with deforestation, through the conversion of forest land to fields and pasture, helped trigger earlier warm periods. In either case, the mechanism is the same - higher temperatures follow higher CO2 levels.

On your second point, I already posted this once, but will post it again:

Now Ruddiman in a paper published in Quaternary Science Reviews is answering another criticism of his theory that says human populations were too small to cause as much deforestation for food production as Ruddiman has suggested. According to Ruddiman, human populations may have been small, but they were hugely destructive when it came to the world’s forests. He says that contemporary civilization uses 90 percent less land per person for growing food than the farmers of 7,000 years ago.

“They used more land for farming because they had little incentive to maximize yield from less land, and because there was plenty of forest to burn,” said Ruddiman. “They may have inadvertently altered the climate.”

Due to the large amount of forested land, Ruddiman argues, that farmers used a rotation method for agriculture: once early farmers saw yields decline in one area they would simply burn more forest and begin planting in new fields. This could have led to a situation where five times more land was deforested than was actually farmed at any given time.

“It was only as our populations grew larger over thousands of years, and needed more food, that we improved farming technologies enough to begin using less land for more yield,” Ruddiman said.
Click to expand...

https://news.mongabay.com/2009/08/d...e-altered-climate-long-before-industrial-era/
 
CrazyDonkey said:
Your chart ends in 1855!!!!

Here's a more representative one, with modern temperatures:

sg2wav.jpg

The temperature peaks:

1) ~7,000 (5,000 BCE): Post-glacial warm period due to decreased reflection off ice sheets and methane releases from melting permafrost. Reforestation across the northern temperate zone likely contributed to the following deep dip ("8.2 kiloyear event") from 5,000 to 4,000 BCE.

2) ~5,800 (3,800 BCE): Corresponds to the expansion of early agriculture into Europe and Asia, with the expansion of farming causing deforestation. Interrupted by a sharp dip ("Piora oscillaion") at ~5,200 (3,200 BC), which some attribute to vulcanism - associated with the domestication of the horse in central Asia.

3) ~5,000 (3,000 BC): Rise of the major agricultural civilizations. Followed by a cold period, but with warming temperatures, beginning around ~4,800 (2,800 BC) and peaking at:

4) ~3,800 (1,800 BCE), the approximate date of the Santorini volcano (Plato's "Atlantis"?), leading to the decline of the Minoan Empire and the Hyksos invasion of Egypt, with a following sharp dip at ~3,500 (1,500 BCE), possibly precipitating the collapse of the Bronze Age (and the Harappan Empire in India), followed by a recovery and then a deeper dip covering the Greek "Dark Ages" (population collapse and reforestation).

This roughly fits the thesis laid down here:



https://stephenschneider.stanford.edu/Publications/PDF_Papers/Ruddiman2003.pdf
Click to expand...

Oh, the peaks! You mean that neolithic agriculture existed only for few years around 6k and 5k BC, disappearing during temperature declines? But wait, there were no farmers in Europe at 8k years ago when the peak was the highest or in both Americas and barely anything in India either. Just some pre pottery farming in Middle East and China. As you see, very limited slash and burn to small area of our planet. On top of it from Bronze Age till 19 hundreds, when agriculture grew much bigger and way more intense, from feeding 10 million people to 1 billion, we see continues downtrend in temps.
Brilliant deduction, dude!
 
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