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Utopia Talk / Politics / White men responsible for ice age, too!!
Victim
Member
Fri Feb 01 16:45:58
You're always changing the climate back and forth, stop it!

http://www.bbc.com/news/science-environment-47063973

America colonisation ‘cooled Earth's climate’
By Jonathan Amos BBC Science Correspondent

31 January 2019


Colonisation of the Americas at the end of the 15th Century killed so many people, it disturbed Earth's climate.

That's the conclusion of scientists from University College London, UK.

The team says the disruption that followed European settlement led to a huge swathe of abandoned agricultural land being reclaimed by fast-growing trees and other vegetation.

This pulled down enough carbon dioxide (CO₂) from the atmosphere to eventually chill the planet.

It's a cooling period often referred to in the history books as the "Little Ice Age" - a time when winters in Europe would see the Thames in London regularly freeze over.

"The Great Dying of the Indigenous Peoples of the Americas led to the abandonment of enough cleared land that the resulting terrestrial carbon uptake had a detectable impact on both atmospheric CO₂ and global surface air temperatures," Alexander Koch and colleagues write in their paper published in Quaternary Science Reviews.



What does the study show?

The team reviewed all the population data it could find on how many people were living in the Americas prior to first contact with Europeans in 1492.

It then assessed how the numbers changed in following decades as the continents were ravaged by introduced disease (smallpox, measles, etc), warfare, slavery and societal collapse.

It's the UCL group's estimate that 60 million people were living across the Americas at the end of the 15th Century (about 10% of the world's total population), and that this was reduced to just five or six million within a hundred years.

The scientists calculated how much land previously cultivated by indigenous civilisations would have fallen into disuse, and what the impact would be if this ground was then repossessed by forest and savannah.

The area is in the order of 56 million hectares, close in size to a modern country like France.

This scale of regrowth is figured to have drawn down sufficient CO₂ that the concentration of the gas in the atmosphere eventually fell by 7-10ppm (that is 7-10 molecules of CO₂ in every one million molecules in the air).

"To put that in the modern context - we basically burn (fossil fuels) and produce about 3ppm per year. So, we're talking a large amount of carbon that's being sucked out of the atmosphere," explained co-author Prof Mark Maslin.

"There is a marked cooling around that time (1500s/1600s) which is called the Little Ice Age, and what's interesting is that we can see natural processes giving a little bit of cooling, but actually to get the full cooling - double the natural processes - you have to have this genocide-generated drop in CO₂."



Where's the support for the connection?

The drop in CO₂ at the time of the Great Dying is evident in the ice core records from Antarctica.

Air bubbles trapped in these frozen samples show a fall in their concentration of carbon dioxide.

The atomic composition of the gas also suggests strongly that the decline is being driven by land processes somewhere on Earth.

In addition, the UCL team says the story fits with the records of charcoal and pollen deposits in the Americas.

These show the sort of perturbation expected from a decline in the use of fire to manage land, and a big grow-back of natural vegetation.

Ed Hawkins, professor of climate science at Reading University, was not involved in the study. He commented: "Scientists understand that the so-called Little Ice Age was caused by several factors - a drop in atmospheric carbon dioxide levels, a series of large volcanic eruptions, changes in land use and a temporary decline in solar activity.

"This new study demonstrates that the drop in CO₂ is itself partly due the settlement of the Americas and resulting collapse of the indigenous population, allowing regrowth of natural vegetation. It demonstrates that human activities affected the climate well before the industrial revolution began."
Are there lessons for modern climate policy?

Co-author Dr Chris Brierley believes there is. He said the fall-out from the terrible population crash and re-wilding of the Americas illustrated the challenge faced by some global warming solutions.

"There is a lot of talk around 'negative emissions' approaches and using tree-planting to take CO₂ out of the atmosphere to mitigate climate change," he told BBC News.

"And what we see from this study is the scale of what's required, because the Great Dying resulted in an area the size of France being reforested and that gave us only a few ppm. This is useful; it shows us what reforestation can do. But at the same, that kind of reduction is worth perhaps just two years of fossil fuel emissions at the present rate."

The study also has a bearing on discussions about the creation of a new label to describe humanity's time - and impacts - on Earth.

This epoch would be called the Anthropocene, and there is currently a lively debate over how it should be recognised in the geological record.

Some researchers say it would be most obvious in deposits that record the great acceleration in industrial activity from the 1950s onwards.

But the UCL team argues that the Great Dying in the Americas shows there are significant human interactions that left a deep and indelible mark on the planet long before the mid-20th Century.
Sam Adams
Member
Fri Feb 01 16:48:02
Lol.

Seb believes this.
Rugian
Member
Fri Feb 01 16:50:20
What's the journalist equivalent of clickbait bullshit?

Because this article is definitely that. 90% population decline by 1592, blow me.
Rugian
Member
Fri Feb 01 16:56:15
I mean, the premise alone should have rendered it dead on arrival. We have no idea what the pre-Columbian population of the Americas actually was, so it's by definition impossible to extrapolate any data from there.

A scholar with any sort of integrity would nev were r have had this published.
Sam Adams
Member
Fri Feb 01 17:47:13
Ya, and then they try to calculate the temperature then(unlikely to be accurate to what they want) AND then feed it into a low resolution climate model missing all sorts of important data, and get an answer precise to +-20%?

Lol. This is alabama-seb levels of stupidity here.
Dukhat
Member
Fri Feb 01 18:08:01
Sam Adams laying down scientific truth from his mom's basement ... oh wait.
Sam Adams
Member
Fri Feb 01 18:09:36
Not to mention their biomass per hectare estimate is too high, their cleared land per stone age person is way too high, and their estimate of temperature impact per unit co2 is too high.

Pure trash. Who published this shit?
Sam Adams
Member
Fri Feb 01 18:10:29
Cuckhat is like "how many meters is there in a kilometer?"
Sam Adams
Member
Fri Feb 01 18:11:56
"University College London, UK."


Lol that figures. Seb science. Almost as bad as cuckhat science.
jergul
large member
Fri Feb 01 18:16:59
Sammy
The CO2 decrease is known from glacial core samples.

The question is then what caused the CO2 decrease?

Dukhat
Member
Fri Feb 01 18:27:34
You wouldn't even last 3 seconds in an elementary school debate much less a college setting. What's amazing is that Sam claims to have a graduate degree.

LOL, fucking lying retard.
Sam Adams
Member
Fri Feb 01 18:28:11

"The question is then what caused the CO2 decrease? "

Not regrown farmland in mesoamerica. Youd be hard pressed to get a single ppm co2 out of that. 0.1 ppm is more likely.
Sam Adams
Member
Fri Feb 01 18:29:24
Lol cuckhat go away. Your mind is so weak your presence provides no value.
Dukhat
Member
Fri Feb 01 18:32:25
I happen to think it's a really bad study too but none of the reasons you provided are any good.

For one the little ice age began around the 1300's and there are way too many other mitigating factors around the time too for trees around the size of France to be that important.

Pillz
Member
Fri Feb 01 19:02:12
Cuckhat is so dumb

Can he read?
Dukhat
Member
Fri Feb 01 19:33:02
The conclusion is still sound. We need to massively depopulate the earth. Cuckservatives doing their part by living the life of an incel.
Wrath of Orion
Member
Sat Feb 02 05:28:53
This is (at least currently) an open access article.

http://www.../article/pii/S0277379118307261

I would start there before continuing any debate.
jergul
large member
Sat Feb 02 06:04:49
Yah, like I said, the problem is balancing known CO2 changes. What the hell happened to decrease recorded CO2 levels (those are known from glacial core samples)?

If I were to nitpick, I would say that the focus is too narrow. Old forest regrowth takes about 800 years (complete cycles of growth has to die-off to give the preconditions for old forest recovery).

In my mind, something happened earlier that fundamentally changed human land use, then the Americas happened, then something happened that suddenly began to increase C02 production again.

1349, then 1500ds, then industrial revolution.

Compounded by temperature decreases that rendered a lot of previously used land unsuitable for agriculture (compensated for by more intensive land use made possible by new produce from the Americas. Potato anyone?).

So more complex. But the basis claim is credible (die-off in the Americas helps explain why CO2 levels fell).
Sam Adams
Member
Sat Feb 02 11:24:43
A single good growing year in a large basin(IE amazon or africa), the result of luck/random variation, would take much more co2 out of the atmosphere than the collapse of mesoamerica. Keep in mind that a high stone age civ could not have cleared much land, and their conquerors would still have cleared some of this land too, and the biomass loading of much of their area is not high.

The paper, thanks for the raw link woo, overestimates many things. Its a little better than the news article but its still a pretty shitty paper.
Sam Adams
Member
Sat Feb 02 11:27:27
I estimate 0.1 ppm for the downfall of the 3 high stone age mesoamerican civs. Perhaps as high as 1.0.
jergul
large member
Sat Feb 02 13:09:27
http://new...tion-satellite-computer-model/

Speaking of the Amazonian basin.

"Chouin's own paper introduces the plague hypothesis and centers on his archaeological excavation work on sites from the 12th to 15th centuries in West Africa. There, he also found evidence of the abandonment of settlements during the 14th century.

"So that's another set of evidence, coming this time from the tropical forest belt, very far away from the Sahel, which strengthens once again this hypothesis that yes, indeed, something major happened in the 14th century.""

Speaking of the African tropical forests.

=========

I think we can conclude that reforestation on land previously used by humans is the primary cause of decreased CO2. The primary cause for that is at least 2 horsemen of the apocalypse. Probably all 3.

1350-1650 would be the primary time frame.

Yay.
Sam Adams
Member
Sun Feb 03 10:46:38
"I think we can conclude that reforestation on land previously used by humans is the primary cause of decreased CO2."

false.

The human population in that timeframe was, on average, growing.

http://upl...growth_%28log-log_scale%29.png

There was no net reclamation of land AND even if there were, pre industrial humans were too puny to matter much.
jergul
large member
Sun Feb 03 11:28:37
Sammy
Population is not a proxy for land use. The period coincides the significant advances in agricultural productivity without any suggestion of improved living standards.

Plagues, conflict and starvation (caused by systemic crop failures on marginal, very labour intensive land) caused land to be abandoned and never farmed again.

You might do well to remember we are not speaking of huge reductions in CO2 levels.

Puny humans devastated mega-fauna and completely destroyed temperate forests in what is now Syria, Lebanon, Greece, the Adriatic area, Italy, Sicily, and Spain.
Sam Adams
Member
Sun Feb 03 13:35:15
"Population is not a proxy for land use"

Wrong.

"Puny humans devastated mega-fauna and completely destroyed temperate forests "

Still puny, compared with a planet's atmosphere.
jergul
large member
Sun Feb 03 14:07:50
Sammy
You are incorrect on proxy.

7-10 parts C02 per million is also puny, compared to the planet's 1 million parts per million atmosphere.
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