
America colonisation ‘cooled Earth's climate’ - Tomte
https://www.bbc.com/news/science-environment-47063973
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pdonis
The article says the scientists estimate the CO2 reduction due to population
decline as 7 to 10 ppm. Yet they claim this caused the Little Ice Age. That
doesn't seem justified; that small a CO2 change doesn't have that much of an
impact even on the highest estimates of climate sensitivity (and those highest
estimates are known to be too high anyway). For comparison, the CO2 change
since the start of the industrial revolution is about 130 ppm.

~~~
codesushi42
Agreed. The indigenous peoples were not burning fossil fuels either. This
signal is pretty weak. The same could be claimed about the Black Death that
ravaged Europe.

~~~
pdonis
_> The indigenous peoples were not burning fossil fuels either._

They were changing the use of the land, though. The hypothesis appears to be
that the land that had been cultivated reverted back to forest, which meant
more trees and hence more CO2 uptake. (Though even that could be questioned,
since crops also take up CO2, and growing new crops every year might well take
up more CO2 than a forest of trees that just grow once and then stay there.)

~~~
bryanlarsen
Crops get eaten and their straw rots, releasing the CO2 they've sequestered.
That happens with trees too, but less completely and over a much larger time
scale.

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TimTheTinker
Note this isn't a guilt trip about the English and French colonies in North
America, though the title might seem to imply that.

The major bloodbaths took place further south with the overthrow and slaughter
of the Inca and Aztec empires -- with populations of 12 million and 5 million,
respectively.

~~~
wutbrodo
The article isn't even focusing on that, AFAICT.

> 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 only thing that was that early, that rapid, and that devastating was the
diseases introduced by early European visitors that preceded their
colonization by decades and leagues.

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swalsh
Question, beacause i'm not familiar enough with how trees "suck" co2 out of
the air. This study is saying it would take something like 100 forests the
size of France to solve the climate change problem by tree growth alone. Would
it be possible to genetically modify a tree to consume C02 100x more than a
regular tree so we would only need 1 france of mutated trees?

~~~
Symmetry
What would be really nice to invent is some superior alternative to existing
photosynthesis that can better convert sunlight, water, and CO2 into organic
matter than existing plants can. Once you've got that it might not matter
whether they plants are trees or algae, so long as the organic matter can be
buried.

~~~
zeristor
They're looking at GMing Nitrogenase into plants so that they're no longer
limted by the lack of Nitrogen, they're also working on copying C4
photosynthesis into C3 photosynthesis plants so they can more efficiently use
CO2.

A superior form of photosynthesis isn't easy to imagine, the one we've got
seems to use nifty quantum effects to be very efficient, I think about 80%.

Earth cycles carbon, there's been a few spells when it has run out of carbon
and turned it a snowball, seemingly saved by carbonate rocks being recycled by
volcanoes.

I think there'll run out of phosphate before then though.

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

I've been hearing about this as if it's a new label for about 15 years now. I
was pretty certain we've already accepted this term and generally accept it's
a very clear, measurable geologic epoch.

~~~
gaborbodoky
I know just of antropocentrism. Is there a difference? Anyway this climatical
way to look at colonisation is totally new to me. Interesting article!

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RickJWagner
I'd like to know how they made the population estimates. It just seems like a
difficult thing to do.

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milsorgen
Hardly a well accepted account of that cooling period but I suppose laying the
blame on Europeans and their offshoots is quite in vogue these days.

~~~
dang
Could you please stop posting ideological flamebait to HN? It leads to
ideological flamewar, which is just what we're trying to avoid, and you've
unfortunately been doing it repeatedly.

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

