
4.2 Kiloyear Event - smacktoward
https://en.wikipedia.org/wiki/4.2_kiloyear_event
======
flixic
Naming things is hard.

Current name is relative to current date because it talks about an event 4200
years ago. Any literature discussing this will be stuck with this relative
name and eventually will become incorrect.

I understand why they don't want to use BC to name a global event that touched
all cultures, and far before C was a thing.

Maybe it would make sense to adopt kurzgesagt's Human Era calendar, starting
at approximate time of first human settlements. They call current year 12019.

~~~
lifthrasiir
Not exactly. A word "BP" in the full name ("4.2-kiloyear BP event") is a key:
it stands for "Before Present", where the "Present" is defined as 1 Jan 1950
for the archaeological and geological purpose [1].

[1]
[https://en.wikipedia.org/wiki/Before_Present](https://en.wikipedia.org/wiki/Before_Present)

~~~
ageofwant
So BP = C + 1950, and this is better how ? Seems worse really, why not just
stick with C ?

~~~
lifthrasiir
BP specifically means that the date was calibrated [1] after radiocarbon
dating. It is not just an epoch difference.

Also, the radiocarbon dating itself (and thus the beginning of effective
absolute dating) was invented around 1950, and nuclear weapon tests made
everything after that point unsuitable for the radiocarbon dating. It would be
natural to have that point as a reference for the "present" at least for now.

[1]
[https://en.wikipedia.org/wiki/Radiocarbon_calibration](https://en.wikipedia.org/wiki/Radiocarbon_calibration)

~~~
baddox
I actually never thought about the fact that human nuclear testing would
basically destroy the accuracy of radiocarbon dating. Any distant future
civilizations who assumed there had never been any ancient sources of
distortion would end up with results that are way off. Of course, that’s true
of us as well.

~~~
lifthrasiir
Technically we are still able to use radiocarbon dating for dates after 1950,
at the reduced accuracy though. This is what I meant by "unusable", because
other dating techniques will work better.

The calibration is there because the global 14C/12C ratio is not constant over
the time, and the same procedure can be used given the recent history of
ratios (that we do have). As far as I know, though, resulting error bars might
be much larger than usual because the function from uncalibrated ("14C") years
to calendar years is no more regular. For example see [1] where uncalibrated
t2 and t3 can correspond to much larger periods than t1's; historically this
happened only locally, but after 1950 it would be far more common. Still the
radiocarbon dating can be used with this caveat [2].

[1]
[https://commons.wikimedia.org/wiki/File:Variations_in_calibr...](https://commons.wikimedia.org/wiki/File:Variations_in_calibration_results.png)

[2]
[https://www.nytimes.com/2011/03/29/science/29qna.html](https://www.nytimes.com/2011/03/29/science/29qna.html)

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MichaelMoser123
[https://en.m.wikipedia.org/wiki/List_of_periods_and_events_i...](https://en.m.wikipedia.org/wiki/List_of_periods_and_events_in_climate_history)
'List of periods and events in climate history'

~~~
cbanek
I love learning about past Earth climate history and just history in general.
One of my mind blowing climate events is:

[https://en.wikipedia.org/wiki/Messinian_salinity_crisis](https://en.wikipedia.org/wiki/Messinian_salinity_crisis)

It's not in the list you link, but it's a pretty neat read. Basically, the
Mediterranean dried up and refilled about 6 million years ago.

~~~
mkl
And it's _five kilometres deep_.

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SideburnsOfDoom
What is the likely cause of this event?

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g3orge
I love reading these kinds of wikipedia articles especially when it comes to
reprecussions on ancient civilizations.. anyone got a book suggestion for s/t
more detailed?

~~~
pramsey
Best book on the subject I read is Wright's "A Short History of Progress"
[https://www.amazon.com/Short-History-Progress-Ronald-
Wright/...](https://www.amazon.com/Short-History-Progress-Ronald-
Wright/dp/0786715472) Jared Diamond's "Collapse" is in a similar vein, but
less cleanly written.

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pts_
Funny I just read this [https://m.timesofindia.com/india/two-major-floods-
wiped-out-...](https://m.timesofindia.com/india/two-major-floods-wiped-out-
several-medieval-indian-dynasties-study/articleshow/72716607.cms)

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phkahler
What will this be called in 100 years?

~~~
ithkuil
"Because the present changes every year, archaeologists, by convention, use
A.D. 1950 as their reference. "

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inspirel
Climate change over time.

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travisoneill1
The chart in the article makes recent man made global warming look
insignificant compared to recent changes. Much different than the often sited
xkcd, [https://xkcd.com/1732/](https://xkcd.com/1732/), which shows the same
time period as basically a flat line. Who is right?

~~~
ffellow
All the events in the wikipedia articles are localized, whereas the current
global warming is a a global event, which is what is referenced by xkcd.

What this means is that the frequency and/or the intensity of these local
outlier events can increase significantly. This is what man-made climate
change means and we can still avoid most of the negative effects if we want
to.

Often these local climate change events are taken as proof that 'climate has
always changed'. Well, yes of course - but not on a global scale during human
civilization as we know it.

Personally, imagining these events occuring during our lifetime, maybe several
at once or just a couple of decades apart scares the crap out of me.

~~~
perl4ever
"we can still avoid most of the negative effects if we want to"

There is (possibly a minority) view that no, we can't, and things are far, far
worse than people think. That contrary to the idea that people exaggerate the
threat, in fact it's been minimized to the point where we are about as
prepared for it as we would be for a large asteroid strike.

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Analyticss
Climate change over time. Earth actually experienced more than '4.2 Kiloyear
Event'.

1.「4.2 Kiloyear event」 - A severe aridification event, occurring around 2200
B.C., that greatly contributed to the fall of the Akkadian empire.

2.「Medieval Warming Period」 - A warmer climate experienced especially in the
Northern Hemisphere when Vikings and Inuit were moving to Greenland, around
800-1300 A.D.

3.「Little Ice Age」 - A cooler climate that eventually caused the demise of the
Vikings, lasting from circa 1300-1850 A.D.

4.「The Holocene Era」 - Starting about 10,000 years ago, this era includes the
Medieval Warming Period, the Little Ice Age, and continues all the way up
until today!

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sillysaurusx
Seems like evidence that our current climate change might be random.

How do you rule out random climate variation scientifically? I'm curious, do
we have enough data to say one way or the other?

I'm hesitant to post this, since it seems like detached scientific
conversation about climate change has been in short supply. But perhaps.

~~~
bloudermilk
The warming of our atmosphere is easily predicted by basic science related to
greenhouse gasses and solar radiation.

This isn't disputable as randomness any more than an object can be said to
have randomly fallen to the ground when dropped.

Here is one of countless sources you can find that explain this principle and
the consequences: [https://www.climate.gov/news-features/understanding-
climate/...](https://www.climate.gov/news-features/understanding-
climate/climate-change-atmospheric-carbon-dioxide)

~~~
thepangolino
>In fact, the last time the atmospheric CO2 amounts were this high was more
than 3 million years ago, when temperature was 2°–3°C (3.6°–5.4°F) higher than
during the pre-industrial era, and sea level was 15–25 meters (50–80 feet)
higher than today.

Doesn't this mean that the correlation between CO2 levels and temperatures
isn't that big?

~~~
afthonos
I can come up with a couple alternatives to your explanation:

1\. Our current carbon levels haven’t been high long enough for their total
effects in temperature to be felt yet, given the size of the system they must
affect. 50 years is a blip on geological timescales.

2\. There are cascading effects to high CO2 levels that will take longer to
manifest themselves and which will raises the temperatures further. Permafrost
melting and releasing methane is a possible example.

~~~
ImaCake
The orbit of the earth around the sun, and the activity of the sun itself are
also possible culprits. I'm sure actual climatologists have a better
explanation.

