4.2 Kiloyear Event

https://en.wikipedia.org/wiki/4.2_kiloyear_event

by smacktoward • 7 years ago

136 94 7 years ago

en.wikipedia.org

https://en.m.wikipedia.org/wiki/List_of_periods_and_events_i... 'List of periods and events in climate history'

chrisco2556• 7 years ago

These are very interesting. They do not get covered very often, but these events show climate changes in precipitation and temperature occur on the regular and cause even dramatic events (like the drying of the Sahara) naturally. I'm still trying to piece together what impacts geomagnetic excursions and reversals have on climate. During the last reversal 780,000 years ago the winter Asian monsoon was about 3x stronger than today according to one study I read.

KnightOfWords2• 7 years ago

Historical civilisations were very vulnerable to changes in local climate as they were heavily reliant on local food production, whereas we routinely ship food across oceans. Events like the [Little Ice Age](https://en.wikipedia.org/wiki/Little_Ice_Age) barely show up in the global climate record.

Earth's climate has varied greatly over time but its the current rate of change that is so alarming. During the last ice age it was about 4.5 degrees colder but it took 10,000 years to reach modern temperatures. We're currently on a path to changes of that magnitude within the next 70-100 years.

cbanek• 7 years ago

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

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• 7 years ago

And it's five kilometres deep.

Symmetry• 7 years ago

One of the best XKCDs ever is sort of related:

https://www.explainxkcd.com/wiki/index.php/1190:_Time

flixic• 7 years ago

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.

lifthrasiir3• 7 years ago

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

senectus1• 7 years ago

I'd never heard of that before... I like it.

p1mrx• 7 years ago

So when Marty went back to 1955, that actually was The Future, archaeologically speaking.

ageofwant2• 7 years ago

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

Iv• 7 years ago

BP can be read as "Before Pollution by airborne radioactive isotopes made radiocarbon dating unusable"

LeifCarrotson• 7 years ago

Present being defined as 1950 strikes me as exactly the sort of problem that GP was trying to avoid.

Thorentis• 7 years ago

Why is BC bad because this event touches all cultures? Every part of science and academia is effected by the culture doing the research, and is almost its own fascinating historical record in itself. Trying to make everything as generic as possible is bland and boring.

squiggleblaz2• 7 years ago

The reason BC is bad is because, when you hear BC, you think, oh this has been calibrated by knowledge of the passage of time according to records by humans. So perhaps we know it happened in year 20 of the reign of King B, and we have enough other information to believe that means about 125 BC.

But the date of this event was determined by radioactive calibration. It's not measuring the same thing. It measures something that approximates human years.

This might seem like a trivial distinction to lay people, but it's relevant to the field, and the 4.2 k BP year event is a technical term.

thih9• 7 years ago

Trying to make everything as generic as possible is bland and boring.

This is subjective.

On the other hand going with a generic choice helps create a well defined universal language. This makes scientific cooperation across cultures easier.

Sample difficulties of going with culture-specific naming: https://en.m.wikipedia.org/wiki/Comparison_of_the_imperial_a...

cies• 7 years ago

Naming things is hard.
Maybe it would make sense to adopt kurzgesagt's Human Era calendar, starting at approximate time of first human settlements.

So what about calling it the settlement era, as humans were around before the first settlement, making "human era" a bad name to begin with. :)

sillysaurusx3• 7 years ago

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.

Numberwang• 7 years ago

In what way is this evidence against man made climate change?

sillysaurusx3• 7 years ago

Intense, world-changing climate change has been with us since long before fossil fuels. This is yet another instance.

I am interested in the scientific methodology that rules out such variations and confirms that fossil fuels are in fact responsible.

The time period is an obvious one: we seem to be seeing spikes in one century vs millennia. But the details of those spikes matter in comparison to our total historical record; hence the curiosity.

bloudermilk• 7 years ago

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/...

thepangolino• 7 years ago

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?

jen729w2• 7 years ago

For me – scientifically-minded layperson, but not a climate scientist – the issue seems to be that people have conflated & confused two issues. One: that the climate was, without argument, different in the past. Two: that we are now, without argument, influencing the climate due to the extraordinary amount of carbon dioxide that we are producing.

One does not preclude the other. Was the climate different, often hotter and drier, in the past? Sure. Evidence shows that it was.

But does that mean that we aren’t leading ourselves in to a short/medium-term catastrophe by dumping enormous amounts of CO2 in to the environment now? No. The two are unrelated.

Imagine if we determined that the climate was on a natural cycle, such that the entire Earth would warm, fires and droughts would become commonplace, and that sea levels would rise as a result of global temperature. Would we just do nothing? I’d hope not. I’d hope that it would spur us in to action, to realise that our quality of life is about to radically change, that human migration will necessarily increase, that people living near the sea, or depending on water, will have their lives irrevocably changed.

That has happened in the past. We just didn’t have such a complicated society at the time, so the impacts were less. If you count the extinction of the Egyptian society as “less”.

It’s also happening now, except we are doing it. Voluntarily, with full knowledge of the ultimate result.

That seems, to people like me, a bit silly.

perl4ever6• 7 years ago

Shouldn't the default assumption be that humans are affecting the climate and there is an underlying natural trend, and that adds significant uncertainty to the magnitude and sign of those two factors?

People always seem to talk as though it's one or the other, but it seems to me essentially impossible that it's not both.

nitrogen• 7 years ago

There are plenty of resources on the topic and prior discussions on HN. People really don't want to rehash them because 1. it gets boring and 2. it leads to flamewars.

You ask "do we have enough data". Well, the same data that gives us evidence of prior climate events is the same data that shows human emissions are climatologically significant. So if we have enough data to study random changes, we have enough to study the changes we are causing.

If you want to take a stance against man-made climate change, you'll actually need to do your own research first and have a really good reason why it's wrong. Can you yourself list all the data sources that go into climatology and why they aren't adequate?

sillysaurusx3• 7 years ago

I don't think I took a stance against anything. I think I asked a couple of questions.

I had a longer comment prepared, but as you say, responding to accusations tends to get boring.

If you want to have a conversation about this, though, it would be nice.

SideburnsOfDoom4• 7 years ago

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

To me, it seems like (strong) evidence that climate can change.

And that there is a cause of this change, and that the cause that can be found. Maybe volcanic, meteoric, related to vegetation levels, or other?

Which is, I think, the _opposite_ of random. It is understandable and predictable.

How do you rule out random climate variation scientifically?

Outside of quantum physics, "it was random" is not a scientific explanation. Science finds causes.

When applied to "our current climate change", the idea that climate can change and change a lot, in response to causes, well, that provides the opposite conclusion to yours doesn't it: we can see the causes this time.

chrisco2556• 7 years ago

It's not that it's random. It's that it is a non-linear, dynamic system. What that means is that if you have the perfect climate model (which, we don't) and you're off on your input of the parameters to that model by the slightest bit, the outcomes will veer off wildly from modeled expectations.

NeedMoreTea2• 7 years ago

Here's all the likely causes of warming - earth's orbit, sun, aerosols, volcanoes etc each overlaid on observed over the last 125 years as you scroll down. You decide.

https://www.bloomberg.com/graphics/2015-whats-warming-the-wo...

tzs• 7 years ago

We can directly measure that there has been a large increase in the amount of greenhouse gases in the atmosphere. It's extremely well established both experimentally and theoretically how the responses of greenhouse gases to different frequencies of electromagnetic radiation lead to warming. We can probably also actually measure the energy coming in from the Sun, and with satellites measure the amount going out, to further verify that the greenhouse gases are behaving as expected.

That allows us to reduce your question to how do we rule out that the increases in greenhouse gases are due to random variation?

For CO2, we can answer that by looking at different carbon isotopes. CO2 in living plants, CO2 in long dead plants, CO2 in volcanic gas emissions, and CO2 from weathering rock all have distinctly different ratios of carbon isotopes. By looking at the isotope distribution on the carbon in the atmosphere, we can show that most of the increase is from long dead plants--in other words, from burning coal and oil.

inspirel• 7 years ago

Climate change over time.

Analyticss• 7 years ago

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!

travisoneill1• 7 years ago

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/, which shows the same time period as basically a flat line. Who is right?

fhars• 7 years ago

Both, one is a single data point at a single location, the other is global trend. The medieval warm period wasn‘t warmer than the average on average either, it was just a local fluctuation.

guelo• 7 years ago

According to this[1] that graph is frequently used by climate skeptics but it is outdated and incorrect.

[1] https://www.carbonbrief.org/factcheck-what-greenland-ice-cor...

monort• 7 years ago

Chart in xkcd is for global and smoothed temperature (proxy measurements with 200 years resolution), so it downplays abrupt and regional temperature changes like in Greenland or Younger Dryas

https://earthscience.stackexchange.com/questions/9103/how-do...

ffellow• 7 years ago

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.

perl4ever6• 7 years ago

"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.

pts_• 7 years ago

Funny I just read this https://m.timesofindia.com/india/two-major-floods-wiped-out-...

SideburnsOfDoom4• 7 years ago

What is the likely cause of this event?

phkahler• 7 years ago

What will this be called in 100 years?

ithkuil• 7 years ago

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

g3orge• 7 years ago

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• 7 years ago

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

4.2 Kiloyear Event

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