1732: "Earth Temperature Timeline"

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codehead
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Re: 1732: "Earth Temperature Timeline"

Postby codehead » Tue Sep 13, 2016 7:07 am UTC

Two comments:

1. Past temperature trends are heavily averaged/estimated. That's alluded to in the "Limits of this data" section, but I have my doubts we can be so certain of the "unlikely"-type fluctuations over the chart's history. (For instance, 4500-3000 BCE is pretty much a flatline—what exactly is "small or brief enough" over a 1500 year period? Our "warming of concern" has been over a few decades. I think there is an assumption being made here that is greater than our actual knowledge. At minimum, it's misleading to the casual viewer to see nothing but historically smooth changes until modern times.)

2. There just hasn't been the large global average temperature change over the past 19 years that the chart shows. I suppose it's the product of the smoothing chosen, but, I don't see how. Also, the chart flatlines through the 19th century, and we know that didn't happen. We have temperature records through much of that century (particularly the second half, as indicated), so I'd expect the smoothing to be on the same order as recent years—but it doesn't appear to be.

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Re: 1732: "Earth Temperature Timeline"

Postby Steve the Pocket » Tue Sep 13, 2016 7:41 am UTC

To all the skeptics reading this thread: OK, so you still believe that global warming is just a random fluctuation that would have happened anyway and happens once or twice an eon anyway, and that this is just the first time we're seeing it happen in our species' lifetime. Fine. Let's suppose that's true. But the degree at which the planet is warming is still alarming and, if it continues, will almost inevitably lead to what for all intents and purposes we could call the apocalypse. The way I see it, if said apocalypse is inevitable, then getting used to relying less on fossil fuels and energy in general now can only make us better prepared to survive through it. There is no scenario where "continue to waste oil and coal like it grows on trees" is an appropriate response.
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Re: 1732: "Earth Temperature Timeline"

Postby wayne » Tue Sep 13, 2016 8:21 am UTC

Considering that the Earth has a slightly eccentric orbit and a variable axial tilt, what effect do these have on weather and climate?
The eccentricity and axial tilt both vary, both by precession and angle, and most of our land mass is in the northern hemisphere.
These factors all combine to make weather warmer when the northern hemisphere is in summer when we are at perihelion, but does water, with its higher heat capacity, make the overall climate warmer when the southern summer is at perihelion, even though the weather might be a bit cooler day-by-day?
And what is the period for these phases? I'm guessing that they are longer than the timescale of this comic.
Has anyone done a study on this?

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Re: 1732: "Earth Temperature Timeline"

Postby CharlieP » Tue Sep 13, 2016 8:39 am UTC

Steve the Pocket wrote:There is no scenario where "continue to waste oil and coal like it grows on trees" is an appropriate response.


ITYM no realistic scenario. If you're expecting the Rapture any day now you're probably not going to worry if the oil wells are going to run dry.
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Re: 1732: "Earth Temperature Timeline"

Postby Neil_Boekend » Tue Sep 13, 2016 8:50 am UTC

commodorejohn wrote:
HiFranc wrote:I can't remember where I heard it but I'm sure that archaeologists now have evidence that the Americas were populated before the land bridge (that is now the Bering Straits) formed.

I'd be really interested to hear more about this. Modern explorers have demonstrated that ships from ancient Egypt could have been used for trans-Atlantic crossings, but I've never heard of such a thing being seriously put forward as a possible historic event. (And anyway there's another 7-15 millennia separating that era and the period between the emergence of Beringia and the hypothesized migration to the Americas over it - but then again, I understand that Borneo, Australia, and New Zealand are supposed to have been colonized well before that, though those are considerably shorter distances.)

I'm curious if that required a design that doesn't have additional benifits over a design that could only be used in the Mediterranean.

cellocgw wrote:
Stargazer71 wrote:Hmmmm ... I suddenly want to create a graph of the Dow Jones for the last 50 years (adjusted for inflation, plotted on a sliding average of 5 years). Then 1 month from the end of the graph, I'll switch over to a daily graph. Just for fun.

The economy is on the fritz by the way. The graph I'm about to make will prove it.


Naah... the DJIA is a fractal curve. Aside from some very low-frequency shapes, it looks the same no matter how you zoom (semi-joke). If Randall had plotted on linear time, the curve at the end would have been brutally vertical.


Anyway, I actually came here to say "Yay, he remembered Asterix!"

Non-linear graphs are for quitters who can't find enough paper to make their point properly.
This is linear scale. In the last 500 years he just opted for markers every 100 years, spaced at 1/5th of the distance. As is proper.

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The natural world might benefit by us dying off somewhat, we do mess with nature all the time for our benefit. However I would point out that we are probably the only force on this planet that could ever hope to prevent, for instance, a cometary extinction event. Nature would certainly benefit from any efforts on our part to block that.

Don't anthropomorphize the nature. She doesn't like that.
Nature doesn't have a plan. Nature is just random chance and lots and lots of feedback loops. Such a rare event as a cometary extinction event is not something nature does anything about. That's not how it works.
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Re: 1732: "Earth Temperature Timeline"

Postby J L » Tue Sep 13, 2016 8:52 am UTC

Anyone who still argues "but the world climate has changed before" misses the point of the comic.

4° difference is enough to bury Boston under a mile of ice. Or to shape the face of continents.

So yes, some "changes" might be inevitable. But we couldn't live on a planet like this any more. No matter who or what's to blame for it -- we don't want that.

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Re: 1732: "Earth Temperature Timeline"

Postby RGB-es » Tue Sep 13, 2016 9:54 am UTC

wayne wrote:Considering that the Earth has a slightly eccentric orbit and a variable axial tilt, what effect do these have on weather and climate?
The eccentricity and axial tilt both vary, both by precession and angle, and most of our land mass is in the northern hemisphere.
These factors all combine to make weather warmer when the northern hemisphere is in summer when we are at perihelion, but does water, with its higher heat capacity, make the overall climate warmer when the southern summer is at perihelion, even though the weather might be a bit cooler day-by-day?
And what is the period for these phases? I'm guessing that they are longer than the timescale of this comic.
Has anyone done a study on this?


Those are the Milankovitch cycles. The guys at the PBS Space Time Channel have a really nice video about them.

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Re: 1732: "Earth Temperature Timeline"

Postby KarenRei » Tue Sep 13, 2016 9:56 am UTC

So, apparently Elon Musk is an XKCD fan ;)

https://twitter.com/elonmusk/status/775632728548970500

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Re: 1732: "Earth Temperature Timeline"

Postby Flumble » Tue Sep 13, 2016 10:59 am UTC

Pyrite wrote:On a side note, did it really take us 500 years to go from working copper to working gold?

I mean, gold nuggets show up in riverbeds and you can melt the stuff in a campfire. What took them so long?

There are error bars of (at least) 1000 years on both according to wikipedia. It's plausible some tribes started smelting gold before copper, tin and lead.

Also both copper and gold have melting temperatures of 1000-1100°C, so don't you need a charcoal fire for either material to do metallurgy?

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Re: 1732: "Earth Temperature Timeline"

Postby Bledlow » Tue Sep 13, 2016 11:19 am UTC

jozwa wrote:History is so cool. No pun intended.

Also, is "Atilla" a typo or an alternative spelling?

A mistake, I think, not a typo. Like 'Ghengis', which should be 'Genghis'. It's Italian spelling. The 'h' is there so that the 'g' before an 'i' or 'e' is pronounced 'g' as in got, not 'j' as in jam. I think it's Chingis (hard 'g') in proper Mongolian.

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Re: 1732: "Earth Temperature Timeline"

Postby SecondTalon » Tue Sep 13, 2016 11:22 am UTC

Stargazer71 wrote:meaniehead as a pejorative about a dozen times


Here's what's going to happen.

It's unavoidable that I'm going to tell you to knock off the meaniehead insult stream. It's not applicable to the sort of person you're wanting to argue about because SWJs aren't made of straw. It's also just nonspecifically insulting in a general "If you don't agree with me you're an idiot sheeple" sort of way.

What is avoidable is everything that happens next.

In option A, we have a lengthy conversation where I reiterate the rules and the philosophy of the forum and you understand that even based insults generally don't do so well here, especially outside of particular groups and associations as they lack context and all that and agree to knock it off, actually knock it off, and everyone moves on with no harm done.

Based on my experience, I give that option 50:1 odds.

The other option is option B, where you argue back, likely about free speech and your rights (forgetting the xkcd forum is not a US Government institution. Or even a public space) and possibly even continue insulting people, perhaps myself included (as clearly I am a SWJ since I'm defending them), maybe publicly, maybe in private messages. Perhaps another mod also tries to make the same points in other language but they don't get through and the end result is that in a couple of days or a week, we ban you for being a disruption.

Again, based on experience of how this goes down, I figure that's the rest of it - 50:49 odds.

Now, I'm on a phone and it'll be hours and hours before I can get on a computer, so I'm really not interested in either option, but especially not the likely argument chain of option B. So just tell me which one you want and I'll make it happen.

If you can't get the hint, this is me saying I'm about to ban you for anything that isn't a "My bad, won't happen again" because, like I said, I've seen this all before and know how it generally goes down and I just can't do it today, so I want to completely skip all the in between stuff



MikeDamrat wrote:
When did "meaniehead" come to apply to something other than people who argue about topics related to social science/social justice? [...]
Does it now just mean "people on the internet who annoy me"?

Right about when "gay" and "fag" became socially unacceptable insults online.
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Re: 1732: "Earth Temperature Timeline"

Postby Bledlow » Tue Sep 13, 2016 11:35 am UTC

commodorejohn wrote:
HiFranc wrote:I can't remember where I heard it but I'm sure that archaeologists now have evidence that the Americas were populated before the land bridge (that is now the Bering Straits) formed.

I'd be really interested to hear more about this. Modern explorers have demonstrated that ships from ancient Egypt could have been used for trans-Atlantic crossings, but I've never heard of such a thing being seriously put forward as a possible historic event. (And anyway there's another 7-15 millennia separating that era and the period between the emergence of Beringia and the hypothesized migration to the Americas over it - but then again, I understand that Borneo, Australia, and New Zealand are supposed to have been colonized well before that, though those are considerably shorter distances.)

Not New Zealand.

As far as we can tell, that was settled in what in Europe we call the Middle Ages. The Maori language is obviously East Polynesian, & Maori speakers report that they can converse with speakers of some East Polynesian dialects, e.g. from the Cook Islands, which is consistent with a split within hundreds rather than thousands of years. There are also clear cultural, genetic & material connections, & the Maori legends recorded by early European visitors, all consistent with that date.

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Re: 1732: "Earth Temperature Timeline"

Postby KarenRei » Tue Sep 13, 2016 11:36 am UTC

SecondTalon wrote:
Stargazer71 wrote:meaniehead as a pejorative about a dozen times


Here's what's going to happen.... ... (snip)


Where's a "Like" button when you need one?

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Re: 1732: "Earth Temperature Timeline"

Postby gmalivuk » Tue Sep 13, 2016 11:47 am UTC

Like all mods, I believe ST accepts "likes" in the form of booze.

codehead wrote:2. There just hasn't been the large global average temperature change over the past 19 years that the chart shows.

This was disingenuous back when denialists were saying 17 years but now it's just getting absurd.
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Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Tue Sep 13, 2016 11:58 am UTC

mschmidt62 wrote:[...]the Younger Dryas [...]

Are they a hip-hop ensemble of some renown, m'lud?

[reference]
Last edited by orthogon on Tue Sep 13, 2016 12:00 pm UTC, edited 1 time in total.
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Re: 1732: "Earth Temperature Timeline"

Postby SecondTalon » Tue Sep 13, 2016 12:00 pm UTC

gmalivuk wrote:Like all mods, I believe ST accepts "likes" in the form of booze.

Unlike most mods, I prefer beer.

Unless you can get Ol' Pappy.
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Re: 1732: "Earth Temperature Timeline"

Postby thoughtdreams » Tue Sep 13, 2016 12:39 pm UTC

oh well, all good things come to an end. sad but forseeable for a while now.

too bad xkcd isnt printed on old-timey newsprint for easier burning during the coming ice age (sure, it could be printed out on printer paper but that seems an unneccessary step)

if history teaches us one thing, it is that when the 'ptb' reach a consensus, it is always, always, always 180 degrees in the wrong direction.

another way of saying it: if you get your science knowledge from politicians, bureaucrats, and their media, you will be forever misguided (but still useful to the ptb).

cruder version: if you think politicans know more about math and science than you do, you might be right!

so, in addition to all the actual science debunking the AGW hoax, we have an unofficial but highly accurate contrarian indicator. act accordingly!

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Re: 1732: "Earth Temperature Timeline"

Postby melthengylf » Tue Sep 13, 2016 12:40 pm UTC

We all know, that the correct way to put the problem of time scales forward is to smooth present temperature change in the same way older t change was done and understand the effect then.

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Re: 1732: "Earth Temperature Timeline"

Postby Angua » Tue Sep 13, 2016 12:43 pm UTC

gmalivuk wrote:Like all mods, I believe ST accepts "likes" in the form of booze.

codehead wrote:2. There just hasn't been the large global average temperature change over the past 19 years that the chart shows.

This was disingenuous back when denialists were saying 17 years but now it's just getting absurd.

#notallmods.

Though I will accept chocolate liqueurs if it must be booze based
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Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Tue Sep 13, 2016 12:50 pm UTC

Ooh, is that a Spinal Tap reference circa 2200BCE? Respect.
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1732: "Earth Temperature Timeline"

Postby JudeMorrigan » Tue Sep 13, 2016 1:08 pm UTC

thoughtdreams wrote:another way of saying it: if you get your science knowledge from politicians, bureaucrats, and their media, you will be forever misguided (but still useful to the ptb).

Physician, heal thyself.

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Re: 1732: "Earth Temperature Timeline"

Postby PeteP » Tue Sep 13, 2016 1:31 pm UTC

Ptb? The Physikalisch-Technische Bundesanstalt? For others who have no idea what ptb is, it means "powers that be" :roll: .

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Re: 1732: "Earth Temperature Timeline"

Postby Jeff_UK » Tue Sep 13, 2016 1:35 pm UTC

As I am being faintly critical of something relating to climate change, I feel I have to preface this with "I am not a climate change denying nutcase" However, I am a pedant, and a nit-picker..

We all know, that the correct way to put the problem of time scales forward is to smooth present temperature change in the same way older t change was done and understand the effect then.


Actually, an indication of the scale on the graphs in the 'limits of this data' section would go a long way to understanding how 'special' the current spike is likely to be (i.e. 'always label your damn axes Randall' http://xkcd.com/833/)
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Re: 1732: "Earth Temperature Timeline"

Postby SDK » Tue Sep 13, 2016 1:46 pm UTC

Jeff_UK wrote:Actually, an indication of the scale on the graphs in the 'limits of this data' section would go a long way to understanding how 'special' the current spike is likely to be (i.e. 'always label your damn axes Randall')

Though it's not explicitly spelled out, the fact that the frequency of data points in his examples mirror exactly with the data points along the graph itself, I think it's safe to assume it's on the same scale.


I haven't been around all that long, and I've always thought it strange that the folks in the Science section tend to disregard people for not using capitalization, but you'll be happy to know that today is the day I started agreeing with that philosophy.
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Re: 1732: "Earth Temperature Timeline"

Postby Felagund » Tue Sep 13, 2016 2:20 pm UTC

The cursory explanation that the Medieval Warm Period was not global in scope is really disappointing from a site that usually prides itself on all matters technical. There are many different temperature proxies from all over the world (New Zealand, Africa, South America, etc. etc.) that show that time period to be warmer than today. At least one major study from Science in 2013 showed that there was indeed a global MWP. Even more or less alarmist groups like IPCC don't go so far as to say the MWP didn't exist, but that the scope is uncertain. When you say it didn't exist you are basically just quoting one study from Michael Mann, who is very self-interested, and running with it.

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Re: 1732: "Earth Temperature Timeline"

Postby operagost » Tue Sep 13, 2016 2:22 pm UTC

Amaroq wrote:Surely Randall didn't cherry pick data on purpose, did he?

Image

Well, he certainly cherry-picked the start of the timeline.

Starting 100,000 years ago would have made today's temperatures look cold, but then we believe that humans didn't exist yet so...

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Re: 1732: "Earth Temperature Timeline"

Postby bob443@mahaska.org » Tue Sep 13, 2016 2:27 pm UTC

Well, the actual hockey stick graph shows the sudden onset of warming about 1900, by sudden I mean a quarter of a degree celsius in 50 years, followed by a short hiatus of maybe 10 years, right around WWII, followed by another quarter degree in the following 25 year time frame. This graph shows about 0.1 degree warming in that timeframe, ostensibly 'saving' some of that warming for the latter half of the 20th century. If Mann's hockey stick graph had presented this data in 1997, MBH would have been a complete yawner and nobody would have paid them to continue collecting bristle-cones on the Yamal peninsula. Data since the end of the late 20th century uptick has been pretty flat. 1998 was an anomalous El-Nino period, followed by about 18 years of gradually declining temps, followed by 2016, another strong El-Nino event. If you toss out the two El-Nino's, the graph goes flat in the year 2000 and remains so to this day, when considering that the global temp has declined suddenly in the last 4 months following the end of the 2016 El-Nino and is somewhere around the average for the last decade, at this time.

They are obviously using Gavin's "adjusted" temperature set, the same one Brian Cox used, rather than the rss-land satelite (UAB) based temp set, which shows essentially no warming since 2000, except for the strong uptick associated with the aforementioned El-Nino, which has now ended.

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Re: 1732: "Earth Temperature Timeline"

Postby Tobias » Tue Sep 13, 2016 2:30 pm UTC

Jeff_UK wrote:Actually, an indication of the scale on the graphs in the 'limits of this data' section would go a long way to understanding how 'special' the current spike is likely to be (i.e. 'always label your damn axes Randall' http://xkcd.com/833/)

What... what are you talking about? The axes are labelled. The scale does not change. It very obviously does not change, and we can see that, because it is labeled!

What exactly are you asking for that the graph doesn't provide here?

QuakeIV wrote:The earth is just a bunch of metal with a thin layer of glorified space dust on top. I don't think it really cares about the machinations of that dust at this point in time.

The natural world might benefit by us dying off somewhat


Remember always that humans are not ghosts or wizards, we are part of nature. The longer warming trends indicate warming has happened before,and this time is no less natural than those were, the only difference now is us, and it is we that have a vested interested in smoothing out Earth's temperature.

Is the warming human caused? It doesn't matter. (It is, but it doesn't matter) We need to do what we can to stop it, because regardless of the cause it is bad for us, and even if we weren't responsible (which we are), it would be absolutely vital that we develop a way to stop it (and we should be glad we are responsible, since it makes the way to stop it a lot easier than it otherwise would be).

That's the part I don't get - the people who argue it's not human caused and so we should do... nothing!? That just makes the problem harder! If you want a minimal amount of government interference and spending and social upheaval and business disruption or what-the-fuck-ever, human-caused climate change is exactly what you should be praying for, because the alternative where we are going to have to fight global forces that are 100% out of our control is not going to be an easier problem to tackle! And if your argument is that we shouldn't try and should just give up, why don't you do the same right now and get out of our way.


operagost wrote:Starting 100,000 years ago would have made today's temperatures look cold, but then we believe that humans didn't exist yet so...

Actually it wouldn't have? And even if we started at the hottest point, which was before then, it wasn't much hotter than today, and most of that time period is actually significantly colder. (Look at the heritage graft getting down to three times lower in temp than Randall's graph!) It actually would have made today's warming seem even worse, not better.

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Re: 1732: "Earth Temperature Timeline"

Postby PeteP » Tue Sep 13, 2016 2:44 pm UTC

bob443@mahaska.org wrote:Well, the actual hockey stick graph shows the sudden onset of warming about 1900, by sudden I mean a quarter of a degree celsius in 50 years, followed by a short hiatus of maybe 10 years, right around WWII, followed by another quarter degree in the following 25 year time frame. This graph shows about 0.1 degree warming in that timeframe, ostensibly 'saving' some of that warming for the latter half of the 20th century. If Mann's hockey stick graph had presented this data in 1997, MBH would have been a complete yawner and nobody would have paid them to continue collecting bristle-cones on the Yamal peninsula. Data since the end of the late 20th century uptick has been pretty flat. 1998 was an anomalous El-Nino period, followed by about 18 years of gradually declining temps, followed by 2016, another strong El-Nino event. If you toss out the two El-Nino's, the graph goes flat in the year 2000 and remains so to this day, when considering that the global temp has declined suddenly in the last 4 months following the end of the 2016 El-Nino and is somewhere around the average for the last decade, at this time.

They are obviously using Gavin's "adjusted" temperature set, the same one Brian Cox used, rather than the rss-land satelite (UAB) based temp set, which shows essentially no warming since 2000, except for the strong uptick associated with the aforementioned El-Nino, which has now ended.

Do some basic googling about the claim that the temp stopped changed, then if you have anything convincing to say against the points saying that that isn't correct it might be more interesting.

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Re: 1732: "Earth Temperature Timeline"

Postby Mutex » Tue Sep 13, 2016 2:58 pm UTC

operagost wrote:Well, he certainly cherry-picked the start of the timeline.

Starting 100,000 years ago would have made today's temperatures look cold, but then we believe that humans didn't exist yet so...


You misunderstood the point of the graph. The point isn't about whether or not the climate was ever hotter in the past. The point is that temperature changes in the past took place over thousands of years, not decades. Randell could have started the graph at a time when the climate was hotter than now, it wouldn't have invalidated his point, it would just make the graph bigger.

That graph Amaroq posted has the problem that it's showing a very large amount of time, compressed into a small space. So changes over thousands of years, and changes over decades, look the same. If the warming we've seen in the last 50 years took place over 5000 years there'd be little or no problem.

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Re: 1732: "Earth Temperature Timeline"

Postby thoughtdreams » Tue Sep 13, 2016 3:04 pm UTC

The right-hand side of the bell curve should just go full Golgafrinchan - load up all the politicos, meanieheads, bureaucrats, NGOs, media and academic lapdogs, even the concern trolls. Oh, and throw in telephone spammers, just because.

It would be like pre-1998 internet, before the Great Dumbing Down.
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Re: 1732: "Earth Temperature Timeline"

Postby somitomi » Tue Sep 13, 2016 3:47 pm UTC

Tobias wrote:Is the warming human caused? It doesn't matter. (It is, but it doesn't matter) We need to do what we can to stop it, because regardless of the cause it is bad for us, and even if we weren't responsible (which we are), it would be absolutely vital that we develop a way to stop it (and we should be glad we are responsible, since it makes the way to stop it a lot easier than it otherwise would be).

That's the part I don't get - the people who argue it's not human caused and so we should do... nothing!? That just makes the problem harder! If you want a minimal amount of government interference and spending and social upheaval and business disruption or what-the-fuck-ever, human-caused climate change is exactly what you should be praying for, because the alternative where we are going to have to fight global forces that are 100% out of our control is not going to be an easier problem to tackle! And if your argument is that we shouldn't try and should just give up, why don't you do the same right now and get out of our way.

GOTO:
Where's a "Like" button when you need one?


CharlieP wrote:ITYM no realistic scenario. If you're expecting the Rapture any day now you're probably not going to worry if the oil wells are going to run dry.

OFF:
I think you mean "I think you mean no realistic scenario."
Sorry, but these abbreviations bug me, because I have to look up the meaning of roughly nine out of ten. In my opinion, that completely defeats the purpose of written language for the sake of saving a few keystrokes on your part, essentially transfering them to folks like me.
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Re: 1732: "Earth Temperature Timeline"

Postby HES » Tue Sep 13, 2016 3:54 pm UTC

Tobias wrote:What... what are you talking about? The axes are labelled.

On the main graph, sure, but some of the little inset explanatory graphs do have unlabelled axes.
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Re: 1732: "Earth Temperature Timeline"

Postby thunk » Tue Sep 13, 2016 3:56 pm UTC

The deniers always focus on the short-to-medium term temperatures, while ignoring the long-run trend. Gee, I wonder why? Because you can always draw trendlines through short-term data that point any way you want.

Image

In any case, the last *30* years demonstrate that the Earth has been warming--whether it be the GISTEMP you claim has been "faked", the BEST data set made by former skeptics, or the UAH6.0 deniers have been crowing about recently. 1

I even threw out the post-2015 El Nino bump just to be nice, though it doesn't make much difference at this timescale.

1As usual, the linked graphs conveniently start out before the 1998 El Nino.
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Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Tue Sep 13, 2016 4:14 pm UTC

Felagund wrote:The cursory explanation that the Medieval Warm Period was not global in scope is really disappointing from a site that usually prides itself on all matters technical. There are many different temperature proxies from all over the world (New Zealand, Africa, South America, etc. etc.) that show that time period to be warmer than today. At least one major study from Science in 2013 showed that there was indeed a global MWP. Even more or less alarmist groups like IPCC don't go so far as to say the MWP didn't exist, but that the scope is uncertain. When you say it didn't exist you are basically just quoting one study from Michael Mann, who is very self-interested, and running with it.


Maybe the Medieval Warm Period wasn't global in scope just because the Middle Ages weren't global in scope :wink:
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1732: "Earth Temperature Timeline"

Postby Jeff_UK » Tue Sep 13, 2016 4:28 pm UTC

Tobias wrote:
Jeff_UK wrote:Actually, an indication of the scale on the graphs in the 'limits of this data' section would go a long way to understanding how 'special' the current spike is likely to be (i.e. 'always label your damn axes Randall' http://xkcd.com/833/)

What... what are you talking about? The axes are labelled. The scale does not change. It very obviously does not change, and we can see that, because it is labeled!

What exactly are you asking for that the graph doesn't provide here?


Exactly what I said.!

there is a section titled 'Limits of this Data', it contains graphs, their axes are not labelled..

It would be interesting to know how short or brief a spike would have to be to be 'smoothed out' in the historical data.
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Re: 1732: "Earth Temperature Timeline"

Postby cdfrick » Tue Sep 13, 2016 4:30 pm UTC

Steve the Pocket wrote:To all the skeptics reading this thread: OK, so you still believe that global warming is just a random fluctuation that would have happened anyway and happens once or twice an eon anyway, and that this is just the first time we're seeing it happen in our species' lifetime. Fine. Let's suppose that's true. But the degree at which the planet is warming is still alarming and, if it continues, will almost inevitably lead to what for all intents and purposes we could call the apocalypse. The way I see it, if said apocalypse is inevitable, then getting used to relying less on fossil fuels and energy in general now can only make us better prepared to survive through it. There is no scenario where "continue to waste oil and coal like it grows on trees" is an appropriate response.


The interesting thing about "anthropogenic climate forcing" (as it was called in the early '00s), if such a thing exists, is that so far efforts to limit emissions have apparently made things worse rather than better. In the smog-filled '70s, "global cooling" was all the rage, yet industrial emissions were far worse than today - but all that airborne pollution acted as a self-controlling mechanism to keep temperatures from rising. (And no, I'm not advocating for pumping the air full of pollutants again, for the record, but increases in airborne particulates have a strong inverse correlation to temperature.) Now that coal-powered energy plants and gas-powered vehicles are running cleaner, why is the problem getting worse?

I would argue that your "apocalypse" scenario has much less to do with fossil fuels, and more to do with city-building along the coasts, in particular the east coast of the United States. The effect of replacing an enormous amount of light- and heat-absorbing grass and earth with an equally enormous amount of light- and heat-reflecting asphalt and concrete adjacent to a large, sensitive body of water is something that deserves a bit more discussion in the whole "humans are destroying the environment" debate. The disruption to the North Atlantic Oscillation does far more to explain the recent temperature trends, but it's easier to push the blame on "big oil" than to ask tens of millions of people to relocate...even if it doesn't fix a big part of the problem.

The industrial era began before automobiles (and roads, and parking lots) were invented. Early industry was dirty, and there's no denying that pollution was a problem (airborne or otherwise). While industry advanced, humans discovered oil, created cars, and built megalopolises, all under cover of dust and smoke. And when the smoke finally cleared, the sun shone down on an altered landscape, not soft and green but hard and grey...and all the heat that wasn't being absorbed had to go somewhere else.

Just an alternative to consider.

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Re: 1732: "Earth Temperature Timeline"

Postby cdfrick » Tue Sep 13, 2016 4:32 pm UTC

wayne wrote:Considering that the Earth has a slightly eccentric orbit and a variable axial tilt, what effect do these have on weather and climate?
The eccentricity and axial tilt both vary, both by precession and angle, and most of our land mass is in the northern hemisphere.
These factors all combine to make weather warmer when the northern hemisphere is in summer when we are at perihelion, but does water, with its higher heat capacity, make the overall climate warmer when the southern summer is at perihelion, even though the weather might be a bit cooler day-by-day?
And what is the period for these phases? I'm guessing that they are longer than the timescale of this comic.
Has anyone done a study on this?


Yes, although it's been 11 years and I don't have access to my original data (pre-internet) to cite sources, so feel free to take this with a grain of salt or investigate further.

I was able to identify four (4) periodic cycles:

Earth's orbital precession, which operates on a ~23-Kyr cycle
Earth's obliquity (axial tilt), which operates on a ~41-Kyr cycle
Earth's eccentricity, which appears to operate on two cycles, one at ~100-Kyr and an apparent larger trend at ~400-Kyr

The short version of the answer to your question is that yes, the period of those phases is longer than the timescale of this comic.

For what it's worth, using primarily geologic (Oxygen-18) and Antarctic ice-core indicators to determine historical temperature fluctuations, I wasn't able to find a significant correlation between Earth's orbital movements and global temperature on a millennial scale. The eccentricity graph looks neat, but the peaks are offset from temperature spikes by several thousand years (for instance, the three most recent temperature peaks occurred at ~125 Kyr, 240 Kyr, and 325 Kyr before present, while the maximum eccentricity peaks occurred at ~110 Kyr [0.04 eccentricity], 210 Kyr [0.05], and 305 Kyr [0.04] before present).

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Re: 1732: "Earth Temperature Timeline"

Postby Mutex » Tue Sep 13, 2016 4:34 pm UTC

Jeff_UK wrote:
Tobias wrote:
Jeff_UK wrote:Actually, an indication of the scale on the graphs in the 'limits of this data' section would go a long way to understanding how 'special' the current spike is likely to be (i.e. 'always label your damn axes Randall' http://xkcd.com/833/)

What... what are you talking about? The axes are labelled. The scale does not change. It very obviously does not change, and we can see that, because it is labeled!

What exactly are you asking for that the graph doesn't provide here?


Exactly what I said.!

there is a section titled 'Limits of this Data', it contains graphs, their axes are not labelled..

It would be interesting to know how short or brief a spike would have to be to be 'smoothed out' in the historical data.


I assume they're to the same scale as the rest of the graph. So the "unlikely" spike is about a century from start to finish (50 years to reach the peak, another 50 years to revert to the norm). So if the last 50 years of warming we've was the first half of a spike, we should be able to see previous spikes the same size in the historical data.

Edit to add:

cdfrick wrote:The interesting thing about "anthropogenic climate forcing" (as it was called in the early '00s), if such a thing exists, is that so far efforts to limit emissions have apparently made things worse rather than better. In the smog-filled '70s, "global cooling" was all the rage,


It was only all the rage in the mainstream media. The majority of scientists at that time were far more concerned with the possibility we were warming up the planet, and it took decades for anyone to listen to them.

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Re: 1732: "Earth Temperature Timeline"

Postby Felagund » Tue Sep 13, 2016 4:48 pm UTC

See this link for studies demonstrating the global nature of the Medieval Warm Period. http://kaltesonne.de/mapping-the-medieval-warm-period/


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